[time-nuts] HP 10544A with dodgy output?

[jmfranke]

Okay, 12V on the oscillator (pin 3) and 20V on the oven (pin 14).  How much 
on the oven controller, pin 8?
Are pins 2, 4, 5, 9, and 15 grounded?  Pin 6 (EFC) should be grounded for 
initial testing.

John  WA4WDL

--------------------------------------------------
From: "Nick Foster" <bistromat at hotmail.com>
Sent: Friday, January 15, 2010 2:53 PM
To: <time-nuts at febo.com>
Subject: [time-nuts] HP 10544A with dodgy output?

>
> Hi all,
>
> I've just built a GPS-disciplined oscillator built around a 10544A, 
> somewhat in the style of the Brooks Shera unit, just to use around the 
> shack. Problem is, now that it's wired up, I notice the output is heavily 
> distorted. It's clipped on the negative side of the waveform, like an 
> emitter follower without enough headroom. The more I load the oscillator 
> output, the heavier the clipping. When I load the oscillator output with 
> 1000 ohms, spec for this unit, almost 30% of the waveform is clipped on 
> the negative side. If I don't load it at all and just put a probe on the 
> output, it looks OK, but still some flattening of the bottom half of the 
> waveform.
>
> I've got it wired up according to the datasheet, with +12V on the 
> oscillator and +20V on the heater. The grounds for the 
> oscillator/amplifier, oven controller, heater, and output are all tied 
> together.
>
> I know these are old units, and I'm wondering if this is a problem (for 
> instance in the output emitter follower amp) that others know about, 
> before I tear into it looking for a solution.
>
> Thanks for your time,
> Nick
>
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