[R-390] Sigmapert Balun Review

[comcast]

I see many twinax baluns to RJ series outputs.  some of those even have 2 terminal screws on the body above the RJ connector.   Those are cheap too on ebay.  I wonder if those can be used soldering a bnc or uhf connector to the output with shielding

Jeff

Sent from my iPhone

> On Oct 20, 2019, at 8:10 AM, John Gedde <jgedde at optonline.net> wrote:
> 
> Out of curiosity, I bought a Sigmapert twinax to BNC balun from eBay.
> Sigmapert sells them on there from time to time and also offers them in
> twinax to UHF.  I had been using a Twinax to UHF connector adapter from Fair
> Radio to interface my 50 ohm coax to my R390 and R390A.  All that adapter
> does is tie one balanced terminal to the shield and feeds the signal into
> the other one.  
> 
> 
> 
> I wouldn't have expected much improvement with the Sigmapert, but I was very
> surprised at the huge reduction of noise I get using it!  I slight bit of
> signal strength reduction but the betterment of signal to noise is profound.
> I'm quite sure it has nothing to do with 50 ohms versus 125 ohms but rather
> the ability for the R390/A to reject common mode noise with a bona fide
> balanced input.
> 
> 
> 
> I haven't yet played around with adjusting the RF input stage balance
> adjustments, but it seems the whole common mode noise rejection thing is
> very real.
> 
> 
> 
> John
> 
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