[time-nuts] Racal 9420 OCXO
robert8rpi at yahoo.co.uk
Wed Aug 24 20:05:32 UTC 2011
I've attached a copy of the catalogue specification for Racals OCXOs. They do have electronic trim as standard. They are used in the 9478 frequency standard. The 9478 service manual specfically states that no information on the OCXOs is provided and they must be returned to Racal or appointed agents for repair.
--- On Wed, 24/8/11, GandalfG8 at aol.com <GandalfG8 at aol.com> wrote:
From: GandalfG8 at aol.com <GandalfG8 at aol.com>
Subject: Re: [time-nuts] Racal 9420 OCXO
To: time-nuts at febo.com
Date: Wednesday, 24 August, 2011, 16:03
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.
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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