[R-390] Frequency alignment R-391

[Bill Cotter]

Mack,

As a last ditch effort, you might try opening the 
crystal holder and adding pencil lead marks 
around the round crystal element. This might 
lower the crystal frequency by providing 
additional mass to the element. Keep adding on 
both sides until the desired frequency comes into view.

I put crystals in a vice, pins clamped. Then, use 
a heat gun to melt the can sealing solder, and 
pull the can off with pliers.

I also have a homebrew crystal test instrument 
that connects to a counter and simulates the 
correct pF capacitance for crystal "tuning".

When you get it where you want it, seal her back up.

Best wishes - 73 Bill N4LG




At 10:49 AM 9/27/2020, you wrote:
>I have a R-391 that is about 3 kc high on 4 Mc. 
>I’ve tried adjusting the 1st crystal 
>oscillator variable cap but that won’t move 
>the crystal far enough. The same is true at 3 
>Mc. Any suggestions? I have restored at least a 
>dozen R-390a’s to factory specifications. I 
>have several ideas I could try but want to get 
>the collective wisdom of this group 1st please. 
>73, Mack W4AX -- 73, Mack W4AX 
>https://www.qrz.com/db/W4AX 
>______________________________________________________________ 
>R-390 mailing list Home: 
>http://mailman.qth.net/mailman/listinfo/r-390 
>Help: http://mailman.qth.net/mmfaq.htm Post: 
>mailto:R-390 at mailman.qth.net This list hosted 
>by: http://www.qsl.net Please help support this 
>email list: http://www.qsl.net/donate.html