Author Topic: 1216H generates ~10kHz wide interference on 17m  (Read 686 times)

W4AFK

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1216H generates ~10kHz wide interference on 17m
« on: 2020-12-21, 20:48:30 »
We have a 1216H and 1216L at our remote site and control a rotator. I've had these for many years and finally decided to put them to use as originally planned.

First: It does work, and we can remotely control the rotator.

The challenge: What we noticed was that the 1216H (or L) generates very strong interference over ~10kHz 17m and on other bands. The interference changes center frequency when you rotate the antenna and also drifts by itself. The 1216H is connected to the same PSU as the radio.

For what follows, please see the attached drawing

Tried with 1 "GND", 3 "+" and 7 "-"

We know it's "radiated" as if we select an antenna that is on the other side of the garage, the "interference" drops a lot.

The problem definitely appears to come from the connection to the indicator pot (3 and 7). If we run up the webswitch and relay card with no cables attached there is no interference.

Any ideas ?


« Last Edit: 2020-12-28, 23:31:13 by W4AFK »

W4AFK

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Re: 1216H generates ~10kHz wide interference on 17m
« Reply #1 on: 2021-02-25, 05:33:26 »
Solved ... We had an older version of the "1216L" and followed Mikael's instructions to solder a 100nF capacitor between two ground planes. Result: The RF noise is gone  :)