Re: 10 MHz Reference Distribution Amplifier

Neil Smith G4DBN

I have some of Dave's units, and I've tried a few others, but always seem to hit a problem with inter-port crosstalk and noisy instruments polluting the reference though poor rejection of signals going into the outputs.  Some of that is caused by noise on the outer of the BNC connectors from power supply currents and earth returns going through the coax into the reference box instead of all through the proper returns.  For anything critical, I now use isolation transformers and shielded twisted pair to distribute the reference signals.  The effects are tiny, but if you have a raging SMPS moving tens of amps around, it doesn't take much current going along the coax brais to the distribution amp and back to the supply ground to modulate other outputs to the point where the reference starts producing spurs at the -80dBc level.

I did consider using fibre to distribute the reference, but there's a lot more places where noise and jitter and crosstalk show up. Nice shielded passive baluns and balanced amplifiers with excellent reverse attenuation is my go-to solution for now.

Neil G4DBN

On 21/03/2021 18:25, Colin Ranson wrote:

At 10 MHzI have used the G4HUP Distribution amplifier in the past and now I use a Mini-circuits ZFSC splitter, unused SMA outputs  terminated with 50ohm.




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From: Jules - M0UGA
Sent: 21 March 2021 18:07
Subject: Re: [UKMicrowaves] 10 MHz Reference Distribution Amplifier


SV1AFN also does a nice one. Just like everything from him it's beautifully made although not necessarily the cheapest.


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