[1000mp] MP RFI Sensitivity

[Dan Kovatch]

Unlike the two cases mentioned here I have seen very little RFI to my MP . I
use a balanced center fed wire for 80-10 (including WARC bands) tuned with
an old vintage Johnson Matchbox (a true balanced tuner) running full
power -1500 watts- with little or no RFI in the shack. I also have an
inverted L for 160 and full size vertical on 80 -both with elevated radials
and notice no RFI from those. The monitor gets the 'wiggles' on some bands
but not enough to worry about. I have all manner of  connections to the MP
including serial computer cable, both keying lines (one to computer and one
to ouboard keyer) audio, amp relay and PTT to a W9XT card in the 'puter. I
had an old Heath tuner previous to this and 'smoked' a coax connector while
using it in balanced tuner mode. Maybe the current tuners with baluns are
part of the problem? They do not really act as balanced tuners but rely on
the balun to make the impedance workable. I believe this causes imbalance
and shack  induced RFI. The length of the line also dictates whether you
have a current or voltage node 'in the shack' My line length may be lucky
but I find no RFI to the MP on any band. Each setup is different but I think
it should be possible to use the mp if a truly 'balanced' situation is
maintained. I have not made any special grounding provisions other than for
safety (no counterpoise, radials etc)

FWIW
Dan W8CAR
----- Original Message -----
From: "Joe Giacobello, K2XX" <k2xx@swva.net>
To: <1000mp@mailman.qth.net>
Sent: Friday, March 07, 2003 2:42 PM
Subject: Re: [1000mp] MP RFI Sensitivity


> Steve, I've observed similar behavior (CPU reset) with my original MP
> when running high power into an end fed wire.  Even counterpoises and
> MFJ's Artificial Ground were only partially helpful.  My old TS-850 also
> was susceptible to RF getting into the audio section.
>
> 73, Joe
>
> Steve L. wrote:
>
> >I have a MP Mark V and under certain conditions it
> >will get a rough monitor tone (CW) but the output
> >signal is clean.
> >
> >When the monitor gets REALLY rough, the output signal
> >is also distorted/modulated/nasty.
> >
> >This happens when I use an off-center-fed antenna, fed
> >with 'balanced' feedline and RF is getting into the
> >shack via radiation. No grounding would ever affect
> >it.
> >
> >This is the only radio I've ever had that was RFI
> >sensitive. When QRO on 10m, I've had it reset the
> >rig's CPU suddenly. The thing has a ferrite clamp on
> >every I/O: key, RS232, headphone, linear relay, etc.
> >
> >I've since been forced to change my antennas due to
> >this problem. I use wire arrays with tall trees for
> >support.
> >
> >73, Steve N4SL Machias, WA
> >
> >
> >__________________________________________________
> >Do you Yahoo!?
> >Yahoo! Tax Center - forms, calculators, tips, more
> >http://taxes.yahoo.com/
> >_______________________________________________
> >List Moderator: Richard Lubash N1VXW
> >1000mp mailing list
> >1000mp@mailman.qth.net
> >To Change Options or Unsubscribe:
> >http://mailman.qth.net/mailman/listinfo/1000mp
> >
> >
> >
> >
>
>
> _______________________________________________
> List Moderator: Richard Lubash N1VXW
> 1000mp mailing list
> 1000mp@mailman.qth.net
> To Change Options or Unsubscribe:
> http://mailman.qth.net/mailman/listinfo/1000mp
>