[time-nuts] Buffer / distribution amplifier for TCXO

[Bruce Griffiths]

Henry Hallam wrote:
> On Wed, Aug 4, 2010 at 1:50 PM, Bruce Griffiths
> <bruce.griffiths at xtra.co.nz>  wrote:
>
>    
>> The TCXO output waveform is presumably a clipped sinewave as required by the
>> SE4120L?
>>      
> I posted the waveform at
> http://www.pericynthion.org/stuff/KT3225_500mV_per_div.jpg
> Does that count as clipped sine?  If not, it seems to work anyway.
>
>    
Its something like a clipped sine albeit with some ringing as it is clipped.

It more closely resembles a low pass filtered square wave.


>> In which case a linear distribution amplifier is probably required.
>>
>> With only a ~3V supply available, options for the distribution amplifier
>> topology are somewhat limited.
>>      
> I'm making a custom board that will include the TCXO and distribution
> amplifier (as well as some digital stuff to allow the 4 receivers to
> communicate), so it can have whatever power supplies it needs.
>
>    
>> In principle you could use an emitter follower driving 4 other emitter
>> followers with a resistor in series with the emitters of the output devices
>> and the AC coupled loads to match the source to the interconnecting cable
>> impedance to minimise reflections without requiring excessive dissipation in
>> the emitter followers.
>> With the low voltage supply available, using an RF choke is series with the
>> emitter follower's emitter to ground resistor will also be useful in
>> achieving the required dynamic range.
>>      
> Thanks.
>
>
> Henry
>
>    
Bruce