Agreed, that is a tough RF environment. The use of a common mode choke on
the feedline, be sure every piece of equipment is securely bonded to a
common point, making sure all PL-259's are very tight not just finger tight,
and us good quality coax {high % of shield} is about the best one can hope
for.
Although I understand from our earlier discussions, space and position for
antenna's at your QTH is an issue. Thus more separation between antennas
and radios is desireable to help your issue. Just may not be possible. Not
recalling your antenna configuration, perhaps changing antenna length will
change the voltage point issue relating to 30M. This of course might make
other bands difficult to match.
73
Bob, K4TAX
----- Original Message -----
From: "Brian Carling" <bcarling@cfl.rr.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, May 24, 2014 1:37 PM
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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