Close station to antenna distances will or can cause RFI problems. Under
close proximity conditions the RF field outside of the radio will be much
higher. Remember it is a inverse square law that applies here with regard
to RF fieldstrength.
Additionaly, the new breed of radios with all sorts of IN's and OUT's being
connected to various pieces of equipment, computers and such do provide
means for RF to be picked up on the interconnections and thus provide a path
for RF back into the radio. This is made more complex by radios with lots
of "broadband" circuits. I really think all manufacturers need to pay
increased attention to de-coupling every IN and OUT connector or port on the
new breed of radios.
One way to confirm RF getting into the radio from an external source is to
take a step by step approach disconnecting each cable and observe the
results. This is the basics of classes I taught several years ago:
"Troubleshooting by progressive isolation". Quite often one will find that
a single cable will be the culprit. In other cases it may be an additive
issue where more cables mean more RF.
Grounding is and is not an issue here. While one may have all of the
various pieces of equipment in the station bonded together and tied to a
single point with that point going to the station ground, remember that some
16 ft of ground length is 1/4 wave, or maximum voltage point, on 20M. Under
this condition the station is 1/4 wave above RF ground. Increasing the
ground length to 32 ft could reduce the RFI concerns for 20M. However, at
that point the stations is 1/4 wave above ground on 40M. My point here is
this, for operation on the highest frequency the ground should be much less
than 1/4 wavelength.
73
Bob, K4TAX
----- Original Message -----
From: "Mike Brown" <k9mi@sbcglobal.net>
To: <tentec@contesting.com>
Sent: Thursday, April 22, 2004 6:48 AM
Subject: Re: [TenTec] RFI and Orion Mic connector - bad info
> I've been reading a lot lately on the reflector about RFI
> problems with the newer Ten Tec rigs. I guess the
> burning question in my mind is, how close to the station,
> are the antennas? Having always lived on small lots,
> I've found this to be the problem, at least for me, in
> most RFI related problems. Just a thought.
>
> 73, Mike K9MI
>
>
> ----- Original Message -----
> From: "Bernard(wtrone)" <wtrone@comcast.net>
> To: <tentec@contesting.com>; <orion@tentec.com>
> Sent: Thursday, April 22, 2004 11:20 AM
> Subject: Re: [TenTec] RFI and Orion Mic connector - bad info
>
>
> > Duane:
> >
> > I also recently received a new Orion, but I too had
> read about
> > potential RF getting into the rig. I bought the hand held
> mike from TenTec
> > to help insure that I would not have the problem. I think
> that the wiring
> > may be a little tricky. There have been multiple posts on
> this reflector
> > about the wiring "problems." You might check the mike ground
> connections.
> >
> > I also have an Alpha and do not have the problem you
> describe, even
> > at full power output. I would also strongly suggest that you
> look at your
> > station ground system. All of your gear should be tied to a
> "common point"
> > ground with a lead length to the outside ground rod as short
> as possible.
> > You may also want to try multiple length of ground cable to
> your "common
> > point" ground rod if your problem continues.
> >
> > I really like the Orion, but it is a different type of
> rig and is
> > taking some getting used to!
> >
> > Good Luck.
> >
> > 73
> >
> >
> > Bernard, WA4OEJ
> >
> >
> > ----- Original Message -----
> > From: "Duane A Calvin" <ac5aa@juno.com>
> > To: <tentec@contesting.com>; <orion@tentec.com>
> > Sent: Wednesday, April 21, 2004 10:32 PM
> > Subject: [TenTec] RFI and Orion Mic connector - bad info
> >
> >
> > > I wrote the other day that the Orion I used a few months ago
> had no RFI
> > > problem with a standard Heil ProSet with the Heil-made
> Ten-Tec adapter.
> > > Well, I received my own Orion last night (yay!) and found
> that I must
> > > have a faulty memory (too much RF). I was chasing YA8G
> this evening on
> > > 20m CW, unsuccessfully, and decided to switch on the Alpha.
> Well, at
> > > only 500W out the lights on the front of the Orion were
> lighting up like
> > > a Christmas tree when the rig keyed. I found that if I
> pulled the Heil's
> > > microphone connector (which also carries the footswitch
> connector), the
> > > RFI went away. So it looks like I have some work to do on
> getting this
> > > straightened out. My apologies for the brain f*rt.
> > >
> > > On the other hand, other than a slightly "tight" encoder on
> the PBT/BW
> > > knob, the rig is a real joy. I'm still getting used to the
> controls
> > > again.
> > >
> > > 73, Duane
> > >
> > > --------------------------------------
> > > Duane Calvin, AC5AA
> > > Austin, Texas
> > >
> > > http://home.austin.rr.com/ac5aa
> > > _______________________________________________
> > > TenTec mailing list
> > > TenTec@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/tentec
> >
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
> _______________________________________________
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