[time-nuts] HP 105B Modification

[John Ackermann N8UR]

I did something similar to my HP 5065A Rb standard, which had a 10811A 
and a small plug-in card that was a digital IC doing a divide by two 
followed by a simple LC filter.  I picked off the signal right at the 
chip input with a small cap and a piece of RG-174 that went to a buffer 
amplifier (I used a two-channel prototype of the TADD-1 with a MAX-477).

It works fine, except that you need to use pretty loose coupling to 
avoid loading the signal down to the point that there's not enough for 
the divider to trigger on.

I suspect the 105 (and later 5061As that used 10811s) use the same 
divider card, and the same treatment would work.

John
----
Ed Palmer wrote:
> I was thinking more along the lines of an analog buffer, but you make a 
> good point.  And if I want a sine wave output, I could use a simple pi 
> filter to clean it up.  I have an HP 8647A RF generator that does 
> exactly that on the 10 MHz reference output.
> 
> Thanks!
> 
> Ed
> 
> john.foege at gmail.com wrote:
>> Ed,
>>
>> I have seen a hex schmitt trigger inverter used for this.
>>
>> The output of the OXCO goes into all 6 schmitt rigger inverter inputs 
>> and then on the output side you have the output leg of each inverter 
>> connected through 300 ohm resistance. Thusly you get 6 hex schmitt 
>> trigger inverters wired in parallel and with a combined output 
>> resistance of 50 ohms.
>>
>> Very simple and might be just the thing you're looking for.
>>
>> John
>> KB1FSX Sent via BlackBerry by AT&T
>>
>> -----Original Message-----
>> From: Ed Palmer <ed_palmer at sasktel.net>
>> Date: Mon, 07 Dec 2009 11:03:51 To: Time Nuts Mailing 
>> List<time-nuts at febo.com>
>> Subject: [time-nuts] HP 105B Modification
>>
>> I have a late-model 105B Oscillator that's equipped with a 10811-60109 
>> oscillator.  It seems a shame to have that nice 10 MHz source without 
>> having access to it.  I was thinking of adding a buffer amp and 
>> bringing out the 10 MHz signal.  It shouldn't be too hard, but before 
>> I reinvent the wheel, has anyone done this and do you have any 
>> suggestions or advice?
>>
>> Thanks,
>> Ed
>>   
> 
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