From hbr@mailman.qth.net  Tue Apr  1 21:55:33 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 1 Apr 2003 15:55:33 -0600
Subject: [HBR] Fw: Re: HBR-14
Message-ID: <20030401.155537.-242781.12.windy10605@juno.com>

Yes, I would appreciate it if you would place a note on the reflector
site
re my wanting a HBR-14..
73's
Clint, K4krb

--------- Forwarded message ----------
From: "C.Gorman" <cgorman@bellsouth.net>
To: <k5bcq@arrl.net>
Date: Tue, 1 Apr 2003 14:37:39 -0800
Subject: HBR-14
Message-ID: <001e01c2f89f$4dde54a0$9738d6d1@oemcomputer>

Kees..... I built a HBR-14 back  in 1957, used it a long time and sold
it.
Now I am wanting one again, but I know parts would be very hard to
find.....(I don't have that many years to go....Hi).
Would like to know if there is one available that you know of. I would
like
to purchase one regardless of completeness.
73's,
Clint, k4krb

From hbr@mailman.qth.net  Wed Apr  2 21:22:44 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Wed, 2 Apr 2003 15:22:44 -0600
Subject: [HBR] Fw: HBR 16 Receiver
Message-ID: <20030402.152248.-356963.3.windy10605@juno.com>

Hi John,

I just added you to the HBR reflector. There are better versions of the
schematics 
on the HBR CD since I was not restricted to space with the CD. If you
want one
they are $10 postpaid from me. I'll have to call up the schematics on the
web site
and review the legibility. The schematics on the web site are in .jpg
format and
those on the CD are in .pdf format.

73  Kees K5BCQ


--------- Forwarded message ----------
From: jparker@onemain.com
To: k5bcq@arrl.net
Date: Wed, 2 Apr 2003 13:06:47 -0800 (PST)
Subject: HBR 16 Receiver
Message-ID:
<3150284.1049317607939.JavaMail.nobody@ernie.psp.pas.earthlink.net>

Hello,

My name is John Parker, KD7KFT.  I have been looking for a nice homebuilt
receiver project and came across your web site.  

This sounds like a very exciting project.  For now, I have one question,
as I'm sure more questions will follow.

When I click on the schematic for the HBR-16 receiver and then print it
out, it doesn't come out very clear.  Any recommendations on how to deal
with this, so that I can read the schematic?


Tks,

John

From hbr@mailman.qth.net  Wed Apr  2 23:12:25 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Wed, 2 Apr 2003 15:12:25 -0800 (PST)
Subject: [HBR] Fw: HBR 16 Receiver
Message-ID: <4149808.1049325146117.JavaMail.nobody@thecount.psp.pas.earthlink.net>

Thank you for the quick reply.  In what way would you like the $10.00?

In these days of computers, etc.  There are many different ways;
i.e. Check, Money Order, Visa, PayPal, etc.

What works for you?

Tks,

John
-------Original Message-------
From: windy10605@juno.com
Sent: 04/02/03 01:22 PM
To: jparker@onemain.com
Subject: [HBR] Fw: HBR 16 Receiver

> 
> Hi John,

I just added you to the HBR reflector. There are better versions of the
schematics 
on the HBR CD since I was not restricted to space with the CD. If you
want one
they are $10 postpaid from me. I'll have to call up the schematics on the
web site
and review the legibility. The schematics on the web site are in .jpg
format and
those on the CD are in .pdf format.

73  Kees K5BCQ


--------- Forwarded message ----------
From: jparker@onemain.com
To: k5bcq@arrl.net
Date: Wed, 2 Apr 2003 13:06:47 -0800 (PST)
Subject: HBR 16 Receiver
Message-ID:
<3150284.1049317607939.JavaMail.nobody@ernie.psp.pas.earthlink.net>

Hello,

My name is John Parker, KD7KFT.  I have been looking for a nice homebuilt
receiver project and came across your web site.  

This sounds like a very exciting project.  For now, I have one question,
as I'm sure more questions will follow.

When I click on the schematic for the HBR-16 receiver and then print it
out, it doesn't come out very clear.  Any recommendations on how to deal
with this, so that I can read the schematic?


Tks,

John
************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
construction notes...... via <a target=_blank
href="http://www.qsl.net/k5bcq/">http://www.qsl.net/k5bcq/</a> 

Retrieve reflector archived data via <a target=_blank
href="http://mailman.qth.net/mailman/listinfo/hbr">http://mailman.qth.net/mailman/listinfo/hbr</a>

> 

From hbr@mailman.qth.net  Wed Apr  2 23:30:45 2003
From: hbr@mailman.qth.net (Jeff Noel)
Date: Wed, 2 Apr 2003 18:30:45 -0500
Subject: [HBR] Fw: HBR 16 Receiver
References: <20030402.152248.-356963.3.windy10605@juno.com>
Message-ID: <000c01c2f96f$f7faf3a0$6c302c42@hppav>

John,

Welcome to the HBR site. Kees does a fine job. I build a "16 a year ago
and I am amazed at its performance.

Jeff
K4ZKU


From hbr@mailman.qth.net  Thu Apr  3 00:12:00 2003
From: hbr@mailman.qth.net (Mike Feher)
Date: Wed, 02 Apr 2003 19:12:00 -0500
Subject: [HBR] Fw: HBR 16 Receiver
References: <20030402.152248.-356963.3.windy10605@juno.com>
 <000c01c2f96f$f7faf3a0$6c302c42@hppav>
Message-ID: <01c601c2f975$a7bb6040$0500a8c0@eoz>

Jeff -

Just think what it was like to have one as a kid in his late teens when I
built mine. Simply amazing. Regards to Marie. 73 - Mike



Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193



----- Original Message -----
From: "Jeff Noel" <k4zku@erols.com>
To: <hbr@mailman.qth.net>
Sent: Wednesday, April 02, 2003 6:30 PM
Subject: Re: [HBR] Fw: HBR 16 Receiver


> John,
>
> Welcome to the HBR site. Kees does a fine job. I build a "16 a year ago
> and I am amazed at its performance.
>
> Jeff
> K4ZKU
>
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
>
> Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr
>
>


From hbr@mailman.qth.net  Thu Apr  3 00:13:39 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Wed, 2 Apr 2003 16:13:39 -0800 (PST)
Subject: [HBR] Fw: HBR 16 Receiver
Message-ID: <7818486.1049328820354.JavaMail.root@statler.psp.pas.earthlink.net>

Hi Jeff,

Thanks for the Welcome aboard!!  I look forward to this project.  How long did it take you to gather everything and then how long assemble?  

Did you wait till you had all the parts, or did you build it as you went along?

I have put Heathkit kits together, but nothing like this.

It may prove to be a real challenge!!

Tks,

John
-------Original Message-------
From: Jeff Noel <k4zku@erols.com>
Sent: 04/02/03 03:30 PM
To: hbr@mailman.qth.net
Subject: Re: [HBR] Fw: HBR 16 Receiver

> 
> John,

Welcome to the HBR site. Kees does a fine job. I build a "16 a year ago
and I am amazed at its performance.

Jeff
K4ZKU

************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
construction notes...... via <a target=_blank
href="http://www.qsl.net/k5bcq/">http://www.qsl.net/k5bcq/</a> 

Retrieve reflector archived data via <a target=_blank
href="http://mailman.qth.net/mailman/listinfo/hbr">http://mailman.qth.net/mailman/listinfo/hbr</a>

> 

From hbr@mailman.qth.net  Thu Apr  3 00:42:03 2003
From: hbr@mailman.qth.net (Jeff Noel)
Date: Wed, 2 Apr 2003 19:42:03 -0500
Subject: [HBR] Fw: HBR 16 Receiver
References: <7818486.1049328820354.JavaMail.root@statler.psp.pas.earthlink.net>
Message-ID: <001c01c2f979$ef4300e0$6c302c42@hppav>

John,

The actual building time was a couple of months.
I had  a large junke box and had most of the hard parts to
get, dial,  IF trans from ARC 5s and had the power xfomer. Bought the
resistors, the old ones have changed value. The chassis and coil forms are
home brew. Check it out on Kees's web.

Hi  Mike.  I did not have the $$$  to build the HBR when I was a kid, but to
have a HBR then was a real treat.

Jeff



From hbr@mailman.qth.net  Thu Apr  3 05:03:48 2003
From: hbr@mailman.qth.net (Mike Feher)
Date: Thu, 03 Apr 2003 00:03:48 -0500
Subject: [HBR] Fw: HBR 16 Receiver
References: <7818486.1049328820354.JavaMail.root@statler.psp.pas.earthlink.net>
 <001c01c2f979$ef4300e0$6c302c42@hppav>
Message-ID: <026101c2f99e$698b21b0$0500a8c0@eoz>

Jeff -

I agree, I did not have the money either. I had a paper route and then
worked at a radio TV repair store. I was also a good baby sitter for my
teachers, HI. So, I was able to buy some parts, some were donated by other
hams, but, most of the critical items like the IFs came from ARC-5s that I
took apart. Shame on me. No Eddystone dial, but the Millen worked just fine.
Using the shop at high school for the mechanical stuff made it easier. All
the teachers were my friends since I fixed their TVs. Boy, today, to even
have a machine shop in HS would be a liability no one could afford.
Amazingly, back then, I do not recall anyone getting injured. But, back then
we did not expect the Government to save us from our own stupidity, HI. 73 -
Mike



Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193



----- Original Message -----
From: "Jeff Noel" <k4zku@erols.com>
To: <hbr@mailman.qth.net>
Sent: Wednesday, April 02, 2003 7:42 PM
Subject: Re: Re: [HBR] Fw: HBR 16 Receiver


> John,
>
> The actual building time was a couple of months.
> I had  a large junke box and had most of the hard parts to
> get, dial,  IF trans from ARC 5s and had the power xfomer. Bought the
> resistors, the old ones have changed value. The chassis and coil forms are
> home brew. Check it out on Kees's web.
>
> Hi  Mike.  I did not have the $$$  to build the HBR when I was a kid, but
to
> have a HBR then was a real treat.
>
> Jeff
>
>
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
>
> Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr
>
>


From hbr@mailman.qth.net  Sun Apr  6 17:01:12 2003
From: hbr@mailman.qth.net (Eddy Swynar)
Date: Sun, 6 Apr 2003 12:01:12 -0400
Subject: [HBR] Homebrewed Receiver Available...
Message-ID: <001601c2fc55$e6e6cba0$d6d549c6@greg>

Greetings All,

If you've ever longed to find a homebrewed receiver of your own at different
swap meets but were unsuccessful, here's a chance to bring out the best
"...tinkerer & experimenter" within you...

Not long ago, I purchased a home made 13-tube rig passed down to an
out-of-town fellow Amateur. The receiver intrigued me because---YES!!!---the
original builder incorporated that famous EDDYSTONE slide rule dial. It
works on 40-meters well enough (I just listened to a bunch of AM'ers up in
the north-east on 7290), but the other bands are dead...obviously needs some
TLC to get them going. But the radio apparently is capable of tuning all of
the traditional bands (judging by the markings on the dial & bandswitch),
INCLUDING 160-meters...

The beast weighs 30 pounds, & was built behind a standard 19" rack
front---the depth of it is 14". The knobs---with the exception of the main
tuning---are AR-88/RCA-style in appearance.

The receiver appears to have been British-inspired: I thought it may have
been the "G2DAF Communication Receiver", which was featured in the RSGB
BULLETIN of July-November 1960, & March-April 1961, but the builder
apparently utilized L/C networks (as opposed to crystals) in the local
oscillators/BFOs.

I don't think this is any sort of an HBR, because of the obvious English
references on some of the parts, per my photos.

I'd like to sell this radio without the hassles of eBay. It's a good
foundation for a quality radio, I think---at worst, what an absolute
treasure-trove of parts for your OWN homebrewed creation!...especially that
Eddystone dial. And we all know how rare those things have become, & what
they're going for...

At the risk of creating an impromptu auction here, I AM OPEN to
offers---there are a total of 17 detailed photos available for viewing, too.
If you're interested, please send me a direct e-mail, & I'll forward same to
you in 3-4 separate e-mails, to prevent mutual servers from getting bogged
down...

Thanks for your interest & the bandwidth, & my very

~73!~ Eddy VE3CUI - VE3XZ


From hbr@mailman.qth.net  Sun Apr  6 18:05:39 2003
From: hbr@mailman.qth.net (Michael Janis)
Date: Sun, 06 Apr 2003 13:05:39 -0400
Subject: [HBR] Homebrewed Receiver Available...
References: <001601c2fc55$e6e6cba0$d6d549c6@greg>
Message-ID: <3E905E63.142402D6@ptd.net>

Hi Eddy
I am interested in your  "HBR". Please send the photos and what you think you want
for the radio.
Thanks
Mike KE3OQ/VE4EW

Eddy Swynar wrote:

> Greetings All,
>
> If you've ever longed to find a homebrewed receiver of your own at different
> swap meets but were unsuccessful, here's a chance to bring out the best
> "...tinkerer & experimenter" within you...
>
> Not long ago, I purchased a home made 13-tube rig passed down to an
> out-of-town fellow Amateur. The receiver intrigued me because---YES!!!---the
> original builder incorporated that famous EDDYSTONE slide rule dial. It
> works on 40-meters well enough (I just listened to a bunch of AM'ers up in
> the north-east on 7290), but the other bands are dead...obviously needs some
> TLC to get them going. But the radio apparently is capable of tuning all of
> the traditional bands (judging by the markings on the dial & bandswitch),
> INCLUDING 160-meters...
>
> The beast weighs 30 pounds, & was built behind a standard 19" rack
> front---the depth of it is 14". The knobs---with the exception of the main
> tuning---are AR-88/RCA-style in appearance.
>
> The receiver appears to have been British-inspired: I thought it may have
> been the "G2DAF Communication Receiver", which was featured in the RSGB
> BULLETIN of July-November 1960, & March-April 1961, but the builder
> apparently utilized L/C networks (as opposed to crystals) in the local
> oscillators/BFOs.
>
> I don't think this is any sort of an HBR, because of the obvious English
> references on some of the parts, per my photos.
>
> I'd like to sell this radio without the hassles of eBay. It's a good
> foundation for a quality radio, I think---at worst, what an absolute
> treasure-trove of parts for your OWN homebrewed creation!...especially that
> Eddystone dial. And we all know how rare those things have become, & what
> they're going for...
>
> At the risk of creating an impromptu auction here, I AM OPEN to
> offers---there are a total of 17 detailed photos available for viewing, too.
> If you're interested, please send me a direct e-mail, & I'll forward same to
> you in 3-4 separate e-mails, to prevent mutual servers from getting bogged
> down...
>
> Thanks for your interest & the bandwidth, & my very
>
> ~73!~ Eddy VE3CUI - VE3XZ
>
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
>
> Retrieve reflector archived data via http://mailman.qth.net/mailman/listinfo/hbr


From hbr@mailman.qth.net  Tue Apr  8 19:52:06 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 8 Apr 2003 13:52:06 -0500
Subject: [HBR] Fw: Fw: Fw: RE: Fw: GB> RE: PULLEN MIXER
Message-ID: <20030408.135211.-308339.3.windy10605@juno.com>

I sent this note out in response to some discussions on designing a
modern tube (or hybrid) receiver. Several people have already 
signed onto the HBR reflector as a result. There is still quite a bit 
of interest in good tube receiver performance. 

Keep up the good work Walt. Would it be OK with you to combine 
your HBR2K notes and those from Jim and others into a section on 
the HBR Web Site ?

73  Kees K5BCQ

--------- Forwarded message ----------
From: windy10605@juno.com
To: glowbugs@piobaire.mines.uidaho.edu
Date: Tue, 8 Apr 2003 09:01:50 -0500
Subject: Fw: RE: Fw: GB> RE: PULLEN MIXER
Message-ID: <20030408.090153.-308339.0.windy10605@juno.com>

Yes, that one (couldn't find it), "An Experimental Receiver for 75m DX 
Work" by W1KLK in the Feb 1972 issue of QST, and "High Quality Hybrid
Receiver" by VE1ADH in Feb 1968 issue of 73 also have some good ideas.

On a more recent note, Walt Hutchens KJ4KV is developing a HBR2K
receiver (modern tube HBR) and is describing the effort ......pullen
mixers,  numerous improvements, what he tried, what worked and didn't, 
with many additional ideas and input from Jim N2EY. So far Walt has 
written chapters 1-15.  Check them out in the HBR Receiver archives. 

Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr
  
73  Kees K5BCQ

--------- Forwarded message ----------
From: "W1EOF" <w1eof@hamnutz.com>
To: "Prof. Arnaldo Coro Antich" <inforhc@enet.cu>,
         "_LIST:GlowBugs" <glowbugs@piobaire.mines.uidaho.edu>
Date: Sun, 6 Apr 2003 21:44:56 -0400
Subject: RE: Fw: GB> RE: PULLEN MIXER
Message-ID: <NCBBJCLPMKDDBBMEAPOHIELBLJAB.w1eof@hamnutz.com>

You just reminded me of a time back in the early 70s (???) QST had an
article on the Ultimate receiver, based on tubes. I wish I could find
that
article... I'll search their index to at least locate the year/issue. I
believe it was an 80m receiver intended to be used with a converter. Had
a
LOT of filtering, attention to intercept point, intermod, etc.

Sounded like a great receiver, I always wanted to build it.

73,

Mark W1EOF


> -----Original Message-----
> From: owner-glowbugs@piobaire.mines.uidaho.edu
> [mailto:owner-glowbugs@piobaire.mines.uidaho.edu]On Behalf Of Prof.
> Arnaldo Coro Antich
> Sent: Saturday, April 05, 2003 3:00 PM
> To: AAF-Radio-1@cox.net
> Cc: GLOW
> Subject: Re: Fw: GB> RE: PULLEN MIXER
>
>
> Oh amigo, it seems like we have run the same race a number of times !!!
> The RUSSIAN equivalent is the 6H23P.
> Designing the ideal HF receiver , I will always use an ECC88 or ECC189
> cascode RF amplifier, another one as the PULLEN MIXER, and a 12AT7
crystal
> oscillator and cathode follower... At the input, bandpass tuneable COHN
> filters ( bottom coupled )...
> As a matter of fact, I am just going to stop writing this and start
> collecting the parts for that DESIGNERS DREAM FRONT END... and after
> assembling it I will run tests using it ahead of a receiver that will
tune
> from 2 to 4 megaHertz...
> A 0 to 60 dB attenuator also at the input !!!
> Does anyone has any other ideas to add to the DESIGNERS DREAM
> FRONT END ???
> ( Manual RF gain control ?? )
> ( Bandpass 2 to 4 megaHertz filter as the coupling element for the
PULLEN
> MIXER to provide the output to the variable IF ??? )
> OH YES ! It could be a nice UP CONVERTER TOO, so that the IF will
> tune from
> 30 to 34 mHz or something like that , but the simpler approach is
> better and
> images won't be so bad with the nice RF bandpass filter at the input
!!!
> 73 and DX
> Arnie Coro
> CO2KK
> ----- Original Message -----
> From: "Mike Hanz" <AAF-Radio-1@cox.net>
> To: "Prof. Arnaldo Coro Antich" <inforhc@enet.cu>
> Cc: "GLOW" <glowbugs@piobaire.mines.uidaho.edu>
> Sent: Sunday, April 06, 2003 3:33 PM
> Subject: Re: Fw: GB> RE: PULLEN MIXER
>
>
> > Yes, of course - I neglected to insert the 6ES8 European designation
-
> > ECC189.  My apologies for the oversight.
> >
> > Prof. Arnaldo Coro Antich wrote:
> > > The 6ES8 was originally designed for
> > > a cascode amplifier used in TV tuners ?
> > > There is an excellent European vacuum tube series , ECC88, ECC189
> > > that in my opinion are the best ever made for the cascode
> configuration.
> I
> > > understand they used a peculiar structure for the grid that
> received the
> > > name of ""frame grid"" because the very thin grid wires could then
be
> placed
> > > very close to the other electrodes without fear of a short circuit.
> >
> >
>

From hbr@mailman.qth.net  Thu Apr 10 21:16:11 2003
From: hbr@mailman.qth.net (Eddy Swynar)
Date: Thu, 10 Apr 2003 16:16:11 -0400
Subject: [HBR] Last Call For  Homebrewed Receiver...
Message-ID: <005701c2ff9e$1dcbb400$dbd549c6@greg>

Hi Guys,

I received more than a few requests for photos of this rig, & a couple of
people expressed interest in acquiring it, but nothing (apparently!)
firm...yet.

Last chance to stand up & be counted---other newly-incorporated shack
expenses here (like a new/old Viking II, Model 122 clone, etc.!) are
straining my fun money budget...& besides, I realize that I just don't have
the committment to see this project through to the end it so richly
deserves.

Let me know, with my thanks in advance for your time & the bandwidth...

~73~ Eddy VE3CUI - VE3XZ




----- Original Message -----
From: "Eddy Swynar" <gswynar@durham.net>
To: <hbr@mailman.qth.net>
Sent: Sunday, April 06, 2003 12:01 PM
Subject: Homebrewed Receiver Available...


> Greetings All,
>
> If you've ever longed to find a homebrewed receiver of your own at
different
> swap meets but were unsuccessful, here's a chance to bring out the best
> "...tinkerer & experimenter" within you...
>
> Not long ago, I purchased a home made 13-tube rig passed down to an
> out-of-town fellow Amateur. The receiver intrigued me
because---YES!!!---the
> original builder incorporated that famous EDDYSTONE slide rule dial. It
> works on 40-meters well enough (I just listened to a bunch of AM'ers up in
> the north-east on 7290), but the other bands are dead...obviously needs
some
> TLC to get them going. But the radio apparently is capable of tuning all
of
> the traditional bands (judging by the markings on the dial & bandswitch),
> INCLUDING 160-meters...
>
> The beast weighs 30 pounds, & was built behind a standard 19" rack
> front---the depth of it is 14". The knobs---with the exception of the main
> tuning---are AR-88/RCA-style in appearance.
>
> The receiver appears to have been British-inspired: I thought it may have
> been the "G2DAF Communication Receiver", which was featured in the RSGB
> BULLETIN of July-November 1960, & March-April 1961, but the builder
> apparently utilized L/C networks (as opposed to crystals) in the local
> oscillators/BFOs.
>
> I don't think this is any sort of an HBR, because of the obvious English
> references on some of the parts, per my photos.
>
> I'd like to sell this radio without the hassles of eBay. It's a good
> foundation for a quality radio, I think---at worst, what an absolute
> treasure-trove of parts for your OWN homebrewed creation!...especially
that
> Eddystone dial. And we all know how rare those things have become, & what
> they're going for...
>
> At the risk of creating an impromptu auction here, I AM OPEN to
> offers---there are a total of 17 detailed photos available for viewing,
too.
> If you're interested, please send me a direct e-mail, & I'll forward same
to
> you in 3-4 separate e-mails, to prevent mutual servers from getting bogged
> down...
>
> Thanks for your interest & the bandwidth, & my very
>
> ~73!~ Eddy VE3CUI - VE3XZ
>


From hbr@mailman.qth.net  Sat Apr 12 18:43:42 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sat, 12 Apr 2003 13:43:42 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4
In-Reply-To: <3E73ACDD.6801.137A014@localhost>
References: <3E593391.30921.22CABBD@localhost>
Message-ID: <3E98180E.4396.E59187@localhost>

(In previous updates I struggled to figure out how to do proper 
measurements of intermod free dynamic range {IFDR} and began 
sorting out the problems.)

After perhaps a month of receiver design kindergarten revisited (note 
to self -- do not skip this grade next time) I homed in on the last 
stage before the crystal filter -- a cathode follower used as a driver 
mainly for the purpose of impedence matching.   I found that by 
changing my initial design to operate the c.f. at higher current and 
higher cathode voltage I could get the same results at the driver input 
as at the filter itself:  a third order intercept (IP3) of about 11.5 dbm 
(db above 1 milliwatt) and an IFDR of about 82 db.   By increasing 
the gain of the 1st IF stage (and decreasing that of the second to 
maintain the same overall IF gain) I pushed the IP3 up to 15.5 dbm 
without hurting the IFDR.  

An IP3 of 15.5 dbm and IFDR of 82 db is fairly respectable but of 
course there are three stages between these measurements and the 
antenna so I'm still a long, long way from a good receiver. 

Next stop, one stage earlier -- the 2nd mixer.   This stage combines 
a tunable IF signal 5520-6020 kcs with the VFO signal 8700-9200 to 
yield the fixed IF of 3180 kcs.   Measuring at the signal grid of the 
mixer (Pullen, 6ES8), I obtained an IP3 of +13 dbm (tolerable) and an 
IFDR of 65 db.   In other words, I lost nearly 20 db of dynamic range.  
Looking at what goes into the calculation of IFDR, the noise floor was 
up from -107 dbm to -84 dbm -- a 23 db increase in the receiver 
noise. 

Gee ... I think I found the next problem to work on.   Noise in this 
type of mixer can arrive by three routes:

1.  The tube itself -- some is unavoidable.

2.  The filament circuit -- since the cathode is 'hot', if the filament line 
is noisy, noise will be picked up.   This seems very unlikely because 
there's a line filter and a pi filter in the filament line to the front end 
tubes.   And since the cathode resistor is 470 ohms, the cathode is 
not extremely sensitive.

3.   The VFO.   No VFO generates a perfectly pure sine wave signal.  
For conventional oscillator circuits (PLL's have a whole new set of 
problems) there's a spectrum peaking at the nominal frequency and 
sloping away rapidly on both sides.   However, when you're looking at 
3 volts of peak (desired oscillator injection) you have to slope down 
pretty far to get below the few-microvolt level that's the tolerable 
maximum at the 3180 kcs IF.   (One volt to one microvolt = 120 db!)   

It helps that the VFO frequency is so far away from the IF -- about 9 
Mcs to about 3 Mcs -- but 120 db is still a lot.

The VFO is likely a problem.   If you disable the signal input to a 
mixer then when you also disable the oscillator input there should be 
only a slight change in the mixer output noise.   But as things stand 
now, the change is significant.   

(Even a pure oscillator signal would cause tube noise at frequencies 
3180 kcs above and below the oscillator frequency to be mixed to the 
IF so it will produce some increase.)

You can think of a VFO as a regenerative detector operating in 
oscillating mode.   We all know how a regen amplifies the tube noise 
-- that's the famous regenerative hiss.   But that hiss also modulates 
the pure sine wave you'd like to get from a VFO.   The problem can 
be minimized at the source by using a high Q tank and indeed a 
crystal oscillator causes much less trouble.   

Here we see the bite of a design compromise:  In order to get the 
oscillator to track the dial, I was forced to use a higher L/lower C 
combination than I wanted.   This is by design a relatively noisy 
oscillator.

There's yet another potential oscillator issue.   By the nature of the 
design, the VFO is about 4" from the 2nd mixer.   Each circuit is 
grounded in its own location -- the usual good practice.   But that 
means that 4" of chassis is in series with the oscillator injection.   
Bypassing the injection grid to the cathode of the stage does much 
more to reduce the output noise than does bypassing it to the 
chassis nearby, suggesting that noise voltages on the chassis are 
an issue.

Since the signal input to and output from the 2nd mixer are 
transformer coupled I can return the mixer signal grounds to the VFO 
-- the cleanest way would likely be via the shield of the RG-174 
injection cable.   At the same time I'll move the buffer plate tank 
circuit to the oscillator assembly (temporarily mounted at the mixer 
but radiation from it causes some humongous spurious responses) 
and provide a place to add a 3180 kcs trap on the oscillator output if 
needed to reduce oscillator spectrum noise. 

(Can't use an untuned buffer at 9 mcs because the stray 
capacitances are too large to allow a high enough plate impedance 
for the necessary gain unless circuit is tuned.   Another possibility is 
a filter with a peak centered on the VFO range and a notch at 3180 
kcs.   This is complicated by the need for a substantial bandwidth on 
the peak.   Note to self: study some filter design next time, too.)

This means, of course, a substantial rewiring of the 2nd mixer plus 
removing the VFO assembly: I sure could have provided better 
access to the screws that hold the darn thing in place.

I'm beginning to understand why there were few good receivers 
produced in the 1970 time frame.   Of course some of those 
designers knew a lot more about this stuff than I do so they'd have 
wasted a lot less time falling through holes in the learning curve.   
But most of the best of them were working for Collins ...

One exception -- the Drake R4C is at the top of at least one list of 
high performance receivers.   With a noise floor of -138 dbm and an 
IP3 (@20kcs spacing) of -10.5 dbm it has an IFDR of 85 db -- truly 
excellent performance for its day.   

Anyhow, it's a hobby.   I don't have a deadline, although I'd like to 
have the project sufficiently wrapped up to set it aside over the 
summer.

Walt Hutchens
KJ4KV

From hbr@mailman.qth.net  Sat Apr 12 21:11:26 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sat, 12 Apr 2003 16:11:26 EDT
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4
Message-ID: <1ee.687420f.2bc9ccee@aol.com>

In a message dated 4/12/03 1:43:55 PM Eastern Daylight Time, 
waltah@earthlink.net writes:

> After perhaps a month of receiver design kindergarten revisited (note 
>  to self -- do not skip this grade next time) I homed in on the last 
>  stage before the crystal filter -- a cathode follower used as a driver 
>  mainly for the purpose of impedence matching.   I found that by 
>  changing my initial design to operate the c.f. at higher current and 
>  higher cathode voltage I could get the same results at the driver input 
>  as at the filter itself:  a third order intercept (IP3) of about 11.5 dbm 
>  (db above 1 milliwatt) and an IFDR of about 82 db.   By increasing 
>  the gain of the 1st IF stage (and decreasing that of the second to 
>  maintain the same overall IF gain) I pushed the IP3 up to 15.5 dbm 
>  without hurting the IFDR.  

I've thought of doing that sort of thing to match an xtal filter but being 
the lazy sort I've used LC matching instead. Some sets have used a slug-tuned 
coil and capacitive voltage divider arrangement (see ARRL handbook), others a 
tuned-toroid-with-link setup. The turns on the toroid link were determined 
empirically with a Q meter. 
>  
>  An IP3 of 15.5 dbm and IFDR of 82 db is fairly respectable but of 
>  course there are three stages between these measurements and the 
>  antenna so I'm still a long, long way from a good receiver. 
>  
>  Next stop, one stage earlier -- the 2nd mixer.   This stage combines 
>  a tunable IF signal 5520-6020 kcs with the VFO signal 8700-9200 to 
>  yield the fixed IF of 3180 kcs.   Measuring at the signal grid of the 
>  mixer (Pullen, 6ES8), I obtained an IP3 of +13 dbm (tolerable) and an 
>  IFDR of 65 db.   In other words, I lost nearly 20 db of dynamic range.  
>  Looking at what goes into the calculation of IFDR, the noise floor was 
>  up from -107 dbm to -84 dbm -- a 23 db increase in the receiver 
>  noise. 

This just doesn't sound right. A 6ES8 Pullen making all that noise? 
>  
>  Gee ... I think I found the next problem to work on.   Noise in this 
>  type of mixer can arrive by three routes:
>  
>  1.  The tube itself -- some is unavoidable.
>  
>  2.  The filament circuit -- since the cathode is 'hot', if the filament 
line 
>  is noisy, noise will be picked up.   This seems very unlikely because 
>  there's a line filter and a pi filter in the filament line to the front 
end 
>  tubes.   And since the cathode resistor is 470 ohms, the cathode is 
>  not extremely sensitive.
>  
>  3.   The VFO.   No VFO generates a perfectly pure sine wave signal.  
>  For conventional oscillator circuits (PLL's have a whole new set of 
>  problems) there's a spectrum peaking at the nominal frequency and 
>  sloping away rapidly on both sides.   However, when you're looking at 
>  3 volts of peak (desired oscillator injection) you have to slope down 
>  pretty far to get below the few-microvolt level that's the tolerable 
>  maximum at the 3180 kcs IF.   (One volt to one microvolt = 120 db!)   
>  
>  It helps that the VFO frequency is so far away from the IF -- about 9 
>  Mcs to about 3 Mcs -- but 120 db is still a lot.
>  
>  The VFO is likely a problem.   If you disable the signal input to a 
>  mixer then when you also disable the oscillator input there should be 
>  only a slight change in the mixer output noise.   But as things stand 
>  now, the change is significant.   
>  
>  (Even a pure oscillator signal would cause tube noise at frequencies 
>  3180 kcs above and below the oscillator frequency to be mixed to the 
>  IF so it will produce some increase.)
>  
>  You can think of a VFO as a regenerative detector operating in 
>  oscillating mode.   We all know how a regen amplifies the tube noise 
>  -- that's the famous regenerative hiss.   But that hiss also modulates 
>  the pure sine wave you'd like to get from a VFO.   The problem can 
>  be minimized at the source by using a high Q tank and indeed a 
>  crystal oscillator causes much less trouble.   
>  
>  Here we see the bite of a design compromise:  In order to get the 
>  oscillator to track the dial, I was forced to use a higher L/lower C 
>  combination than I wanted.   This is by design a relatively noisy 
>  oscillator.
>  
>  There's yet another potential oscillator issue.   By the nature of the 
>  design, the VFO is about 4" from the 2nd mixer.   Each circuit is 
>  grounded in its own location -- the usual good practice.   But that 
>  means that 4" of chassis is in series with the oscillator injection.   
>  Bypassing the injection grid to the cathode of the stage does much 
>  more to reduce the output noise than does bypassing it to the 
>  chassis nearby, suggesting that noise voltages on the chassis are 
>  an issue.
>  
>  Since the signal input to and output from the 2nd mixer are 
>  transformer coupled I can return the mixer signal grounds to the VFO 
>  -- the cleanest way would likely be via the shield of the RG-174 
>  injection cable.   At the same time I'll move the buffer plate tank 
>  circuit to the oscillator assembly (temporarily mounted at the mixer 
>  but radiation from it causes some humongous spurious responses) 
>  and provide a place to add a 3180 kcs trap on the oscillator output if 
>  needed to reduce oscillator spectrum noise. 

Could the sours be part of the noise problem?
>  
>  (Can't use an untuned buffer at 9 mcs because the stray 
>  capacitances are too large to allow a high enough plate impedance 
>  for the necessary gain unless circuit is tuned.   

Cathode follower, just outside the VFO, maybe? 

>  Another possibility is 
>  a filter with a peak centered on the VFO range and a notch at 3180 
>  kcs.   This is complicated by the need for a substantial bandwidth on 
>  the peak.   Note to self: study some filter design next time, too.)
>  
>  This means, of course, a substantial rewiring of the 2nd mixer plus 
>  removing the VFO assembly: I sure could have provided better 
>  access to the screws that hold the darn thing in place.
>  
>  I'm beginning to understand why there were few good receivers 
>  produced in the 1970 time frame.   Of course some of those 
>  designers knew a lot more about this stuff than I do so they'd have 
>  wasted a lot less time falling through holes in the learning curve.   
>  But most of the best of them were working for Collins ...
>  
>  One exception -- the Drake R4C is at the top of at least one list of 
>  high performance receivers.   With a noise floor of -138 dbm and an 
>  IP3 (@20kcs spacing) of -10.5 dbm it has an IFDR of 85 db -- truly 
>  excellent performance for its day.   

The R-4C uses a frame-grid RF stage and mixer, followed by xtal filters. Only 
two stages between the antenna and the knothole, same as in my Southgate Type 
7. To avoid VFO switching, a premixer arrangement is used, which means mixer 
noise and spurs in the premixer have to be controlled. 

Another Idea:

Through the kindness of various amateurs over the years I have managed to 
acquire many of the parts to build the "Miser's Dream" receiver. 898 dial, 
390016 Oldham coupling, those 2215 kc. filters (thanks, Kees!), coil forms, 
7360s, lots of other goodies. No Polar tuning cap - yet. But I'm not too 
crazy about the front end - I think a double-tuned high Q circuit with nice 
big coils is preferable to the RF Q multiplier arrangement used in that rx. 
And the mechanical design could use a little work - build at least the front 
end on a removable plate so the thing could be used as a test bed for 7360 
vs. 6ES8 Pullen vs. 6JH8 or what have you. 

And I don't have the test gear to put numbers on how it actually performs.

Trouble is, back when I had the time and space I didn't have the parts, and 
now that I have the parts I don't have the time or space. Anybody interested 
in undertaking such a project?

73 de Jim, N2EY

From hbr@mailman.qth.net  Sat Apr 12 22:38:33 2003
From: hbr@mailman.qth.net (Mike Feher)
Date: Sat, 12 Apr 2003 17:38:33 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4
References: <3E593391.30921.22CABBD@localhost> <3E98180E.4396.E59187@localhost>
Message-ID: <001e01c3013b$de928b70$0500a8c0@eoz>

Walt -

Took my wife out to lunch so only now have a chance to respond to your post
on your re-invention of the wheel, HI. I may be way off base on this, and
admittedly did not play any number games, but, it sure seems to me that a 13
dBm IP3 is pretty darn good. I have yet to think about the adequacy, one way
or another about the bottom end. Regardless, 13 dBm as you know is 20
milliwatts, measured in a wideband sense utilizing your techniques, and is
essentially equivalent to the same power integrated over the bandwidth
outside of your IF, and therefore is a heck of a lot of power. I believe
that is a lot more than most receivers will typically encounter. I plan to
look at these numbers more closely, but if 13 is what you are getting, in my
opinion right now, that is darn good. If it takes the sum of 2 X signals of
a total power equal to Y dBm (where this is equal to 13 dBm in your case )
that are out of band signals, for you to notice an inband signal that equals
13 dBm, then, again, I think you are doing real well. An often made
oversight is to look at the 1 dB compression point and equate it to the IP3
number. I do not believe you are doing that, however there is typically a 10
dB difference between the two. Maybe I have had too many 807s today, HI.
73 - Mike



Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193



----- Original Message -----
From: <waltah@earthlink.net>
To: <hbr@mailman.qth.net>
Sent: Saturday, April 12, 2003 1:43 PM
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4


> (In previous updates I struggled to figure out how to do proper
> measurements of intermod free dynamic range {IFDR} and began
> sorting out the problems.)
>
> After perhaps a month of receiver design kindergarten revisited (note
> to self -- do not skip this grade next time) I homed in on the last
> stage before the crystal filter -- a cathode follower used as a driver
> mainly for the purpose of impedence matching.   I found that by
> changing my initial design to operate the c.f. at higher current and
> higher cathode voltage I could get the same results at the driver input
> as at the filter itself:  a third order intercept (IP3) of about 11.5 dbm
> (db above 1 milliwatt) and an IFDR of about 82 db.   By increasing
> the gain of the 1st IF stage (and decreasing that of the second to
> maintain the same overall IF gain) I pushed the IP3 up to 15.5 dbm
> without hurting the IFDR.
>
> An IP3 of 15.5 dbm and IFDR of 82 db is fairly respectable but of
> course there are three stages between these measurements and the
> antenna so I'm still a long, long way from a good receiver.
>
> Next stop, one stage earlier -- the 2nd mixer.   This stage combines
> a tunable IF signal 5520-6020 kcs with the VFO signal 8700-9200 to
> yield the fixed IF of 3180 kcs.   Measuring at the signal grid of the
> mixer (Pullen, 6ES8), I obtained an IP3 of +13 dbm (tolerable) and an
> IFDR of 65 db.   In other words, I lost nearly 20 db of dynamic range.
> Looking at what goes into the calculation of IFDR, the noise floor was
> up from -107 dbm to -84 dbm -- a 23 db increase in the receiver
> noise.
>
> Gee ... I think I found the next problem to work on.   Noise in this
> type of mixer can arrive by three routes:
>
> 1.  The tube itself -- some is unavoidable.
>
> 2.  The filament circuit -- since the cathode is 'hot', if the filament
line
> is noisy, noise will be picked up.   This seems very unlikely because
> there's a line filter and a pi filter in the filament line to the front
end
> tubes.   And since the cathode resistor is 470 ohms, the cathode is
> not extremely sensitive.
>
> 3.   The VFO.   No VFO generates a perfectly pure sine wave signal.
> For conventional oscillator circuits (PLL's have a whole new set of
> problems) there's a spectrum peaking at the nominal frequency and
> sloping away rapidly on both sides.   However, when you're looking at
> 3 volts of peak (desired oscillator injection) you have to slope down
> pretty far to get below the few-microvolt level that's the tolerable
> maximum at the 3180 kcs IF.   (One volt to one microvolt = 120 db!)
>
> It helps that the VFO frequency is so far away from the IF -- about 9
> Mcs to about 3 Mcs -- but 120 db is still a lot.
>
> The VFO is likely a problem.   If you disable the signal input to a
> mixer then when you also disable the oscillator input there should be
> only a slight change in the mixer output noise.   But as things stand
> now, the change is significant.
>
> (Even a pure oscillator signal would cause tube noise at frequencies
> 3180 kcs above and below the oscillator frequency to be mixed to the
> IF so it will produce some increase.)
>
> You can think of a VFO as a regenerative detector operating in
> oscillating mode.   We all know how a regen amplifies the tube noise
> -- that's the famous regenerative hiss.   But that hiss also modulates
> the pure sine wave you'd like to get from a VFO.   The problem can
> be minimized at the source by using a high Q tank and indeed a
> crystal oscillator causes much less trouble.
>
> Here we see the bite of a design compromise:  In order to get the
> oscillator to track the dial, I was forced to use a higher L/lower C
> combination than I wanted.   This is by design a relatively noisy
> oscillator.
>
> There's yet another potential oscillator issue.   By the nature of the
> design, the VFO is about 4" from the 2nd mixer.   Each circuit is
> grounded in its own location -- the usual good practice.   But that
> means that 4" of chassis is in series with the oscillator injection.
> Bypassing the injection grid to the cathode of the stage does much
> more to reduce the output noise than does bypassing it to the
> chassis nearby, suggesting that noise voltages on the chassis are
> an issue.
>
> Since the signal input to and output from the 2nd mixer are
> transformer coupled I can return the mixer signal grounds to the VFO
> -- the cleanest way would likely be via the shield of the RG-174
> injection cable.   At the same time I'll move the buffer plate tank
> circuit to the oscillator assembly (temporarily mounted at the mixer
> but radiation from it causes some humongous spurious responses)
> and provide a place to add a 3180 kcs trap on the oscillator output if
> needed to reduce oscillator spectrum noise.
>
> (Can't use an untuned buffer at 9 mcs because the stray
> capacitances are too large to allow a high enough plate impedance
> for the necessary gain unless circuit is tuned.   Another possibility is
> a filter with a peak centered on the VFO range and a notch at 3180
> kcs.   This is complicated by the need for a substantial bandwidth on
> the peak.   Note to self: study some filter design next time, too.)
>
> This means, of course, a substantial rewiring of the 2nd mixer plus
> removing the VFO assembly: I sure could have provided better
> access to the screws that hold the darn thing in place.
>
> I'm beginning to understand why there were few good receivers
> produced in the 1970 time frame.   Of course some of those
> designers knew a lot more about this stuff than I do so they'd have
> wasted a lot less time falling through holes in the learning curve.
> But most of the best of them were working for Collins ...
>
> One exception -- the Drake R4C is at the top of at least one list of
> high performance receivers.   With a noise floor of -138 dbm and an
> IP3 (@20kcs spacing) of -10.5 dbm it has an IFDR of 85 db -- truly
> excellent performance for its day.
>
> Anyhow, it's a hobby.   I don't have a deadline, although I'd like to
> have the project sufficiently wrapped up to set it aside over the
> summer.
>
> Walt Hutchens
> KJ4KV
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
>
> Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr
>
>


From hbr@mailman.qth.net  Sun Apr 13 02:12:35 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sat, 12 Apr 2003 21:12:35 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4
In-Reply-To: <1ee.687420f.2bc9ccee@aol.com>
Message-ID: <3E988143.29799.C8C80C@localhost>

Re my use of a cathode follower to drive the crystal filter, Jim said:

> I've thought of doing that sort of thing to match an xtal filter but being
> the lazy sort I've used LC matching instead. Some sets have used a
> slug-tuned coil and capacitive voltage divider arrangement (see ARRL
> handbook), others a tuned-toroid-with-link setup.

One man's lazy is another's 'too hard for me.'   I tried that first, and 
tied myself in knots, trying to get a match.   With a cathode follower, 
everything can be calculated -- the source impedance is 
1/transconductance in parallel with the cathode resistor so even for a 
triode at a funny plate voltage you're in the ballpark to start.

> This just doesn't sound right. A 6ES8 Pullen making all that noise? 

I agree -- it doesn't sound right.  I'm betting that most of the noise is 
from a combination of the VFO and the unwise inclusion of 4" of 
chassis in the injection circuit.   Even microvolts of noise in the 
chassis would cause a problem and my experience is that it can 
easily be much more than that.   I think the problem is just a design 
error.   

I had a difficult layout problem in that area because the basic 
structure (where's the VFO relative to the front panel, for example) 
was designed around the use of very small devices that generate no 
heat.   The FT-101 mixers are directly adjacent to the VFO, in a 1-
1/2" alley between it and the frame of the front end coil slug tuning 
mechanism.   A tube socket barely fits and controlling VFO heating 
is a problem.   I stuck the 1st mixer there because I felt there was no 
choice -- it needed to be near its grid coil and the 1st oscillator.  The 
2nd mixer was placed a couple of inches behind the VFO because I 
thought I could get away with it.  But I might have foreseen the need 
to deal with the ground loop that my casual approach to mixer 
injection caused.

A possible alternative to grounding the mixer via the VFO is to link 
couple it.   We'll see... A lot of the noise is definitely coming from 
elsewhere and I'm pretty sure the problem can be solved.

>>  (Can't use an untuned buffer at 9 mcs because the stray
>> capacitances are too large to allow a high enough plate >  
>> impedance for the necessary gain unless circuit is tuned.   

> Cathode follower, just outside the VFO, maybe? 

I need some voltage gain.   Using a Pullen circuit in which the mixer 
tube grid is swung zero to cutoff with a tube that's remote cutoff calls 
for pretty much voltage and I'm not pushing the oscillator that hard.   
But the other half of a 12AT7 with a low-Q buffer plate tank works fine 
-- I just need a voltage gain of 3.   The tank (and everything else 
possible) needs to be in the VFO assembly to keep spurs to a 
minimum.

> And the mechanical design could use a little work - build at least
> the front end on a removable plate so the thing could be used as a
> test bed for 7360 vs. 6ES8 Pullen vs. 6JH8 or what have you. 

That needs to be a fairly large removable plate.   A triode mixer vs. a 
beam tube is comparing apples to flat paving stones -- that's why 
there are no good converstions to a beam tube mixer.   Local 
oscillator injection is higher for the beam tube and should be push-
pull; the thing has so much gain that any RF stage should have a 
gain of no more than unity and may well hurt the noise figure.   Beam 
tube output should be push-pull as well but with so much gain you 
really want single conversion if possible and you want to feed the 
mixer right into the 'knothole.'   Basically you're looking at a totally 
different design up to the last IF (may not be a 1st IF in the beam 
version!) and with a whole different set of issues and trade-offs.

> And I don't have the test gear to put numbers on how it actually 
> performs.

Well ... don't be too sure it's impossible.   The URM-25's are actually 
okay, at least within the range up to 'excellent' receiver performance; 
they run $100 and down.   (And they have the basic design needed 
to go all the way -- lots of buffering, plenty of internal isolation, no 
AGC loop.   I have to study them a little more when I get the receiver 
finished.)   Stability leaves a bit to be desired but you just let 'em 
warm up for a couple of hours.  They're a little more trouble to use 
than a first rate lab instrument but in ham work, t'was ever thus.  Add 
a home made hybrid combiner and a home made step attenuator 
(directions for both are in the *Handbook* and you're there.   

> Trouble is, back when I had the time and space I didn't have the 
> parts, and now that I have the parts I don't have the time or space. 
> Anybody interested in undertaking such a project?

I'll probably do it when this one is done, probably as a general 
coverage receiver.   But that's way too far in the future to make any 
plans now!  

Walt Hutchens
KJ4KV

From hbr@mailman.qth.net  Sun Apr 13 02:16:08 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sat, 12 Apr 2003 21:16:08 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4
In-Reply-To: <001e01c3013b$de928b70$0500a8c0@eoz>
Message-ID: <3E988218.16711.CC0A08@localhost>

Mike Feher said:

> it sure seems to me that a 13 dBm IP3 is pretty darn good. I have yet
> to think about the adequacy, one way or another about the bottom end.
> Regardless, 13 dBm as you know is 20 milliwatts, measured in a
> wideband sense utilizing your techniques, and is essentially
> equivalent to the same power integrated over the bandwidth outside of
> your IF, and therefore is a heck of a lot of power. 

At the filter driver it's around 15 dbm and 82 db IFDR -- both good 
enough for this type of receiver.   The corresponding noise floor is 
close to -110 dbm -- something around a microvolt at 50 ohms.   So 
in an ideal world I'd get back to the antenna with noise-free and 
perfectly linear stages giving a gain of maybe 10 db, yielding an IP3 
of 5 dbm at the antenna and a noise floor of -120 dbm -- about a 
quarter of a microvolt.   That would be an acceptable performance, on 
a par with the usual benchmark hollow state receivers.

But when I do measurements at earlier stages it turns out that they 
are not noise free and perfectly linear:  IP3 at the 2nd mixer is still 13 
dbm but a noise floor of -84 dbm.   (IFDR 65db).   Going all the way 
back to the antenna, -7.5 dbm IP3 (no longer +) and an IFDR of 69 
db.   The corresponding NF is -111 dbm which is not all that great 
either -- Drake R-4C, -138, R-390, -137. 

The second mixer definitely contributes too much noise.   It may 
have other problems but until the noise is dealt with, they don't 
matter very much.   Probably not the mixer's fault -- it's probably 
getting 'garbage in' as noted in my earlier post.

The sharp eyed reader will notice that my numbers are slightly 
inconsistent -- the IFDR can never get better as you go backwards 
through a receiver, but I claim to have measured 65 db at the 2nd 
mixer and 69 db at the antenna.   This is at the outer limit of the 
usual error in my measurements (due to reading the S-meter, ripple 
in the filter passband ...) but might also represent some cancellation 
of distortion.

Basically the filter driver is fine and the filter itself probably okay -- it's 
handling a good fraction of a milliwatt without problems.  (I don't know 
what the max rated power level for those things is, but that certainly 
seems reasonable.)  Improvements in this area are only possible by 
improving the 1st IF stage noise figure and I have decided not to do 
that right now because the mixer stages are so bad.   

> An often made oversight is to look at the 1 dB compression point and
> equate it to the IP3 number. 

I don't think I've made that error yet, but I have made several similar 
ones.   I believe I now have the calculation right and the numbers do 
track and behave correctly, for example, the calculated IP3 is 
consistent across a range of measurement power levels and the 
distortion power does behave in a third-order fashion.

More to follow!

Walt Hutchens 
KJ4KV

From hbr@mailman.qth.net  Sun Apr 13 06:29:12 2003
From: hbr@mailman.qth.net (W7DL)
Date: Sat, 12 Apr 2003 22:29:12 -0700
Subject: [HBR] For Sale: HBR Parts
Message-ID: <002801c3017d$9e355160$6600a8c0@Dell8200>

I have the following parts for sale originally intended for an HBR 11. I
purchased these parts new in 1964 and they have been in their boxes ever
since.

3-JW Miller No. 1710 100 kc I.F. transformers, $12.50 each
1-JW Miller No. 1711 100 kc BFO transformer, $15
1-JW Miller No. 1731 1610 kc Coupling Coil, $15


One NIB  Eddystone 598 "Full Vision Dial", $30

I also have a used, Eddystone 898 sliderule type dial installed on a 8
1/2"H x 14"W x 10"D aluminum cabinet. There are no holes in this homemade
cabinet other than those needed to secure the dial. It has a chassis inside
that is likewise without holes. $100

Shipping extra.

Wil Claus, W7DL (Seattle area)


From hbr@mailman.qth.net  Sun Apr 13 07:51:03 2003
From: hbr@mailman.qth.net (Stan Wilson)
Date: Sun, 13 Apr 2003 01:51:03 -0500
Subject: [HBR] For Sale: HBR Parts
In-Reply-To: <002801c3017d$9e355160$6600a8c0@Dell8200>
Message-ID: <000801c30189$0d0fc330$0101320a@CPU>

If available I would like to purchase the Miller IF transformers and the
BFO coil (all 100 kc)

Stan ak0b@swbell.net


-----Original Message-----
From: hbr-admin@mailman.qth.net [mailto:hbr-admin@mailman.qth.net] On
Behalf Of W7DL
Sent: Saturday, April 12, 2003 11:29 PM
To: HBR
Subject: [HBR] For Sale: HBR Parts

I have the following parts for sale originally intended for an HBR 11. I
purchased these parts new in 1964 and they have been in their boxes ever
since.

3-JW Miller No. 1710 100 kc I.F. transformers, $12.50 each
1-JW Miller No. 1711 100 kc BFO transformer, $15
1-JW Miller No. 1731 1610 kc Coupling Coil, $15


One NIB  Eddystone 598 "Full Vision Dial", $30

I also have a used, Eddystone 898 sliderule type dial installed on a 8
1/2"H x 14"W x 10"D aluminum cabinet. There are no holes in this
homemade
cabinet other than those needed to secure the dial. It has a chassis
inside
that is likewise without holes. $100

Shipping extra.

Wil Claus, W7DL (Seattle area)

************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
construction notes...... via http://www.qsl.net/k5bcq/ 

Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr


From hbr@mailman.qth.net  Sun Apr 13 19:34:47 2003
From: hbr@mailman.qth.net (Hugo W. Catta)
Date: Sun, 13 Apr 2003 14:34:47 -0400
Subject: [HBR] For Sale: HBR Parts
References: <000801c30189$0d0fc330$0101320a@CPU>
Message-ID: <003001c301eb$5cec05a0$6900a8c0@dell2000>

Hi, Stan:

I'll be glad to take all the parts.
I am abuilding an HB-65 ( hopefully ) with a twist :-)

73
Hugo
AA1XV



From hbr@mailman.qth.net  Sun Apr 13 21:54:57 2003
From: hbr@mailman.qth.net (Mike Feher)
Date: Sun, 13 Apr 2003 16:54:57 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4
References: <3E988218.16711.CC0A08@localhost>
Message-ID: <007401c301fe$f1c275c0$0500a8c0@eoz>

Walt -

How are you measuring IP3 (the 3rd order intercept point)? To the best of my
knowledge it is not a measurable quantity, but is extrapolated from other
measurements? Right now I am still having trouble with your numbers, which
of course does not make them wrong, it is just that I would like to
understand. Thanks & 73 - Mike



Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193



----- Original Message -----
From: <waltah@earthlink.net>
To: <hbr@mailman.qth.net>
Sent: Saturday, April 12, 2003 9:16 PM
Subject: Re: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4


> Mike Feher said:
>
> > it sure seems to me that a 13 dBm IP3 is pretty darn good. I have yet
> > to think about the adequacy, one way or another about the bottom end.
> > Regardless, 13 dBm as you know is 20 milliwatts, measured in a
> > wideband sense utilizing your techniques, and is essentially
> > equivalent to the same power integrated over the bandwidth outside of
> > your IF, and therefore is a heck of a lot of power.
>
> At the filter driver it's around 15 dbm and 82 db IFDR -- both good
> enough for this type of receiver.   The corresponding noise floor is
> close to -110 dbm -- something around a microvolt at 50 ohms.   So
> in an ideal world I'd get back to the antenna with noise-free and
> perfectly linear stages giving a gain of maybe 10 db, yielding an IP3
> of 5 dbm at the antenna and a noise floor of -120 dbm -- about a
> quarter of a microvolt.   That would be an acceptable performance, on
> a par with the usual benchmark hollow state receivers.
>
> But when I do measurements at earlier stages it turns out that they
> are not noise free and perfectly linear:  IP3 at the 2nd mixer is still 13
> dbm but a noise floor of -84 dbm.   (IFDR 65db).   Going all the way
> back to the antenna, -7.5 dbm IP3 (no longer +) and an IFDR of 69
> db.   The corresponding NF is -111 dbm which is not all that great
> either -- Drake R-4C, -138, R-390, -137.
>
> The second mixer definitely contributes too much noise.   It may
> have other problems but until the noise is dealt with, they don't
> matter very much.   Probably not the mixer's fault -- it's probably
> getting 'garbage in' as noted in my earlier post.
>
> The sharp eyed reader will notice that my numbers are slightly
> inconsistent -- the IFDR can never get better as you go backwards
> through a receiver, but I claim to have measured 65 db at the 2nd
> mixer and 69 db at the antenna.   This is at the outer limit of the
> usual error in my measurements (due to reading the S-meter, ripple
> in the filter passband ...) but might also represent some cancellation
> of distortion.
>
> Basically the filter driver is fine and the filter itself probably okay --
it's
> handling a good fraction of a milliwatt without problems.  (I don't know
> what the max rated power level for those things is, but that certainly
> seems reasonable.)  Improvements in this area are only possible by
> improving the 1st IF stage noise figure and I have decided not to do
> that right now because the mixer stages are so bad.
>
> > An often made oversight is to look at the 1 dB compression point and
> > equate it to the IP3 number.
>
> I don't think I've made that error yet, but I have made several similar
> ones.   I believe I now have the calculation right and the numbers do
> track and behave correctly, for example, the calculated IP3 is
> consistent across a range of measurement power levels and the
> distortion power does behave in a third-order fashion.
>
> More to follow!
>
> Walt Hutchens
> KJ4KV
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
>
> Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr
>
>


From hbr@mailman.qth.net  Mon Apr 14 00:33:46 2003
From: hbr@mailman.qth.net (R.J. Mattson)
Date: Sun, 13 Apr 2003 19:33:46 -0400
Subject: [HBR] For Sale: HBR Parts
References: <002801c3017d$9e355160$6600a8c0@Dell8200>
Message-ID: <001401c30215$2165e300$e56ddbd0@rjmattson>

Hi Wil
If you still have the 598 dial, I'll take it.
Bob Mattson...W2AMI
http://www.qrz.com/callsign/w2ami

----- Original Message -----
From: "W7DL" <wclaus@msn.com>
To: "HBR" <hbr@mailman.qth.net>
Sent: Sunday, April 13, 2003 1:29 AM
Subject: [HBR] For Sale: HBR Parts


I have the following parts for sale originally intended for an HBR 11. I
purchased these parts new in 1964 and they have been in their boxes ever
since.

3-JW Miller No. 1710 100 kc I.F. transformers, $12.50 each
1-JW Miller No. 1711 100 kc BFO transformer, $15
1-JW Miller No. 1731 1610 kc Coupling Coil, $15


One NIB  Eddystone 598 "Full Vision Dial", $30

I also have a used, Eddystone 898 sliderule type dial installed on a 8
1/2"H x 14"W x 10"D aluminum cabinet. There are no holes in this homemade
cabinet other than those needed to secure the dial. It has a chassis inside
that is likewise without holes. $100

Shipping extra.

Wil Claus, W7DL (Seattle area)

************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and
construction notes...... via http://www.qsl.net/k5bcq/

Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr



From hbr@mailman.qth.net  Mon Apr 14 01:26:37 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sun, 13 Apr 2003 20:26:37 EDT
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4
Message-ID: <103.2bce8bc6.2bcb5a3d@aol.com>

In a message dated 4/12/03 9:12:24 PM Eastern Daylight Time, 
waltah@earthlink.net writes:

> > I've thought of doing that sort of thing to match an xtal filter but being
>  > the lazy sort I've used LC matching instead. Some sets have used a
>  > slug-tuned coil and capacitive voltage divider arrangement (see ARRL
>  > handbook), others a tuned-toroid-with-link setup.
>  
>  One man's lazy is another's 'too hard for me.'   I tried that first, and 
>  tied myself in knots, trying to get a match.   With a cathode follower, 
>  everything can be calculated -- the source impedance is 
>  1/transconductance in parallel with the cathode resistor so even for a 
>  triode at a funny plate voltage you're in the ballpark to start.

Just for info, here's how I do it for high Z tube circuits matching to 
filters that want resistive terminations:

First, a suitable toroid is wound with suitable wire and tuned with a 
suitable trimmer so as to resonate at the IF. ("suitable" defined as "looks 
about right and could be obtained without too much trouble"). Number of turns 
on the toroid is noted. 

The trimmer is then removed from the circuit and the L and unloaded Q of the 
toroid measured at the IF. The equivalent R of the toroid is then calculated. 
The number of link turns is then determined from the "impedance varies as the 
turns ratio squared" formula. The link is then wound over the cold end of the 
tuned winding.

As a check, the Q of the main winding is measured with the link unterminated, 
then again with a nonreactive resistor connected across the link. The Q with 
the link terminated should be exactly half the Q with the link unterminated 
if the link turns are correct. 

Yes, there are some approximations in the process, but it has worked well for 
me.

Waddya think, sirs?

73 de Jim, N2EY

From hbr@mailman.qth.net  Mon Apr 14 03:01:58 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sun, 13 Apr 2003 22:01:58 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 4
In-Reply-To: <007401c301fe$f1c275c0$0500a8c0@eoz>
Message-ID: <3E99DE56.1823.2A4E41F@localhost>

Mike asked:

> How are you measuring IP3 (the 3rd order intercept point)? To the best of
> my knowledge it is not a measurable quantity, but is extrapolated from
> other measurements? Right now I am still having trouble with your numbers,
> which of course does not make them wrong, it is just that I would like to
> understand.

I knew someone would ask, eventually.   And given the number of 
mistakes on the way to doing it right, I'm happy to have someone 
check the method.   But I'll try to tell a complete story for those who 
are interested but (unlike Mike) not familar with this area.   

In brief, 'IP3', the intermodulation third order intercept, is the one-
figure way to compare the strong signal handling ability of one 
receiver to another -- or to itself, while under development -- without 
knowing the strength of the signals used to make the measurement.  

You can think of it as the strength (power level) of two equal input 
signals at a specified spacing that would be required to produce a 
distortion product equal in strength to the signals themselves.   
However this can't actually be measured because the receiver under 
test will overload and go into gain compression well before the point 
is reached.   Instead we test at lower levels and extrapolate to 
determine the IP3 number.

The 'intercept' is because if you plot the strength of the input signals 
the slope of the input signal is 1 and the slope of the distortion 
product is 3; the power level at which they cross is the intercept.   
And that is how it is measured -- by locating the two lines and doing 
the math (for straight lines it's not that complicated!) to determine 
where they would cross if extended.    Even the measurement isn't 
that hard -- since the slope and origin of one line is known and the 
slope of the other is also known, we need only determine how far 
apart the lines are along any horizontal line to locate the second line.

In practice I doubt anyone draws the lines.   You just plug your 
numbers into a simple formula based on the geometry and you have 
IP3.  

The '3' and 'third order' is for the distortion product we measure.   Of 
course two input signals combine in an infinite number of ways.   
However the third order combination is the worst for most practical 
receivers and all the others get better or worse along with it, so it is 
conventionally taken as the measure of receiver goodness in a strong 
signal environment.

1st order is the signals themselves.   They're not distortion products.  
2nd order is any combination of two of them -- 2xA, 2xB, A+B and A-
B.   If 'A' is at 3560 kcs and 'B' is 3580 kcs, then the second order 
products caused by mixing of these signals are at 7120, 7140, 7160 
and 20 kcs.   These, however, are so far removed from the input 
signal frequencies that any decent receiver front end should dispose 
of them.

Things get a lot more interesting when we combine three to get the 
3rd order products.   These are 2xA+B, 2xB+A, 3xA, 3xB, 2xA-B, 
and 2xB-A.    The first four are 10,700 kcs and 10,720, 10,680, and 
10,740 (again, not likely to be a problem) and 3540 and 3600.   

Whoops.   The last two are only 20 kcs each way from the input 
signals.   This is problem we might face trying to hear a weak one 
with strong stations 20 and 40 kcs away on the same side.   At 
some strength of those two stations their 3rd order distortion product 
in our receiver will blot out the station we want to hear.   However for 
a good receiver, they have to be much stronger than for a poor one.   

Now the situation of strong signals located exactly 20 and 40 kcs 
from a desired weak signal might seem so rare as to be unimportant. 
But ... what about the possibility of exactly 21 and 42 kcs?   18.4 
and 36.8 kcs?  27.333 and 54.666 kcs +/- half our filter bandwidth?   
We really have to be concerned about the sum of all those 
possibilities.   The occurance of at least some of these combinations 
is essentially certain on a crowded band -- say 40 meters in the 
evening, during a DX contest.   A 'strong' receiver has a big payoff in 
that situation.

The real situation is way too complicated to use for testing so by 
convention we measure receiver strength with exactly two signals at 
a stated spacing.   Common spacings are 2 kcs (tests the receiver 
end to end, including audio stages), 20 kcs, (tests everything up to 
the sharp filter), and 100 or 200 kcs which mostly tests the RF 
stages.  The most common single test uses 20 kcs because it's 
(usually) the stuff ahead of your filters that's gonna get you -- as in 
HBR2K, which is currently trashing the input signal in the 2nd mixer.

Those who want to see numbers on darn near every receiver you can 
think of in the last few decades, can visit: 

http://sherweng.com/table.html

Now for doing the tests -- this will be somewhat simplified.   The 
setup is two 'good' signal generators -- reasonably stable, and *with a 
pure output.*   (I use a pair of URM-25D's)   They're connected 
together through a 'hybrid combiner' -- basically a device that will add 
two signals together (a) without distorting them, and (b) without 
letting either signal generator 'see' the signal from the other.   The 
combiner is needed because nearly all signal generators are non-
linear with respect to a signal put in at the output.   And if your signal 
sources have any kind of distortion, how the heck can you measure 
distortion in a receiver?

The output of the combiner goes to a step attenuator -- typically you 
can attenuate the input signal in 1-db steps from 0 to 100 db or so.

1.  Disable one generator.   Tune the receiver (peak preselector if 
any) to the other, disable the AGC, and determine the weakest 
signal that can be heard over the receiver's internal noise.   I use the 
signal strength that will cause the audio output voltage to triple -- i.e., 
signal+noise/noise = about 10 db.   

This signal strength is the 'noise floor.'   You take the signal from the 
generator, deduct 6 db for the loss of the combiner, and deduct the 
setting on the attenuator.   Measurements are stated relative to 1 mw 
(at 50 ohms, 1 mw would be about 230,000 uV).   Adequately 
sensitive receivers range maybe -110 dbm to -140 dbm.  ('dbm' = 'db 
below 1 milliwatt).    For HBR2K, measuring at the filter driver, this 
number might be -107 dbm; call this 'NF'.

Re-enable the AGC and determine the signal strength required for a 
convenient fairly low S-meter reading.   'Fairly low' is because some 
receivers will automatically turn on an attenuator at readings of S9 
and above, which would invalidate the measurements.  This will be a 
much stronger signal than above -- on HBR2K maybe -79 dbm.   Call 
this number 'S,' for single signal.

Now tune the signal generator away by 20 kcs.  Turn on the second 
generator and tune it 40 kcs away.   These settings have to be 
accurate enough that the distortion product will be in the receiver's 
passband, preferably exactly at the same frequency you used for the 
first two measurements; a frequency counter is the most convenient 
way.   Adjust the generators for equal signal strength.   Without 
readjusting the receiver, crank the attenuation down until  the 
distortion product is at the same chosen level on the S-meter.   This 
will require a very much higher signal level -- maybe -16 dbm in my 
current testing; call this 'T', for two-tone.

The three measurements are used in the following two calculations:

IP3 = (3xT - S)/2   

Using the example figures: (3x(-16)-(-79))/2 = +15.5 dbm

IFDR = 2/3 x (IP3-NF) 

2/3 x (15.5-(-107) = ~ 82 db

IFDR says how far up you can go from the noise floor with interfering 
signals before you just start to experience interference.

The clearest discussion I've found of two-tone testing and related 
issues is at:

http://www.aoruk.com/comments.htm

My few-years-old *Handbook* attempts an explanation and even 
attempts to explain the math by reference to the geometry.   
Perhaps someone has a later handbook that does so successfully.

Guess that's it.   Thanks, Mike.  Back to the receiver!

Walt Hutchens
KJ4KV

From hbr@mailman.qth.net  Tue Apr 22 02:07:39 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Mon, 21 Apr 2003 20:07:39 -0500
Subject: [HBR] Fw: HBR-16
Message-ID: <20030421.201522.-243877.12.windy10605@juno.com>

Yep, the group is alive and well and more members are joining up
.......and there are stories everywhere. 

I've taken the liberty of copying the reflector and look forward to 
seeing you check onto the reflector, tell the others your story, and
send me the pictures to post. An interesting dial arrangement which 
would be well received by the HBR group since those 898 dials 
ARE difficult to find.

Sounds like the same type background. I became a Novice in 1960,
saw the articles in the early 60s, wrote Ted Crosby, decided on the 
HBR-12, ordered most of the parts, put everything away for college,
Army duty, married, other priorities, retired in 1998, came across 
the old Ted Crosby documentation, had lost most of the parts in 35
years, found other HBR enthusiasts on the Internet, and started the 
reflector and web site. I am still amazed at how many HBRs are still 
out there and the interest, 40+ years later.

73  Kees K5BCQ 

--------- Forwarded message ----------
From: Mobile Engineering <mobeng@mnic.net>
To: k5bcq@arrl.net
Date: Mon, 21 Apr 2003 17:37:03 -0500
Subject: HBR-16
Message-ID: <5.1.0.14.2.20030421171358.00ac2f98@pop.mnic.net>

Hi OM,

Just yesterday, Easter eve., '03, typed "HBR-16" into Yahoo and, well,
I'm 
amazed!

So, if this HBR-16 group I've just discovered is still alive, I'll check
in 
w. story, photos, copy of a hand-written letter from Ted Crosby, et al.

I've also printed out lots of stuff from the newly discovered Website 
resource and am enjoying reading it.

Briefly:
A new teen-age Novice in 1960, and having started getting QST at just
about 
the month the HBR-16 was featured, I decided to go for it and attempt 
building the Rx, frustrated as I was with the 2-tube regen/borrowed 
S-38B/borrowed S-40B. (Maybe it was finally the borrowed Gonset G-66B
which 
wowed me.)

It wasn't till ten years later (1970) with a little free time after the 
Army and before beginning a 1st career teaching H.S. that I really
finished 
up the HBR-16 and got it actually working - and did a radio club 
presentation on it. By then, I'd acquired an HRO-5, a BC-348Q, an Elmac 
PMR-8, etc.

Over the decades since I've used the HBR-16 occasionally (along with lots

of other ham gear built/bought/sold, kids raised, homes bought/sold, 
careers changed). But have never loved the tough-to-twist MCN 
dial/knob...nor its off-centered symmetry and the overall looks of the 
uncabineted Rx. I've also made some technical/circuit changes.

Winter 2002-03, I decided to give the MCN dial the heave-ho, and - having

tried unsuccessfully a couple of years back to get an Eddystone dial - I 
decided to build my own (9" long x 10-turn) slide-rule dial. The
new-dialed 
HBR's now in the finishing stages - getting the kHz. markers inked and
some 
aesthetic front-panel trim designed/installed. So, photos can be taken 
soon, I hope.

73's,

John, K0YQX

From hbr@mailman.qth.net  Sun Apr 27 14:31:01 2003
From: hbr@mailman.qth.net (Eddy Swynar)
Date: Sun, 27 Apr 2003 09:31:01 -0400
Subject: [HBR] RCA "AR-88LF" Receiver FOR SALE
Message-ID: <000901c30cc1$5bd1bf80$cad549c6@greg>

Hello All,

I am selling a very nice working example of the classic 1944-vintage RCA
"AR-88LF" shortwave communications receiver that is presently surplus to my
needs (I have two of these behemoths here---one of them has to go!)...

This particular rig was used by the Royal Canadian Air Force, under the
military designation "GR-17"---a decal atop the chassis indicates that it
was re-conditioned by Canadian Aviation Electronics Ltd. Originally designed
for rack mounting, it comes pre-installed within the rather rare AR-88LF
enclosure (this last item was located separately---it has been touched up
with semi-gloss black paint which, while not done professionally, will most
certainly NOT prove to be a source of embarassment for the new owner,
either).

It includes the often-missing red RCA medallion on the front panel, and the
semi-rare RF amplifier shield assembly...it does NOT include an S-meter (due
to wartime shortages), nor the two alignment tools normally clipped beneath
the RF amplifier stage shield assembly. The allen wrench (for the knobs) is
also AWOL, but may be readily replaced into the spring holder incorporated
into the rig with any generic tool that fits the knobs.

A complete, three-ring bound photocopy of the original manual (which
includes the schematic) is included.

Although NOT museum-calibre, cosmetically this is a nice receiver. The
tuning mechanism is superbly smooth. Electrically, the overall performance
of a rig of this vintage (even on a band like 10-meters) has to be heard &
seen to be appreciated. It is a "...plug-'n-play" affair---unless you're an
absolute fuss-budget perfectionist to the Nth degree, all you have to do is
plug in a speaker/phones, 120 VAC, an antenna (even a 6' piece of wire held
in your hand will do!) and you're away. It's sensitive, and it's loud...

This above-average, working set is ready to take its rightful position in
your classic AM station (as my original one has here). I am asking $300.00
(US), OR BEST OFFER for everything as described---and here's the good news:
I WILL PERSONALLY DELIVER THIS 100-POUND (literally!) RECEIVER TO THE TRUNK
OF YOUR CAR FOR FREE this coming Saturday 3rd May, on the occasion of the
Antique Wireless Association's annual Spring Meet being held in BLOOMFIELD,
NEW YORK. Conversely, I will pleased to deliver it to your driveway, for
free, just as long as it's at a location within a REASONABLE driving
distance of the New York State Inter-state highway between Niagara Falls,
N.Y., & Rochester, on FRIDAY 2nd May, or Saturday 3rd May...

PLEASE DO NOT ASK ME TO FEDEX/ SHIP/MAIL/U.P.S. THIS RIG ANYWHERE OUTSIDE OF
THE NIAGARA FALLS TO ROCHESTER DRIVING CORRIDOR! At an even stand alone
weight of 100 pounds, it is simply too heavy to do so. If you're out of
State, perhaps you could arrange to have one of your "W2" friends in the
area receive it from me, & to hold it for you (payment in full would be
expected upon delivery to this 3rd party).

An extensive collection of digital photos of this specific radio is
available by request through my e-mail address of gswynar@durham.net
Feel free to ask any questions as well...

Please drop me a line if you're serious about acquiring this radio---if I
receive more than one request/offer, I'll weigh all the options & let just
those parties concerned what I might ultimately decide to do with it, by
this coming Thursday 1st May at the absolute latest.

Many thanks for your interest, and for your taking the time to read this! I
am absolutely convinced that whomever it is that gets this radio, he/she
WILL be pleased with their decision to acquire it...

~73!~ Eddy VE3CUI - VE3XZ


From hbr@mailman.qth.net  Sun Apr 27 23:20:20 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sun, 27 Apr 2003 18:20:20 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 5
In-Reply-To: <3E98180E.4396.E59187@localhost>
References: <3E73ACDD.6801.137A014@localhost>
Message-ID: <3EAC1F64.53.2BC50AF@localhost>

In the last part, I had the 20 kcs intermodulation-free dynamic range 
(IFDR) up to 82.5 db measured at the input to the crystal filter driver --
 the last point at which the measurement can be done before the 
filters mostly wipe out the test signals.   At the antenna, however, 
the number was in the low 60s -- better than the (solid state) FT-101 
but only on a par with the KWM-2A transceiver.

I first looked at the the 2nd mixer performance and the possiblity of 
noise from the VFO.   Making a long story short, while the VFO 
design isn't ideal from a noise viewpoint, I don't think VFO noise is 
the issue now.   I then turned to the tube operating conditions; 
increasing the cathode resistor from the usual published value of 
about 500 ohms to 2.2k increased the IFDR at that point from mid-
60's to 76 db -- good enough for a first pass.

Gee ... That was easy.   I moved back to the 1st mixer and by 
increasing the cathode resistor there to 1.5k and changing the 
voltage divider to reduce the mixer tube current, I got an IFDR of 71db 
there and 72.5 db at the antenna.  

(I made a mistake last time: IFDR *could* improve somewhat as you 
move backward through the stages if the added selectivity takes out 
the interfering signals faster than the stages add noise.   Since the 
HBR2K uses a tunable 2nd IF and about the highest-Q coils 
practical, this slight improvement is plausable.)

So, things are improving.   The best of the well known vacuum tube 
receivers are the R-390A at 81 db and the Drake R4C at 85 db.  
There's no obvious reason not to be able to hit or even better those 
numbers.   But doing so will require another pass, starting with 
improving the performance at the filter driver.   

The 82.5 db figure at the filter driver is composed of an okay IP3 
(about 16dbm) and a crummy noise floor (about 108 db).  The noise 
floor here is set mainly by the (ballpark) 10 db attenuation of the 
signal in the crystal filters and the noise floor of the 1st 3180 kcs IF 
stage.  

I have never felt I had gotten the filter matching precisely right so that 
was next: using a scope and resistive dummy loads I tweeked the 
filter input resistor (in series with the driver to filter connection) and 
output (shunting the matching transformer).   That improved the IP3 
at the filter driver to 17.5 dbm and the IFDR to 84 db.   (A couple of 
db is about the minimum you can be really sure is a change in either 
number, due to error in reading the S-meter, ripple in the filter 
passband, and so on.)

 I don't think anything else can be done about the filter attenuation -- I 
already changed to relay switching so unnecessary losses are gone.

There are two ways to go:  back through the mixers again, trying to 
really optimize the parameters in each stage and thus carry the 84 
db IFDR back to the antenna, or forward to the 1st IF stage where a 
change to a triode circuit might make sense.  Since the second 
choice is really a job (it requires a complete rebuild of the stage 
including removing and redesigning a shield across the socket) and 
even if it worked wouldn't likely improve results at the antenna until 
the mixers were redone, I will probably hit the mixers again first.

I believe that the reason the published Pullen designs aren't optimum 
for this set is that other parameters are different.   I've got higher Q 
and higher impedence coils in the mixer plates and the oscillator 
injection in the 1st mixer is somewhat wimpy.

But another visit to the 1st IF stage is clearly in the future.   For a 
given state of tube technology almost any triode is quieter than a 
pentode (right?) and I don't need so much gain -- the 2nd IF (6EH7 
pentode) is running at less than half throttle.   Might be able to drive 
the cathode of a triode and get rid of the tuned matching transformer? 
Input impedence = 1/transconductance shunted by cathode resistor? 
So for 500 ohms and modern tubes that would be about 5:1 step 
down.

Matching a grid is the pits -- the impedence is so high that pickup of 
stray signals and feedback is a problem.   But a mismatch is very 
costly because of the filter attenuation and noise floor issue.

I'm now using the coils of the two reed relays for each filter as the 
cathode resistor for the audio output tubes -- simple, and minimum 
parts count.   I'll probably try using a switch there as a muting circuit; 
I am doing that in the AGC circuit now but fixing the long time 
constant there will require some work.

The thing is gradually shaping up.   It sounds fine, doesn't drift, 
redoing the filter switching and adding a shield there gave about 80 
db of rejection 10 kcs off frequency which is as much as the filters 
are capable of.  

Walt Hutchens
KJ4KV



From hbr@mailman.qth.net  Wed Apr 30 12:11:36 2003
From: hbr@mailman.qth.net (Eddy Swynar)
Date: Wed, 30 Apr 2003 07:11:36 -0400
Subject: [HBR] Fw: GB> RCA "AR-88LF" Receiver FOR SALE
Message-ID: <001001c30f0b$01c43a80$dbd549c6@greg>

I'm happy to advise that the old RCA rig is SOLD---it will soon be setting
up residence into its appreciative new home in "W3"-land...

Please do NOT inquire about its availability anymore! Hi Hi (unless you
simply appreciate fine rigs, & would simply like a few photographs to mull
over!).

Thanks to all who responded...

~73!~ Eddy VE3CUI - VE3XZ





---- Original Message -----
From: "Eddy Swynar" <gswynar@durham.net>
To: <glowbugs@piobaire.mines.uidaho.edu>; <hbr@mailman.qth.net>;
<baswaplist@foothill.net>; <antiquewirelessassociation@egroups.com>;
<antiquewirelessassociation@yahoogroups.com>
Sent: Sunday, April 27, 2003 9:31 AM
Subject: GB> RCA "AR-88LF" Receiver FOR SALE


> Hello All,
>
> I am selling a very nice working example of the classic 1944-vintage RCA
> "AR-88LF" shortwave communications receiver that is presently surplus to
my
> needs (I have two of these behemoths here---one of them has to go!)...
>
> This particular rig was used by the Royal Canadian Air Force, under the
> military designation "GR-17"---a decal atop the chassis indicates that it
> was re-conditioned by Canadian Aviation Electronics Ltd. Originally
designed
> for rack mounting, it comes pre-installed within the rather rare AR-88LF
> enclosure (this last item was located separately---it has been touched up
> with semi-gloss black paint which, while not done professionally, will
most
> certainly NOT prove to be a source of embarassment for the new owner,
> either).
>
> It includes the often-missing red RCA medallion on the front panel, and
the
> semi-rare RF amplifier shield assembly...it does NOT include an S-meter
(due
> to wartime shortages), nor the two alignment tools normally clipped
beneath
> the RF amplifier stage shield assembly. The allen wrench (for the knobs)
is
> also AWOL, but may be readily replaced into the spring holder incorporated
> into the rig with any generic tool that fits the knobs.
>
> A complete, three-ring bound photocopy of the original manual (which
> includes the schematic) is included.
>
> Although NOT museum-calibre, cosmetically this is a nice receiver. The
> tuning mechanism is superbly smooth. Electrically, the overall performance
> of a rig of this vintage (even on a band like 10-meters) has to be heard &
> seen to be appreciated. It is a "...plug-'n-play" affair---unless you're
an
> absolute fuss-budget perfectionist to the Nth degree, all you have to do
is
> plug in a speaker/phones, 120 VAC, an antenna (even a 6' piece of wire
held
> in your hand will do!) and you're away. It's sensitive, and it's loud...
>
> This above-average, working set is ready to take its rightful position in
> your classic AM station (as my original one has here). I am asking $300.00
> (US), OR BEST OFFER for everything as described---and here's the good
news:
> I WILL PERSONALLY DELIVER THIS 100-POUND (literally!) RECEIVER TO THE
TRUNK
> OF YOUR CAR FOR FREE this coming Saturday 3rd May, on the occasion of the
> Antique Wireless Association's annual Spring Meet being held in
BLOOMFIELD,
> NEW YORK. Conversely, I will pleased to deliver it to your driveway, for
> free, just as long as it's at a location within a REASONABLE driving
> distance of the New York State Inter-state highway between Niagara Falls,
> N.Y., & Rochester, on FRIDAY 2nd May, or Saturday 3rd May...
>
> PLEASE DO NOT ASK ME TO FEDEX/ SHIP/MAIL/U.P.S. THIS RIG ANYWHERE OUTSIDE
OF
> THE NIAGARA FALLS TO ROCHESTER DRIVING CORRIDOR! At an even stand alone
> weight of 100 pounds, it is simply too heavy to do so. If you're out of
> State, perhaps you could arrange to have one of your "W2" friends in the
> area receive it from me, & to hold it for you (payment in full would be
> expected upon delivery to this 3rd party).
>
> An extensive collection of digital photos of this specific radio is
> available by request through my e-mail address of gswynar@durham.net
> Feel free to ask any questions as well...
>
> Please drop me a line if you're serious about acquiring this radio---if I
> receive more than one request/offer, I'll weigh all the options & let just
> those parties concerned what I might ultimately decide to do with it, by
> this coming Thursday 1st May at the absolute latest.
>
> Many thanks for your interest, and for your taking the time to read this!
I
> am absolutely convinced that whomever it is that gets this radio, he/she
> WILL be pleased with their decision to acquire it...
>
> ~73!~ Eddy VE3CUI - VE3XZ


