[R-390] R390 Band Switch Alignment

[Flowertime01 at wmconnect.com]

Dan,

It sounds like you have narrowed this down to a weak crystal.
Sorry I do not have an R390 manual at hand to help my memory.

The cover does come off the crystal cover deck. All the crystals do plug in.
You should try to pull the cover and clean the crystal contacts. Likely the 
cover has been off before. I do not know if the osc deck ovens are switched. In 
the R390/A the ovens are switched. If the R390 ovens are on the switched 
circuit someone may have left the oven leads unsoldered the last time the crystal 
oven cover was off.

You can get the cover off without pulling the RF deck. It just takes some 
creative work. Once you get the cover off, you mite look at all the crystal 
socket contacts and give them some cleaning. The trimmer cap may be broken or need 
cleaning. I always hated to work on the caps in the osc deck. You can pry the 
retained clip sideways off the under side, lift the cap and washer out. Clean 
every thing up and put it back together.

The crystal are used on the fundamental and harmonics. You can have one 
perform not well on one band and be OK on the harmonic. The crystals do go bad. 
Replacements are available. You will find some of them off frequency. The cal 
tones on the band will all be high or low. If the crystal is used on a harmonic 
the cal tones on that band will be twice as far off. If the crystal is just off 
frequency, that's what the zero adjust is for. If you have a weak band, then 
you may want to change the crystal.

Again this why I suggest you just play with your receiver as is for a while 
and get a feel for its behavior. You can do the clean and lube and see how many 
problems get cured with some cleaned up contacts.

Roger KC6TRU