Johnson Ranger VFO advice please
bcarling at CFL.RR.COM
Sun Sep 17 19:43:13 EDT 2000
My next step would be to get some FREEZE SPRAY.
Connect a dummy load.
Monitor the VFO on a receiver nearby, but don't run a lot of power.
Aim the can at each of the frequency determining components, beginning
with the fixed resistors and capacitors. ONLY USE A SMALL SQUIRT! You don't want to
get the parts too cold or you will get massive drift!
What you are looking for is a bad connection, or other failure INSIDE a part.
You can also check for bad solder joints by this method if you squirt them
and listen too.
This technique is used more frequently with solid state equipment that has intermittent faults
but I don't see why it couldn't be used with tube gear too.
Just be aware that a sudden chilling is going to send some components into a cndition
where your frequency chjanges quite a bit from its starting point, so you may need to hunt
up the band...
When the warbling stops or changes drastically (might get worse!) - you have found the
This method is not guaranteed top work. Your mileage may vary!
Let us know how it works out for you!
On 17 Sep 00, at 14:17, Leslie Zwiebel wrote:
> I'd appreciate hints re a problem w/ my Ranger on AM:
> QSO reports on 3.870 are that FSK-like activity is heard behind my
> decent power/decent audio signal, as if I am also sending a RTTY signal
> I can hear it myself when I "Zero" in the shack using the Ranger in
> order to spot the net frequency I am hearing on my receiver.
> On-air front panel metering shows no probs.
> Helpful local AM'ers have suggested, and we have tried the
> following: inserting a crystal and running rock-bound, which eliminates
> the problem, pointing to the VFO as culprit.
> It does not occur (signal is clean) on 40M(!), so we are thinking
> about components in the 160M/80M/ loop.
> Two or three substitutes for the 6AU6 in the VFO are no help. Will
> also try a sub for the OA2 VR tube. Poking around at solder joints and
> grounds, at least the visible ones with the VFO cover off has not
> yielded any change.
> Will probably next start VOM measurements on top layer of the VFO
> Before we start taking off the panel to access further layers of the
> VFO (alot of work), I'd appreciate any ideas.
> Menlo Park, CA
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