[time-nuts] HP 105B Modification

[Ed Palmer]

Thanks Bruce.  This is the kind of info I was looking for.  I'll have to 
study your schematics.  The purpose of much of it isn't immediately 
obvious.  :-)

Ed

Bruce Griffiths wrote:
> Ed Palmer wrote:
>> 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
>>
> Ed
>
> Amplifiers like those shown:
> http://www.ko4bb.com/~bruce/OCXOBufferAmplifiers.html 
> <http://www.ko4bb.com/%7Ebruce/OCXOBufferAmplifiers.html>
>
> work well.
> The gain is determined by the transformer turns ratio and the emitter 
> series resistor value is chosen to set the output impedance to 50 ohms.
> RF amplifier transistors other than the 2N3904 can be used, my 
> breadboard version uses an 2N5943.
> Reverse isolation is about 40dB at 10MHz. If you need more isolation 
> just cascade 2 or 3 such amplifiers.
> However some attentiaon to the supply decoupling is required to ensure 
> that coupling via the supply doesn't degrade the reverse isolation.
> In your case a nominal gain of 3dB or so should suffice.
> If you need it +27dBm output is possible with an appropriate RF 
> transistor.
>
> Bruce
>