On 9/13/2011 5:39 PM, Jim Brown wrote:
> On 9/13/2011 7:16 AM, kc0hfl@cox.net wrote:
>> Current set up Radio Flex 5000 driving the 374A
> The problem is almost certainly at the Flex, and I'm guessing that the
> difference is the additional power of the larger amp.
I ran into something similar when pushing my DX-2sp to the legal limit
on 75 with the Yaesu FTDX5000MP.
It turned out to be RF coming back down the feedline to the tower. I
put a 5 core, 5 turn choke right where the coax reached the tower.
Absolutely no RFI since then.
73
Roger (K8RI)
>
> Assume a Pin One problem at the Flex, and add multi-turn ferrite chokes
> to audio lines (mic, processing) and any other lines that plug into the
> radio. Study http://audiosystemsgroup.com/RFI-Ham.pdf
>
> There's another mechanism that SOUNDS like RFI, but is NOT. W8JI
> alerted me to it, and I've duplicated it in my station. It happens when
> you have a 12V rig with V- bonded to the chassis of a power supply, and
> audio accessories that feed the radio powered from that 12V supply.
> What happens is that varying DC current with modulation causes
> modulation of the V- line by the IR drop, and that modulation is added
> to the audio. It SOUNDS just like SSB detected by an AM detector, so you
> think it's RF feedback
>
> 73, Jim Brown K9YC
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|