[R-390] 8640b gear question

Mon Feb 16 20:49:48 EST 2009

Hi, I've really enjoyed the discussion about vintage test equipment. I 
too enjoy collecting TE and working on them as much as my vintage 
radios. I am fortunate, because I've been collecting this stuff for 
years and being a big time pack-rat, I never throw ANYTHING away. But I 
am running out of room!

I have aligned many a receiver with my URM-25D. It's in semi-retirement 
at this time. My 606A gets most of the work on one bench. I have a 
storage building 1/2 full of 608 (*)s.
I bought a pretty nice 8640b off of ePay last year. While repairing the 
'fine tuning', I noticed I had some cracked gears.
One poster mentioned metal gears. Anyone have an idea where they might 
be purchased??

tnx
ron
N4UE

-----Original Message-----
From: r-390-request at mailman.qth.net
To: r-390 at mailman.qth.net
Sent: Sat, 14 Feb 2009 12:00 pm
Subject: R-390 Digest, Vol 58, Issue 22

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Today's Topics:

1. Re: test equipment question (Michael OBrien)
2. Re: test equipment question (Kim Herron)
3. test equipment question (Steve Toth)

----------------------------------------------------------------------

Message: 1
Date: Sat, 14 Feb 2009 05:51:33 -0800 (PST)
From: Michael OBrien <mikobrien at yahoo.com>
Subject: Re: [R-390] test equipment question
To: r-390 at mailman.qth.net
Message-ID: <221931.4898.qm at web53001.mail.re2.yahoo.com>
Content-Type: text/plain; charset=us-ascii

Hi All
I have 2 of the 8640b and like them How can you tell if the gears are 
cracked or
broken One of mine had been rebuilt that I bought from a guy on ebay 
that does
that kind of work

Mike

--- On Fri, 2/13/09, Cecil Acuff <chacuff at cableone.net> wrote:

> From: Cecil Acuff <chacuff at cableone.net>
> Subject: Re: [R-390] test equipment question
> To: "Tisha Hayes" <tisha.hayes at gmail.com>, r-390 at mailman.qth.net
> Date: Friday, February 13, 2009, 1:22 PM
> Actually a good HP-8640B can be had on ebay for fairly
> cheap....don't go to Fair Radio though...not the place
> to buy test gear....except maybe scopes.
>
> The 8640B is an analog sig gen but has a lock feature that
> will lock it down to the dialed up freq so no problems with
> drift. I would imagine a working example could be had for
> less than $400.
>
> I didn't like the URM-25 either and got rid of it
> quickly.... The HP-606A and a freq counter was a better
> solution and then I added the 8640...
>
> Cecil...
> ----- Original Message -----
> From: Tisha Hayes
> To: r-390 at mailman.qth.net
> Sent: Friday, February 13, 2009 11:55 AM
> Subject: Re: [R-390] test equipment question
>
>
> I know that this is broaching on heresy to mention this;
>
> I found the URM-25D to be less than helpful when compared
> to a good signal generator. It is drifty, the impedance
> matching module is a joke and it is hard to get repeatable
> results when trying to chase the performance dragon.
>
> But; if you use a good frequency reference (like the 100
> KHz calibrator and that is not waay off and WWV) you can get
> darned close to being on frequency.
>
> If you dare to dabble with the compensation screws on the
> PTO to correct linearity you need a much better frequency
> counter and signal generator. Of course, gettting used
> HP/Agilent equipment will cost you more than any one radio
> would ever sell for. You can find a really decent HP 400
> series VTVM or a Boonton that would do an excellent job on
> measuring RF levels for a song-and-a-dance.
>
> The original maintenance manuals were written around the
> inherent limitations of the test equipment available at the
> time (URM-25's). While I try to keep the filaments
> glowing and avoid transistor/IC based radios in my setup I
> do use more modern test equipment.
>
>
>
> 
-------------------------------------------------------------------------
-----
>
>
>
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------------------------------

Message: 2
Date: Sat, 14 Feb 2009 08:54:20 -0500
From: "Kim Herron" <kim.herron at sbcglobal.net>
Subject: Re: [R-390] test equipment question
To: "'Michael OBrien'" <mikobrien at yahoo.com>, <r-390 at mailman.qth.net>
Message-ID: <DFFB1E4540D740C7A1BA1366F47DEBD5 at HPa550y>
Content-Type: text/plain; charset="us-ascii"

Peel the covers off and look. If the gears are cracked, you'll see it.

Kim Herron W8ZV
www.goldenradioservice.com
kim.herron at sbcglobal.net
1-616-677-3706

-----Original Message-----
 From: r-390-bounces at mailman.qth.net 
[mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Michael OBrien
Sent: Saturday, February 14, 2009 8:52 AM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] test equipment question

Hi All
I have 2 of the 8640b and like them How can you tell if the gears are
cracked or broken One of mine had been rebuilt that I bought from a guy 
on
ebay that does that kind of work

Mike

--- On Fri, 2/13/09, Cecil Acuff <chacuff at cableone.net> wrote:

> From: Cecil Acuff <chacuff at cableone.net>
> Subject: Re: [R-390] test equipment question
> To: "Tisha Hayes" <tisha.hayes at gmail.com>, r-390 at mailman.qth.net
> Date: Friday, February 13, 2009, 1:22 PM
> Actually a good HP-8640B can be had on ebay for fairly cheap....don't
> go to Fair Radio though...not the place to buy test gear....except
> maybe scopes.
>
> The 8640B is an analog sig gen but has a lock feature that will lock
> it down to the dialed up freq so no problems with drift. I would
> imagine a working example could be had for less than $400.
>
> I didn't like the URM-25 either and got rid of it
> quickly.... The HP-606A and a freq counter was a better solution and
> then I added the 8640...
>
> Cecil...
> ----- Original Message -----
> From: Tisha Hayes
> To: r-390 at mailman.qth.net
> Sent: Friday, February 13, 2009 11:55 AM
> Subject: Re: [R-390] test equipment question
>
>
> I know that this is broaching on heresy to mention this;
>
> I found the URM-25D to be less than helpful when compared to a good
> signal generator. It is drifty, the impedance matching module is a
> joke and it is hard to get repeatable results when trying to chase 
the
> performance dragon.
>
> But; if you use a good frequency reference (like the 100 KHz
> calibrator and that is not waay off and WWV) you can get darned close
> to being on frequency.
>
> If you dare to dabble with the compensation screws on the PTO to
> correct linearity you need a much better frequency counter and signal
> generator. Of course, gettting used HP/Agilent equipment will cost 
you
> more than any one radio would ever sell for. You can find a really
> decent HP 400 series VTVM or a Boonton that would do an excellent job
> on measuring RF levels for a song-and-a-dance.
>
> The original maintenance manuals were written around the inherent
> limitations of the test equipment available at the time (URM-25's).
> While I try to keep the filaments glowing and avoid transistor/IC
> based radios in my setup I do use more modern test equipment.
>
>
>
> ----------------------------------------------------------------------
> --------
>
>
>
> ______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:R-390 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list:
> http://www.qsl.net/donate.html________________________________________
> ______________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:R-390 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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------------------------------

Message: 3
Date: Sat, 14 Feb 2009 08:06:55 -0800 (PST)
From: Steve Toth <stoth47 at yahoo.com>
Subject: [R-390] test equipment question
To: R-390 at mailman.qth.net
Message-ID: <36426.80422.qm at web62307.mail.re1.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"

Hi all
Thanks for?the inputs on test equipment.? I now have a schematic for a 
simple RF
probe to use with the VTVM, good input on choices for my next signal 
generator,
and good suggestions for an inexpensive O-scope (the info actually 
helped me
avoid what could have been a potentially bad purchase of an O-scope 
locally).?
Received some good troublshooting tips too!

-- Steve
Woodinville, WA
If you can read this, thank a teacher; if you're reading?this in 
English,
thank?a military veteran.

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