On 8/23/2011 1:09 PM, [email protected] wrote:
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.
Nigel, I took the liberty of correcting the part number in the header.
They are quite common, also quite often go wrong, so beware if you buy
any off ebay...
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.
So yes, in theory they could be used as a basis for a GPS disciplined
standard, but a quick eBay search shows a lot of more modern and
probably better quality 10 MHz OCXOs from China...
Dan
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