[AMRadio] Heathkit -VF-1 low band band spread


Mike Sawyer w3slk at verizon.net
Mon Jul 11 20:33:28 EDT 2016


The VF-1 is identical to the Viking I VFO. It is a doubler on 75M so I would
look at the fundamental on 160 to see where the problem lies.

Mod-U-Lator,
Mike(y)/W3SLK



-----Original Message-----
From: AMRadio [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Rob
Atkinson
Sent: Monday, July 11, 2016 6:26 PM
To: John Coleman
Cc: Discussion of AM Radio in the Amateur Service
Subject: Re: [AMRadio] Heathkit -VF-1 low band band spread

My July ER just arrived today and there is an article in it by W1TG on
fixing problems with the VF1.  Not sure but maybe this article will provide
some clues or ideas.  He had a jumping frequency problem for one thing, and
it turned out to be the band switch.

73

Rob
K5UJ


On Thu, Jul 7, 2016 at 1:39 PM, John Coleman <jc at pctechref.com> wrote:
> Ok let me see if I can explain my problem.
> # 1
>         The VFO works and cailbrates at both ends of the 40 meter band.
> #2
>         I made sure, that I was using the large rotor plates beginning
with full mesh, and the dial set to just below the 3500 khz point.
> #3
>         I know that if you  desire to cover less band frequencies, then
the tunning capicor must be less percentage of the parrallel capacitors.
> #4
>         I have worked this thing back and forth and it all ways comes out
that the coil slug is screwed out all the way (min L) and the trim cap is
max.
> #5
>         I hit 3500 khz before I get to the low end of the dial. If I dial
lower the freq actually goes well below 3500 khz before I get down to 3500
on the dial.
> #6
>         I hit 4000 khz before the dial gets all the way to 4000 and it
continues higher if I continue to turn it untill the main tunning cap is
full un-meshed.
>
> I could take turns off of the coil and add extra capacitors across the
tunning cap.  But I just doesn't make since.  Or perhaps I could use the
smaller rotor plates (maybe that is the answer and the large rotor for the
high band).
>
> I don't think the 510 pf caps that make up the feed back divider at the
grid and cathode would be a culprit.
>
> Help,
> John, WA5BXO
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