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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