[Milsurplus] R-392 Crystals

W7QHO at aol.com W7QHO at aol.com
Sat Dec 23 02:09:44 EST 2006


In a message dated 12/22/06 2:58:59 PM, carolew at bellatlantic.net writes:


> I've got my new R-392 up and running pretty well. A 6AJ5 with shorted
> elements was killing the audio. I replaced it and noted a big
> improvement. A weak 26A6 in the RF section was hampering sensitivity.
> 
> The 3 mhz band is dead and I'm pretty sure it's the crystals. Here are
> my questions:
> 
> 1. From the manual, it appears that the crystals for this band are Y408
> (6.2 mhZ) and Y404 (12.6 mhz). Am I correct?
> 

Joe,

Yes, those are the ones you have to check.   You can do this by pulling the 
shields off V401 and V402 which are accessible from the back of the set, 
wrapping a wire once around each of these tubes (6AJ5s) in turn and running this 
over to the antenna input on a second receiver.   For band 3, look for 12.6 mc 
(Y404) on V401 and 6.2 mc (Y408) on V402.   While you're at it might as well 
check all the rest of the crystals too.

> 
> 2. Is there a way to get at the crystals without removing the upper deck
> assembly?
> 
The crystal oscillator module is located at the rear of the main chassis 
topside. The first converter xtals can be reached by removing the small cover 
plate on the right hand side of this module.   This is facilitated by cranking the 
tuning control all the way down to the low frequency end of whatever channel 
is selected which moves the slug rack out of the way.   

To access the second converter xtals it is necessary to remove the left side 
chassis plate (about 2 doz. screws!) to get at the xtal compartment coverplate 
on the left side of the oscillator module.   It may also be necessary to 
remove the back chassis plate to get at a couple of the cover plate retaining 
screws (it's been a while and I don't remember for sure).

> 
> 3. Does anyone have plans/schematic for a power supply for an R-392? I'm
> using the home-brew supply that came with it but I'd like to build
> something a little better.
> 
You might check with Fair radio (I got one there) or the e-place for a 
suitable power supply. 

Hope this helps.

Dennis D. W7QHO
Glendale, CA
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