[time-nuts] Racal 4920 OCXO

GandalfG8 at aol.com GandalfG8 at aol.com
Tue Aug 23 20:09:32 UTC 2011

Hi All,
This is quite a common oscillator, with variants used in a number of Racal  
receivers or offered as high stability options for Racal counters etc, but  
although the specs are widely available I've not found anything from Racal 
that  might be considered to be a user manual.
The manual for the Racal RA1794 receiver offers the connection information  
shown below.....
Table 3 : 9420 Pin Connections

1 5 MHz Output relative to pin 7
2 Internally stabilized +5.~ V  varactor
diode control voltage
3 +7.5 V stabilized monitor output
4 +12  V supply
5 Internally stablized +2.8 Voutput
6 Varactor diode  connection
7 0 V (also connected to can).

Any 4920 I've seen does match the basic RF output and DC supply connections 
 shown above, and the pin 6 information implies an option for electronic  
frequency control, but  I've also seen comments online to suggest most  units 
don't actually have electronic frequency control.
I certainly can't recall any Racal kit using one of these with an EFC  
option but if it is available I was just thinking the 4920 could make a  nice 
oscillator for a 5MHz GPSDO.
Any comments would be appreciated, and a manual and/or schematic would be  
one heck of a bonus:-)

More information about the time-nuts mailing list