[HBR] Where Is Everyone and expensive crystals?
Don
dkelly42 at cox.net
Sat Mar 18 15:22:11 EST 2006
One suggestion for experimentally adventurous and for eliminating
expensive crystals is to use microprocessor crystals in a ladder design.
It allows the use of same frequency crystals at a fraction of the cost
and size. Performance can be outstanding.
My last tube receiver uses Cohn type ladder filters (you can almost see
it on my QRZ picture in the PC board box). Excellent performance, can be
mounted anywhere and doesn't need sockets. I used a 6BE6 mixer. In the
mixer plate I used a tuned toroid matching transformer. I forced the
match by paralleling the high impedance primary with a fixed resistance
and the link matched the filters impedance. Same matching on the output
to the IF amplifiers. Old solid state trick. Can be done with Pi or L
networks.
The mixer coud also be followed with a cathode follower and the filter
fed from the lower cathode impedance.
Rich Arland K7SZ is familiar (famous?) name and call to us Qrpers.
With low local oscillator frequencies you can reduce spurs from
harmonics by following the LO with a double tuned band pass filter. I
built one on a small PC board. I followed my LO with a cathode follower
buffer and built the BP filter with a 500 ohm I/o impedance. It wasn't a
precaution but a necessity as I had a spur or harmonic that caused a few
spurious responses.
I like Walt's scheme. Kind of a reverse of the old ARRL 40m/80m band
image scheme. Instead of a 1.7MHz IF with a 5MHz VFO he used a
correspondingly low LO and 5.4MHz filter. Best thing is the stability
the low LO gives.
To all...good luck on your projects. The trough in the sunspot cycle is
a great time for homebrewers.
BTW, Mouser sells 5.00, 5.068, 5.185, 5.9904 MHz crystals around 40 to
60 cents each. Using 5.185 one can get both 80/40M. The LO would run
from 1.18 to 2.11MHz. But a 10 cent diode switch could be used to shift
the LO frequency for one range and allow a much more limited LO tuning.
Just an idea.
K5UOS
-----Original Message-----
From: hbr-bounces at mailman.qth.net [mailto:hbr-bounces at mailman.qth.net]
On Behalf Of hbr-request at mailman.qth.net
Sent: Saturday, March 18, 2006 1:01 AM
To: hbr at mailman.qth.net
Subject: HBR Digest, Vol 25, Issue 2
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Today's Topics:
1. Re: HBR Digest, Vol 25, Issue 1 (Rich Arland)
2. Jay's notes and letters (Rich Arland)
3. Re: Jay's notes and letters (Bill)
4. Re: Fw: [HBR] Where Is Everyone? (LeeCraner at aol.com)
5. Re: Jay's notes and letters (john)
6. 'Transformerless' receiver design (Walter A. Hutchens)
----------------------------------------------------------------------
Message: 1
Date: Fri, 17 Mar 2006 07:09:26 -0500
From: "Rich Arland" <richard.arland at verizon.net>
Subject: [HBR] Re: HBR Digest, Vol 25, Issue 1
To: <hbr at mailman.qth.net>
Message-ID: <007d01c649bb$a6609fa0$6501a8c0 at a>
Content-Type: text/plain; charset=iso-8859-1
For a while there I had forgotten I was a memeber of this list!!
Glad to see there is intelligent life out there.
I emailed walt about sharing his transformerless design as I need a
project,
I have a lot of spare time on my hands due to foot surgery on the 30th,
and
this looks like a good project to get me (and maybe some others) back
into
serious homebrewing.
73 Rich K7SZ
------------------------------
Message: 2
Date: Fri, 17 Mar 2006 07:11:10 -0500
From: "Rich Arland" <richard.arland at verizon.net>
Subject: [HBR] Jay's notes and letters
To: <hbr at mailman.qth.net>
Message-ID: <008601c649bb$e1150140$6501a8c0 at a>
Content-Type: text/plain; charset="iso-8859-1"
I would be interested in a copy, also. Please let me know what the costs
would be.
73 Rich K7SZ
------------------------------
Message: 3
Date: Fri, 17 Mar 2006 11:07:38 -0500
From: "Bill" <w2dgb at ptd.net>
Subject: Re: [HBR] Jay's notes and letters
To: "HBR Receiver List" <hbr at mailman.qth.net>
Message-ID: <002701c649dc$efa15bc0$6401a8c0 at cmts.sth.ptd.net>
Content-Type: text/plain; charset="iso-8859-1"
Let me get on the wagon here. I also would like a copy.
Bill w2dgb
----- Original Message -----
From: "Rich Arland" <richard.arland at verizon.net>
To: <hbr at mailman.qth.net>
Sent: Friday, March 17, 2006 7:11 AM
Subject: [HBR] Jay's notes and letters
I would be interested in a copy, also. Please let me know what the costs
would be.
73 Rich K7SZ
************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and
construction notes...... via http://www.qsl.net/k5bcq/
there is also a mirror (faster response)at http://k5bcq.edebris.com/
Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr
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------------------------------
Message: 4
Date: Fri, 17 Mar 2006 14:18:26 EST
From: LeeCraner at aol.com
Subject: Re: Fw: [HBR] Where Is Everyone?
To: hbr at mailman.qth.net
Message-ID: <2a4.76c3a8b.314c6582 at aol.com>
Content-Type: text/plain; charset="US-ASCII"
Kees:
How about scanning those letters and burning them on a CD?
73
Lee WB6SSW (HBR-16 restoration and documentation in the works)
------------------------------
Message: 5
Date: Fri, 17 Mar 2006 20:41:50 -0500
From: john <johnmb at nc.rr.com>
Subject: Re: [HBR] Jay's notes and letters
To: HBR Receiver List <hbr at mailman.qth.net>
Message-ID: <6.2.1.2.2.20060317204103.0245e2c0 at pop-server.nc.rr.com>
Content-Type: text/plain; charset=us-ascii; format=flowed
Add me too (I've got some original literature from Ted I could
contribute)
John K5MO
At 11:07 AM 3/17/2006, you wrote:
>Let me get on the wagon here. I also would like a copy.
>
>Bill w2dgb
>----- Original Message -----
>From: "Rich Arland" <richard.arland at verizon.net>
>To: <hbr at mailman.qth.net>
>Sent: Friday, March 17, 2006 7:11 AM
>Subject: [HBR] Jay's notes and letters
>
>
>I would be interested in a copy, also. Please let me know what the
costs
>would be.
>
>73 Rich K7SZ
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>construction notes...... via http://www.qsl.net/k5bcq/
>there is also a mirror (faster response)at http://k5bcq.edebris.com/
>
>
>Retrieve reflector archived data via
>http://mailman.qth.net/mailman/listinfo/hbr
>
>
>
>
>--
>No virus found in this incoming message.
>Checked by AVG Free Edition.
>Version: 7.1.385 / Virus Database: 268.2.3/281 - Release Date: 3/14/06
>
>
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>construction notes...... via http://www.qsl.net/k5bcq/
>there is also a mirror (faster response)at http://k5bcq.edebris.com/
>
>
>Retrieve reflector archived data via
>http://mailman.qth.net/mailman/listinfo/hbr
>
>
>--
>No virus found in this incoming message.
>Checked by AVG Free Edition.
>Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date:
3/17/2006
--
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 3/17/2006
------------------------------
Message: 6
Date: Fri, 17 Mar 2006 22:29:46 -0500
From: "Walter A. Hutchens" <waltah at earthlink.net>
Subject: [HBR] 'Transformerless' receiver design
To: hbr at mailman.qth.net
Message-ID: <441B385A.16138.3BCF3FD at localhost>
Rich said:
> I emailed walt about sharing his transformerless design as I need a
> project, I have a lot of spare time on my hands due to foot surgery on
the
> 30th, and this looks like a good project to get me (and maybe some
others)
> back into serious homebrewing.
I've had a couple of requests for this info. I've been writing it up
as the
project went along and have started on the diagram. I don't think it
would
be a good beginner's project because the IF packs quite a bit of gain
into
two stages and if there's any feedback at all, the shape of the bandpass
will be crummy. That has to be the case because there's no RF stage.
Additionally, the 'six tubes plus rectifier' is really ten when you
allow for
dual-section tubes with the halves doing separate jobs -- but packed
into six
sockets plus one.
'Transformerless' design gives you new issues that I think I have
completely
resolved (and documented) but that isn't a guarantee. However someone
who has build a several-tube design before should be able to get it
working.
I should have a diagram in a week. I think I can resurrect a computer
that
will let me do a final version with software.
Critical parts are three shielded coil forms 9/32" diameter with about
an
inch of winding space and four terminals (I used APS-13/APN-1 IFTs) plus
one spare shield and base to house the crystal filter, a double gang BC
receiver tuning cap, each section about 450 mmf (otherwise other values
will have to be adjusted) with fairly low torque, another double gang BC
tuning cap with equal sections, value >200 mmf/section, ideally with a
built-
in 5:1 reduction, plus the usual main tuning dial (5:1 is NOT a high
enough
ratio -- I used one of the two-speed Miller drives) and other usual
receiver
parts. Three crystals that will have to be special ordered -- most of
$75
for those. Most tubes are uncommon but all are cheap.
Walt
KJ4KV
------------------------------
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