Author Topic: Transmitting Audio Hum  (Read 5315 times)

VE7GTC

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Transmitting Audio Hum
« on: 2013-08-10, 02:58:55 »
Recently I have been told there is a fairly loud hum on my remote signal. If I do not use the remoterig but use the radio directly, the signal is clean. The hum is on all bands, HF through VHF. I have replaced virtually every part of the system (except the TS-2000) including a new remoterig system (both radio and control boxes) new cabling, power supplies, and microphone. Any suggestions appreciated.

gus  ve7gtc

dj0qn

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Re: Transmitting Audio Hum
« Reply #1 on: 2013-08-10, 12:38:45 »
Hi Gus,

Sorry to hear about your problem. I have fixed several cases of hum, there were
two possible causes:

1) The red strappings were not all fully in place. If one uses their fingers to set these,
it often happens that one or more does not make a clean contact. Once I switched to
holding the strapping with needle nose pliers at the edge of the insulation and pushing
gently down, then I never had a problem again. You may have covered this with your
rework activities, but I suggest you measure with a meter, or replace suspect strapping(s).

2) There is often a ground loop through the power supply. Make sure you use separate
power supplies on the radio side for the rig and RRC. Using the same one can cause a
hum problem.

If you already covered these two possible issues, then you found something new that I
haven't come across, so please keep us informed and good luck!

73,
Mitch DJ0QN / K7DX

VE7GTC

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Re: Transmitting Audio Hum
« Reply #2 on: 2013-08-11, 21:27:51 »
Thanks Mitch. This morning I sat down, opened all 4 boxes and went through the jumpers. Even though I had used needle nose pliers, there was at least 1 loose jumper in each box. The I got 2 separate regulated power supplies (I had been using one for both) and reconnected everything. Problem solved! Now to add the wireless board to the new unit. I may be back...

Thanks,   Gus   ve7gtc   k2gt