[R-390] R-390A with deaf 3Mc band

[Randy and Sherry Guttery]

On 4/14/2012 1:26 PM, Nancy Green wrote:

>  Before I buy, I'd like to know what I'm up against.

Probably not much - fortunately one band of three eliminates some of the more serious "stuff".

>  Any ideas what would cause an R-390A to just drop one band?

First look at the signal path in figure 3-1 (if you don't have a copy of the Y2K manual - download it now. -
you can get it here: http://www.r-390a.net/Y2K-R3/index.htm ).

3Mhz RF band stage shares components with the 2&  4 Mhz bands as well - so if 2&  4 are working - that eliminates that RF stage.

That leaves the converter - notice that 3 is also common with the 20Mhz band - using the same crystal for conversion. If 20 isn't dead - then the crystal may be ok - but I'd check 20 carefully.  That crystal could be badly mis-adjusted.  If 20 is indeed OK  then the contact for the crystal on switches 401/402 would be suspect - or some other associated circuitry around the crystal for 3 (&20)Mhz.

There are other things that could be a problem - you would need to either "trace" or inject signals through the chain for those - however - none are likely a serious issue. Look for bad solder joints around Y404 (the 3/20Mhz crystal) and associated components.

Good luck on your find!
best regards...

-- 
randy guttery

A Tender Tale - a page dedicated to those Ships and Crews
so vital to the United States Silent Service:
http://tendertale.com