Good advice all. The problem with ef I had to battle with my ts480 (2nd
floor apt, floating rf ground), was the unshielded CAT5 cable that
connected the head unit to the main chassis.
I have zero rf problems with a newly acquired Jupiter. Of course I use a
common mode choke at the antenna, use a balanced antenna design and take
several other precautions.
Lee (NY6P)
On May 14, 2014 2:56 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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