[time-nuts] HP10544a Technical Info needed

Gerald Molenkamp geraldm at iprimus.com.au
Fri Feb 2 23:21:44 EST 2007

Hi Bruce,

You are right. I havn't checked my unit against the schematic at all. It is 
well secured calibrated and operating in my HP 5342 operating well within 
the specifications. The scanned schematic came from Leapsecond a few years 
ago, and I have not had to use it as yet. Lets hope it stays that way.



----- Original Message ----- 
From: "Dr Bruce Griffiths" <bruce.griffiths at xtra.co.nz>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Saturday, February 03, 2007 3:01 PM
Subject: Re: [time-nuts] HP10544a Technical Info needed

> Gerald Molenkamp wrote:
>> Hi Howard,
>> Please find attached a schematic of the 10544, hope it helps in anyway.
>> Regards
>> Gerald
> Gerald
> The connection of the 10K oven monitor resistor R12 in the schematic is
> incorrect.
> In this position only the very small deviations in the oven supply
> voltage due to its finite output impedance will be seen as Q4 turns on
> and off.
> The resistor should surely be connected to the junction of the
> darlington (Q4) emitter and the oven heater winding resistor??
> The datasheet clearly states that the duty cycle of the oven monitor
> varies, as is seen with working 10544As.
> Bruce
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