[R-390] test equipment question

[Michael OBrien]

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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