[time-nuts] Best phase detector / mixer for 100MHz?

[Doug Parker]

thanks Bob
 
Doug
 

________________________________
 From: Anders Time <anderstime at gmail.com>
To: time-nuts at febo.com 
Sent: Monday, 26 November 2012, 9:45
Subject: Re: [time-nuts] Best phase detector / mixer for 100MHz?
  
Thanks a lot guys for all the input!
The nist articles was a very interesting read. I have ordered the
minicircuits ZRPD-1 and will try to build the 2N2222A mixer to to see how
far that will take it. I probably also will build a low noise jfet preamp
to see if that will reduce the noise. But I probably have to go to build
myself a crosscorrelation system to be able to <-180dBc with confidence. Is
there any cheap way into cross correlation measurement, using high quality
soundcard for example? Or do I have to buy one of these big old expensive
dual FFT analyzers?
/Anders

On Fri, Nov 23, 2012 at 4:42 PM, Anders Time <anderstime at gmail.com> wrote:

> I have been using an minicircuits mixer as a phase detector for measuring
> low frequency(5-10MHz) and it is usually good enough. But when I want to
> measure 100MHz the sensitivity of the mixer decreases a lot, so when I want
> to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm
> out) oscillators the sensitivity is not good enough. I read in an old
> article by Walls, Stein et al(Design considerations in state-of-the-art
> signal processing and phase noise measurement system) that one can use two
> diodes in series in the double balanced mixer to increase the sensitivity.
> I tried this with some standard 1n5711 Schottky and the sensitivity is now
> 1V/rad, but is there a easier way to do this? /Anders
>
>
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