[Boatanchors] VFOs drifting

[Dave Roscoe]

This sounds as if it should be posted on April 1.
Incredible.

Dave W1DWZ




----- Original Message ----- 
From: "Steve Uhrig" <Steve at swssec.com>
To: <boatanchors at mailman.qth.net>
Sent: Wednesday, July 21, 2004 5:51 PM
Subject: [Boatanchors] VFOs drifting


> I've read with interest the posts on the Boatanchor list about the
> gentleman wanting to build a solid state VFO for his old Heathkit, and
> other's comments on VFOs drifting and solutions.
>
> Let me relate a little story.
>
> When I first got my general, around 1972 as I recall, I was a poor farm
> boy shoveling manure and doing related chores to buy radio parts.
>
> My Elmer, who only had a Tech license and couldn't operate HF (back then;
> I have no idea what privileges a Tech has now) built a Heath Cheyenne
> transmitter for the learning experience. That was a CW/AM mobile
> transmitter which used an external supply. Internal VFO, and screen
> modulation for AM instead of plate modulation.
>
> Well, I tapped off my Hunter CM20 (?) CW transmitter for power for the
> Cheyenne, coupled it with my 2B, and put it on the air.
>
> The bloody VFO drifted incredibly bad. Would walk up the band, smoothly
> and steadily. In the space of maybe 20 minutes, I'd be at the top end of
> 40 meters.
>
> I went to my Elmer for help. He admitted the thing drifted, several
> others had worked on it unsuccessfully, gave up, and that's why it was
> gifted to me.
>
> My dad, a thoroughly competent electronics engineer who had been a ham
> when he was a kid, looked at it. I seem to recall some comments he made
> that he wasn't going to re-engineer the thing from both an electrical and
> a mechanical standpoint.
>
> I played with every trick I could learn, followed stuff from the
> handbook, asked on the air. No luck.
>
> My dad, who is an old German craftsman with all things mechanical as well
> as electrical, fixed the problem for me, but in a nontraditional manner.
>
> He coupled a little square motor from a battery operated toy race car
> through a pulley and dial cord arrangement to the VFO knob, through a
> rheostat. By playing around some with the rheostat, I could make the
> motor turn the VFO down knob at about the same speed the VFO drifted up --
>  at least enough to keep me in band and let the other side track me
> easier.
>
> I used that thing for some months in that fashion.
>
> If one method doesn't work, consider another, and think outside the box!
>
> Steve WA3SWS
>
>
> *******************************************************************
> Steve Uhrig, SWS Security, Maryland (USA)
> Mfrs of electronic surveillance equip
> mailto:Steve at swssec.com  website http://www.swssec.com
> tel +1+410-879-4035, fax +1+410-836-1190
> "In God we trust, all others we monitor"
> *******************************************************************
>
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