[Johnson] Hello to the List.

[Glen Zook]

There are several things that you should do to the
Heath VF-1 VFO to help with the stability and none of
them requires any rewiring!

The first thing is to replace the 6AU6 oscillator tube
with a 6AH6.  This is a direct substitution.  Heath
did this with the TX-1 Apache to stablilize the VFO
for SSB operation.  The only effect may be a slight
shift in calibration.  This is due to the fact that
the interelectrode capacitance of the 6AH6 is slightly
different from the 6AU6.  You might have to slightly
adjust the trimmer capacitors for the 160 meter band
and the 40 meter band.  The variable inductors should
not be adjusted if the calibration was correct with
the 6AU6.

The second thing is to replace the 0A2 voltage
regulator with an 0B2.  This drops the screen voltage
to 108 volts from 150 volts.  Doing such definitely
helps with the frequency stability and this requires
no wiring change.

Next you need to run the VFO from a regulated 150 volt
power supply.  "Stealing" voltage from the transmitter
will NOT be satisfactory.  Use the 0A2 removed from
the 2nd modification to regulate this voltage if you
wish.

Finally, ALWAYS let the VFO run when transmitting. 
Keying the VFO will almost always result in a "chirp"
and that is worse on 80 meters and on 20, 15, and 10
meters because the fundamental frequency is multiplied
for these bands.  Of course you have to "kill" the VFO
when receiving.

I have 2 of the Heath VF-1 VFOs and use them
occasionally.  Both have the "modifications" made and
both are very stable after about a 15 minute "warm
up".

I used an Adventurer at my fraternity house in the
early 1960s and it worked fine on CW.  A while back I
"acquired" another one which I use occasionally.

Glen, K9STH


--- "Dennis A. Deaton" <d.a.deaton at roadrunner.com>
wrote:

I'm going to use a Heathkit VF-1 VFO with these
transmitters.  Has anyone had experience with using a
VFO on these units.  I understand that the key-up
voltage on the Adventurer can reach close to
600-Volts.  It then settles down to around 450-Volts
at key-down.  Does this cause the VFO to chirp a lot? 
Should I leave the VFO keyed and just key the
transmitter?

Should I use a separate power supply for the VFO? I'd
like to hear any experience that some of you may have
had with these transmitters.











Glen, K9STH

Website:  http://k9sth.com


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