[Hammarlund] HX-50 VFO Wobble

[Al Parker]

Hi Bill,
     Great to see you again last Sun.  It seemed too cold out there to 
stop and chat for long.  Did you get the HX-50 there?  I headed home abt 
11:15.
     Ahh -the "Drifty Fifty."  It's got a bad reputation.  I had an 
HX-50A and it was pretty stable, don't think there was much difference 
in it from the plain 50 tho'.
     Sounds like you've done most of the usual fixes.  Wish I could 
suggest more specific ones, but don't have the experience with it to do 
that. Try re-tightening all screws/grounds/fasteners if you haven't done 
that.  Try a Google search on the problem, I know it's been talked about 
a lot, maybe somebody has written something down.
     Keep us posted on your progress so it'll be in the archives somewhere.
73,

Al, W8UT
www.boatanchors.org
www.hammarlund.info

"There is nothing -- absolutely nothing -- half so much
worth doing as simply messing about in boats"
Ratty, to Mole
On 11/20/2014 6:57 PM, Bill Stewart wrote:
> GE All,
> I am trying to get an HX-50 going. I have tacked in axial 'lytics for testing,
> but have Hayseed replacements on hand. I am getting about 40 watts out
> on CW. The signal, on freq. of choice, is wobbly and drifty...not a large freq
> change, but enuf to give it a bit of a gravelly sound. Don't think it is pwr supply
> ripple, since the other osc sigs sound good.
>
> The carrier osc freqs....3035kc (used on CW) and 3038kc...both sound T9X...no wobble.
> The Hetrodyne xtal osc...for the test freq on 80m...at 13035kc sounds fine, also no wobble.
> However the VFO sig at +/-6490kc and the xmit freq of +/- 3500kc, both sound wobbly
> and drifty. I would say the wobble freq is only a shift of a few cycles...but enuf to give a
> bad sounding note...far from the other two internal signals and much worse than a rig of
> this caliber should sound. It also has a slight chirp.
>
> I have changed the VFO tube...6AU6 (V105) and replaced a few O/T resistors around the
> VFO tube. I re-heated solder joints around the VFO. Tried to polish the VFO capacitor
> wiper and de-ox'ed it. Also de-ox'ed the 6AU6 tube socket.
>
> Any one had this problem or can pass along any ideas on what the problem might be.
> Thanks for your interest...73 de Bill K4JYS
>
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