[time-nuts] HP 105B Modification

John Miles jmiles at pop.net
Tue Dec 8 00:28:31 UTC 2009


> Ed
>
> If it helps I can send you some LTSpice schematics so that you can
> simulate the circuit for yourself.
> The breadboards behave as predicted by the simulations at 10MHz.
>
> John Miles has done some preliminary phase noise measurements on his
> version.
>
> The transformers are wound on binocular ferrite cores.
> I used some 14mm (long) cores intended for 40MHz to 220MHz (I had some)
> operation in my breadboard which works well at 5MHz and 10Mhz.

You can also use an off-the-shelf Mini-Circuits transformer for low-power
applications.  The T13-1 was the one I tried.  I'll stick some of the plots
up on the web later tonight if possible.

Residual PN is very good with this circuit, with a broadband floor near -170
dBc/Hz at 10 MHz, and no excess 1/f noise relative to a passive mixer.

-- john, KE5FX




More information about the time-nuts mailing list