[time-nuts] Racal 9420 OCXO

GandalfG8 at aol.com GandalfG8 at aol.com
Wed Aug 24 15:03:12 UTC 2011

In a message dated 24/08/2011 00:03:19 GMT Daylight Time,  
danrae at verizon.net writes:

I don't  think Racal released circuit diagrams of any of their ovens.  I 
have  traced out the circuit of the rapid warm up oven found in a lot of  
receivers, the 9442-12 and have fixed those, there is a ceramic cap that  
frequently goes wonky.  The two 9420s I have fixed were just broken  
wires; they seem to have used PVC insulated wire which degrades...  I  
haven't done the homework on those yet.

The 9420s I have do have an  EFC input as well as a stabilised Voltage 
out to feed it, and in the  receivers I have that use it [RA1795] the 
fine setting is done from that,  coarse setting from the top adjustment.
Hi Dan
I've taken a further look at the RA1794 manual and see now that it does  
confirm a fine tune pot being available when using the 9420.
Having opened up this oscillator I find there are  connections to every pin 
on the B7G connector so will assume until proven  otherwise that it does 
meet the interface spec shown in the 1794 manual.
I suspect the comments I've seen claiming most do not have the EFC  option 
is more a case that in many installations it isn't used, which  isn't quite 
the same thing.
Thanks again for your comments.

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