Re: 10 MHz Reference Distribution Amplifier
I stopped using my HUP Dist-amp because of just that and also plugging something in altered the output level on the others, I never bothered to find out why. Until recently I have been using the Mini-Circuits splitter to feed my 23/13/9cm SG-Labs transverters.....(mine are stable enough without, it was just because I could)...... until I found my Chinese GPS has gone boobs up and was just outputting the OCXO frequency even though the LED said it was locked – it was just the RX acquiring the Sats. I have now resurrected my G3RUH box - seems to be behaving ok – got to do the ‘locked’ LED mod.
As an aside – do you know the input impedance at 10MHz for the Dieter LO unit please ?
Best regards de G8LBS.
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From: Neil Smith G4DBN
Sent: 21 March 2021 19:28
Subject: Re: [UKMicrowaves] 10 MHz Reference Distribution Amplifier
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.
On 21/03/2021 18:25, Colin Ranson wrote: