[Premium-Rx] RACAL 9442 OCXO

[Andrew Holme]

Adam, thanks for responding.

I've tested a third 9442 and I now beleive 'm seeing two different 
phenomena:

9916 counter with interal 9442: -70 dBc sidebands at precise 1 KHz offsets = 
breakthrough from internal divider.

Two standalone 9442 units on 1792 mounting base: -44 dBc sidebands (at 500 
Hz - 2 KHz varying with temp) after supply is momentarily interrupted.

It looks like the 9442 is fussy about how the supply is interrupted and 
restored.

Rgds,
Andrew.


----- Original Message ----- 
From: "Adam Farson" <farson at shaw.ca>
To: "Premium-Rx" <Premium-Rx at mailman.qth.net>
Sent: Thursday, August 27, 2009 8:42 PM
Subject: Re: [Premium-Rx] RACAL 9442 OCXO


> Hi Andrew,
>
> I recall designing an OCXO with a PWM heater for a VHF manpack project at
> Racal in South Africa, in 1964. It is possible that this design found its
> way into the 9442 OCXO.
>
> Cheers for now, 73,
> Adam VA7OJ/AB4OJ
>
>
> -----Original Message-----
> From: premium-rx-bounces at mailman.qth.net
> [mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of Andrew Holme
> Sent: 27-Aug-09 12:32
> To: Premium-Rx at mailman.qth.net
> Subject: [Premium-Rx] RACAL 9442 OCXO
>
> I have one of these in my RACAL 9916 UHF counter and a spare on a 1792
> mounting base.
>
> The 1 MHz STD OUT from the rear of the 9916 counter has -70 dBc sidebands 
> at
> ~ 1 KHz offsets.
>
> The spare 9442 sometimes has them (at around -40 dBc) and sometimes not!!!
> I can make them go away (or come back) by momentarily interrupting the
> supply.  It's had plenty of time to warm up and I'm only interrupting it 
> for
> a fraction of a second.
>
> Does the heater work by PWM at around 1 KHz?
>
> Any theories?
>
> TIA
>
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