Close the window! ;-)
All I can think of is a quarter wave counterpoise connected to the
transceiver chassis and laid out on the floor of the shack.
Well, I can think of something else too. Add 2 to 4m (6 to 12 ft.) of coax
to the feedline. Common mode current is worst with a half wavelength of
coax and least with a quarter wave. If it is common mode current on the
line, and it happens to be at or near a max, that will reduce it
significantly.
However most likely you are correct that it is direct radiation into the
radio.
In that case you'll have to move the leg of the antenna.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Brian
Carling
Sent: Saturday, May 24, 2014 8:38 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Eagle problem?
I got problems with RF in the shack getting into equipment on 30 m. However
the inverted V I am using his right outside the window on one end and only
about 8 feet from the equipment. So I can hardly complain. In such cases
most of the remedies described here involving RF chokes etc. on the feedline
and other measures inside the shack will not make much difference. It's just
a case of too much RF too close by.
Best regards - Bry Carling
> On May 14, 2014, at 5:56 PM, Stuart Rohre <rohre@arlut.utexas.edu> wrote:
>
> Some Yaecomwoods do suffer from RF entering the rig.
>
> MOST ANY rig will if you have a bad shield connection on coax jumper, or
have rig too close to the antenna, (second floor shack), and there are many
other rig and feedline issues to rule out in any RFI case.
>
> Rule of thumb: Power all equipment from same circuit breaker of the
house. That ensures AC grounds will not be coming from widely different
locations. IF you have to use a long ground wire for lightning protection
ground on the station (like from second floor shack), consider that it could
act as an "antenna" for pick up of RF from the real antenna. You may need
tuned radials, or a radial for each favorite band.
>
> You could always examine the quality of the grounding of the mike cable
shield. Some older mike cords had just a multi-strand wire wrapped in one
direction and not a hatch pattern wire shield. Some aluminum foil shields
don't make a good low impedance connection by clamping. (Connections that
can't be soldered are suspect).
>
> You can do a step by step analysis of grounding, by starting at the mike
element and measure the resistance by ohm meter, of shield connection to
plug pin/ shell. Use a magnifier to examine connections on inside of radio
at mike. Check case to mike jack shell if that type.
>
> Some radios have a thru bolt to provide a "ground" terminal on back of
set. Make sure this bolt if present, grounds tightly to the chassis.
>
> Same could be said for any stud grounds on external tuner, etc.
>
> Good Luck, but usually a step by step exam of all connection points will
show up issues. Avoid feedlines that are odd multiples of a quarter
wavelength. Add 5 feet to a line to check for those types of issues.
>
> It used to be a common problem if the ring on mike connectors was not
fully tight on the mike jack. That is less of a problem, if the mike ground
carries through a mike pin.
>
> Let us know what you do to fix the problem.
>
> Stuart Rohre
> K5KVH
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