[CQ-Contest] 2-Radio Interference Question

Tom Rauch W8JI at contesting.com
Wed Dec 27 17:39:38 EST 2000

> When testing at 125w output, R2 never hears any phase noise
> when R1 is transmitting. R1 always hears phase noise when R2
> is transmitting. 
> This is very consistent with any combination of antennas
> and/or directions, as expected the noise level is greatest
> when the antennas are pointed at each other, and least when
> going away from themselves.
> The appropriate application of stubs are effective, but it
> is curious to me that there isn't similar noise going both
> ways.

Every radio is different! I keep whining about FT1000MP's because 
some are prime examples of this effect.

While many I tested are the same as my rig, some are 20 dB or 
more worse! The bad rigs just murder a weak signal even 5 kHz 
away when they are 500 miles or more away.

Maybe there is a variation in your rigs.

I suspect, however, that you may have a transmitter noise problem 
not related to the synthesizer. Most likely if it is in the synthesizer 
it would bother the receiver as well as the transmitter. You may 
have one rig with TX noise from something that is not common to 
the receiver, either an oscillator ..mixer... or amplifier stage or 
related components.    

> I seems that there might be a problem with R2, or the
> plumbing on that station that needs fixing. I'm going to
> play with the plumbing to see if it tells any stories.

I'd lean towards the transmitter having noise on the radio that is 
quiet on the receiver.

73, Tom W8JI
w8ji at contesting.com

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