[Boatanchors] Johnson Valiant II VFO

[Jim Wilhite]

Al your memory is pretty good.  I believe the resistor is an 
18 K resistor and can be reached by removing the side of the 
VFO box.  It is the left side when you are facing the radio 
panel that will expose the resistor..

You can just clip the resistor out leaving a bit of the lead 
wire in place then solder new insulated wire to the 
remaining pieces on the terminal board and tube socket.  You 
can then run new wires out of the hole in the chassis.  If 
you move that resistor out of the box so it can cool with 
more air moving about, you can use a 2 watt.  In my 
experience, you don't really need a 10 watt, but you can buy 
some carbon film 3 watt and it should be sufficient.  The 
real key is to get that resistor out of the closed box where 
heat does build up and destroy it.

If everything is all right with the VFO, it should not 
chirp.  But I have heard many of them in past years that 
did.  I have never explored why they do, but I have heard 
them back when they were new radios.  Completely removing 
the VFO is a bit of a challenge and to do it, you will need 
to take the panel off.  Sometimes the caps in the divider 
can be bad, they should be C 12, 13 and C 14 and 15 but that 
may not be the source of chirp.  That could be something 
near the keying tube.  If the VFO is oscillating, I would 
not go to the trouble to remove it just to explore.  You 
might create more trouble than you have.

There should be about 4 resistors associated with the keying 
tube, check their values against the book.  As I recall the 
one in series with the wiper of the pot is about 1 meg.  If 
it has gone high, then that could be part of the problem. 
The cathode of one section of the 12AU7 is attached to about 
260 volts negative through a resistor of about 18K, be sure 
it is good.  Even a dirty contact on the mode switch or 
keying pot could be the culprit.

Good luck Dave.

Jim
W5JO




> Hi Dave et al,
>    I don't see the Johnson list, so don't know what 
> responses have been
> there.
>    The Valiant/Ranger, etc., VFO's have a dropping 
> resistor in the line to
> the VR tube which is inside the VFO box IIRC.  The 
> resisitor is abt 12k or
> 15k, 2 watts, and goes high in value as it gets very hot. 
> Then the VFO
> chirps.  I can't remember if the resistor is inside or 
> outside of the box,
> but it should be mounted outside, and be a 10watter if 
> posible, at least 5w.
> Some guys have moved the VR tube out of the box, but I 
> think just getting
> the dropping resisstor out helps the drift.
>    I suspect the 122 VFO is much the same.  I've been into 
> both the Ranger
> & Valiant to make the resistor change, without removing 
> the VFO, but it's
> tight, and tough to get into it.
>    It should not chirp.  That dropping resistor usually 
> fixes the chirp.
> 73,
> Al, W8UT,
> New Bern, NC
>
>> All: I have several questions about the Valiant II VFO, 
>> inspired by the
>> exchange on the 122 VFO a bit earlier.  I've never gotten 
>> the pull out of
>> this VFO; that won't help much if I want to run the SSB 
>> adapter with it.:
>>