[Premium-Rx] HP 8649B?

[Carcia, Frank A. HS]

    Hi All,
    I bet gears could found for this unit. I've done some searches and found
a couple of them. I turn the knobs on my unit slowly and keep the FM switch
on 5 KHz
to reduce loading. Later units used delron material.
These are supposed to be better than the nylon early units. Never go too
tight with the set screws as the loading will crack the gear. fc

-----Original Message-----
From: John Miles [mailto:jmiles at pop.net]
Sent: Wednesday, August 20, 2003 2:31 PM
To: John Perlick; Henry Kolesnik; premium-rx at ml.skirrow.org
Subject: RE: [Premium-Rx] HP 8649B?


Good point re: the gears.  The FM deviation switch and bandswitch are ganged
together with a differential drive, to allow the generator to adjust the
deviation for the number of divider stages used in each band.  This assembly
is vulnerable to a number of failures, including loss of the leaf springs on
the switches and age-induced fracturing of the plastic gears.  8640B users
should treat the bandswitch with great care -- don't turn it too quickly, or
violently crank it back and forth.  It's not much fun to work on that
assembly.
 
I'd actually be surprised if HP didn't sell most parts needed to maintain
the 8640B -- it hasn't been out of production that long, and HP/Agilent is
pretty good (better than Tek, anyway) at supporting their older gear.  But
you will pay out the nose.  Knobs are in the $40-$50 range, the last time I
ordered one, and it only gets worse from there.
 
-- john KE5FX
 

-----Original Message-----
From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org]On Behalf Of John Perlick
Sent: Wednesday, August 20, 2003 10:04 AM
To: Henry Kolesnik; premium-rx at ml.skirrow.org
Subject: Re: [Premium-Rx] HP 8649B?


Hi Hank
 
I've had several 8640's and you are right to choose one.  It is still an
extremely low noise and low distortion generator (especially on HF)  because
it uses a great cavity oscillator.  Very high Q = very low noise (incl.
phase noise).
 

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