[time-nuts] Re: Do time nuts only use and measure 10MHz clocks?

[ghf at hoffmann-hochfrequenz.de]

Am 2022-10-06 17:10, schrieb Erik Kaashoek via time-nuts:
> In a DMTD one can use one clock send to both mixer for measuring very
> accurately  the frequency/phase difference of two clocks at roughly
> the same frequency.
> One can also imagine having two different clocks derived from the same
> reference, one for each mixer, enabling the measurement of two very
> difference clocks (such as 10MHz and 1, 5 or 100MHz) with hopefully
> equal accuracy and without having to use external dividers.
> Is this for time nuts a relevant use case?
> If yes, what other frequencies besides 10MHz (and 1PPS) are used?
> Erik.

I did 100 MHz Cesium (it's the law) vs 100 MHz hydrogen maser (phase 
noise);
at least the first, analogue stage.

DMTD has its drawback already in its name: TIME DIFFERENCE. That means
that the conversion oscillator does not cancel out completely since its
mixing results are used at different points of time in the two channels.


BTW, regarding my isolation channel for 100+ MHz:
I got new transistors from Digikey; Central Semi CXT3904 and
Diodes, Inc  DXT2222, both in SOT-89. Both good for 5 MHz, perhaps. :-(
The surprise was in the wrong direction.

There is simply a big hole between BFQ19S (too hot) and the others.
Nothing available, at least for my voltage to current converter.
And LTspice and the VNA have completely different points of view.
I tend to believe the VNA.

It will take some time to digest Peter Staric°/Eric Margan's
"Wideband Amplifiers". Gurus from the time when Tektronix was king.

Cheers, Gerhard