[Johnson] HeathKit VF-1 Viking 2 wiring

[Glen Zook]

The VF-1 is definitely "happier" with the maximum
voltage being applied at 150 volts regulated.  You can
modify the transmitter to supply 150 volts regulated
but it is MUCH simpler to use an external power
supply.  Of course using 150 volts regulated means
that the screen voltage has to be dropped to 108
volts.  Now modifying the transmitter to produce the
regulated 150 volts only applies if the transmitter
has sufficient power available.  Transmitters like the
Viking I and Viking II do have sufficient power when
they are used on CW.  But, when modulated they can
start having problems depending on how much power is
run.

The Heath DX-35 and DX-40 were the transmitters most
often used with the VF-1 and they were set up to
supply the voltages for the VFO.  Unfortunately,
neither transmitter had a power transformer that was
capable of supplying the additional load and the B+
applied to the VFO went up and down as the transmitter
was keyed.  In fact, both the DX-35 and DX-40 suffer
from power transformer failure on a regular basis even
when used with crystal control let alone with the
additional load of the VFO.  The DX-40 transformers
last a "little bit" longer than the ones in the DX-35.
 However, bad power transformers are very prevalent in
both units.

As for keying the VFO on CW:  The Johnson 122 VFO will
usually chirp when keyed and the Heath VF-1 definitely
will chirp.  Not so bad on 160 meters but still bad
enough.  A little worse when the 40 meter section is
used on 40 meters.  But, when multiplied for the
higher bands it definitely gets bad.  That is why they
should run continuously on both CW and phone (whenever
the transmitter is activated).  This is true of
virtually all of the external VFOs.

By the way, the same modifications that I suggest for
the VF-1 can be used with the Johnson 122 VFO (6AH6,
dropping the screen voltage to 108 volts, etc.) and
definitely help stabilize the frequency.

Another benefit of using a separate power supply for
the VFO is that the heater ("filament") of the VFO
tube can remain on when the transmitter is not in use.
 Keeping the heater on is done in a lot of "boat
anchor" equipment to help with the stability of the
oscillator (don't have to worry about warm-up all that
much).  Heath did this in the Apache (keep the VFO
heater on whenever the transmitter is connected to the
AC line), Hallicrafters did this starting with the
SX-101 Mark II (the tuneable oscillator heater), and
many other manufacturers did the same thing.

When both the Johnson 122 and Heath VF-1 units were
"new" the vast majority of VFOs drifted, some worse
than others.  Also, unless crystal controlled, the
vast majority of transmitters also had varying amounts
of chirp.  Again, some much worse than others.  Now
Collins units did not drift and usually did not chirp
as well.  But, almost all of the other units did.

Frankly, everyone got so used to at least a "little"
chirp that we didn't even think about it.  It required
a "bit" more chirp to be objectional.  Of course
today's equipment generally has so little chirp, if
any, that many amateur radio operators have never even
heard a "chirpy" CW signal.

Glen, K9STH


--- C E <catman351 at yahoo.com> wrote:

Are you sure about this? From what I gather, the VF-1
is essentially a copy of the 122 VFO. Several years
ago, I simply rewired the plug to fit a Vik 2. Worked
fine (except for the drift which I probably could have
fixed with your mod). 









Glen, K9STH

Website:  http://k9sth.com


       
____________________________________________________________________________________
Yahoo! oneSearch: Finally, mobile search 
that gives answers, not web links. 
http://mobile.yahoo.com/mobileweb/onesearch?refer=1ONXIC