[R-390] R-392 VFO End Point?

[Flowertime01 at wmconnect.com]

John,

For luck the R390/URR R390A/URR and your R392 all share the same PTO.

I think 7 KC is still well within adjustment range.

If you are 7 KC long you may be needing to open the can, undo the heater 
wires, open the inner can and change the winding on a very small coil. Or add / 
subtract some small (2PF) caps.

Watch the mail here, someone is already looking for the archive thread and 
will post that for you also.

On the front of the PTO there are two cover caps. You want the inner one on 
the right between Z702 and the shaft. Behind cover cap 1 is an end point 
adjustment.

Like Alice, one way will make you longer (taller) and the other way will make 
you shorter (smaller). Can you screw 7 KC out of that adjustment? Try it 
before you go opening cans of wires.

If you have a frequency counter you are better off. You can make adjustments 
with the PTO hanging out of the receiver. If not then you have to 
1.) remember where you are.
2.) Pull the PTO
3.) make and adjustment.
4. Remember if you went left or right
5.) put in the PTO
6.) set the PTO on one end
7.) dial off to the other end
8.) determine if this is better or not
9.) consider if next adjustment will be left or right
10.) consider how much to adjust
11.) repeat until perfect.

If you have a counter it just goes faster.

Dial the PTO to X.455 and draw a mark across the coupler and the frame.
Carefully rotate dial 
If you go the wrong way you will hit the stop before you get 10 turns.
So having learned which way to go, start over and dial it off in the correct 
direction
We think clock wise is down in frequency and counter clock wise is up in 
frequency.

Think about the KC knob and the way the frequency conversion is done.

Rotate off 10 turns, line up your mark and see what the counter reads.

Every time you change the end span adjustment, the points will move.
So make an adjustment.
Line up for the counter at X.455
Mark the dial to frame
Roll off 10 turns
Line up the mark 
Read the counter
You will either be getting closer or further off the exact 1Mhz

If you hit the end of the adjustment before you get exact there are two 
options
A.) accept what you get.
B.) Read some more help from the archives and prepare for some PTO surgery.

It is not hard to open the outer and inner can and do repairs.

Good Luck with the fix.

Roger KC6TRU