[time-nuts] Racal 9420 OCXO
Dan Rae
danrae at verizon.net
Tue Aug 23 23:02:28 UTC 2011
On 8/23/2011 1:09 PM, GandalfG8 at aol.com 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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