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Author Topic: RF Problem  (Read 395 times)
KA5TIW
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Posts: 1




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« on: July 09, 2005, 05:18:50 PM »

Have started up in Ham Radio again and hooked up my Kenwood TS140 in my home.  Using a trolling motor battery for power supply as I had sold my regular power supply when I went inactive.

Having a problem on 10 and 15m.... when I key mike on SSB have "squeal" that drives my transmit to 100w. out. It is an RF loop ... pretty sure of that but don't know where it is coming from.  Have a ground wire going outside to a grounding rod driven into the earth and think I have everything grounded ok.

Any suggestions appreciated,

Jim
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WB2WIK
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Posts: 20666




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« Reply #1 on: July 11, 2005, 08:33:42 AM »

What you need, if you need a ground to resolve this, is an actual "RF ground," which on the higher HF bands cannot be achieved using a wire to a ground rod.

However, the problem may be one of antenna radiation re-entering the rig via the mike cord or other stuff, in which case grounding the rig probably wouldn't help anyway.  You need to isolate the rig from the antenna, if this is the problem, and the easiest way to do that is to move the antenna farther away from the radio.

You didn't say what kind of antenna you have, or how close by it is, but if the antenna isn't balanced, or is closer then about fifty feet from the TS-140S, this could easily cause a problem.

Another possible issue is the battery power source.  The TS-140S, like most HF rigs, weren't really designed for 12Vdc operation; they were designed for 13.8-14.2Vdc operation, which is the normal "running" voltage in an automotive vehicle and is also the voltage provided by regulated power supplies when adjusted for powering "mobile equipment."  Many rigs, including my Kenwood, don't do well at 12.0 Volts, which is the battery voltage, and do much worse if this voltage sags below 12 volts (like down to 11.8 or 11.7 -- my TS-850S stops working altogether at about 11.6).  I've seen "howling and squealing" caused by nothing other than inadequate operating voltage.

WB2WIK/6
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K5YM
Member

Posts: 4




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« Reply #2 on: July 14, 2005, 01:48:12 PM »

Not that familiar with that radio, but check to make sure you don't have the carrier level control cranked up causing a carrier on SSB when mic is keyed. Its used mainly for AM and CW so none or very little carrier is needed.
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