[time-nuts] HP 10811A failure

Adrian rfnuts at arcor.de
Sat Oct 13 11:30:27 EDT 2012


At least not a power supply cap. No change on a different PS. Do you 
mean the oscillator output coupling cap?

12V for the oven because inside the outer oven lives a 10811-60158 ( see 
http://www.realhamradio.com/GPS-oven-journey.htm ) that, as by the specs 
sheet, is specified 12 to 30 V DC, 11 W max. at turn on (mine draws some 
9 W), and Steady state power drops to approximately 2 W at 25°C in still 
air at 20 V (mine draws some 1.9 W at 12 V without powering the outer oven).

Adrian


Azelio Boriani schrieb:
> And, why 12V for the oven? The 10811A manual states from 20V to 30V for the
> oven. 12V for the oscillator itself.
>
> On Sat, Oct 13, 2012 at 4:34 PM, Tom Knox <actast at hotmail.com> wrote:
>
>> Sounds like another dead cap.
>>
>> Thomas Knox
>>
>>
>>
>>> Date: Sat, 13 Oct 2012 14:51:54 +0200
>>> From: rfnuts at arcor.de
>>> To: time-nuts at febo.com
>>> Subject: [time-nuts]  HP 10811A failure
>>>
>>> Hi All,
>>>
>>> both of my double oven 10811A's have been running flawlessly until now
>>> when I noticed that the output power has dropped by about 3 dB (measures
>>> only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by
>>> about 20 dB, while the frequency is still spot on.
>>>
>>> I used them for various mesurements, so I can unfortunately not remember
>>> what might have caused the failure. Only the 12V linear lab power supply
>>> that fed the heaters had developed a completely dead filter cap, so the
>>> feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear
>>> to be still working though. I'm only using the internal heater. They
>>> draw some 700 mA at power up and drop to around 150 mA  each when warm.
>>> So the oscillators are unlikely to be cooked inside. Something must have
>>> happened to the 10 MHz output, possibly an ESD issue?
>>>
>>> Before I start taking them apart, can anyone tell what has happened or
>>> what to look for first?
>>>
>>> Regards,
>>> Adrian
>>>
>>>
>>>
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