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Old 02-05-2011, 13:33   #46
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Re: Attaching GTO15 Cable to Antenna Tuner

The theory is that the closer your antenna wire is to a grounded lower backstay, the more the signal can be coupled to ground. How much is actually coupled and how that affects your ability to communicate is another story. Iv'e done on-air testing and the party on the receiving end some several hundred miles away was unable to hear or see on his s-meter, any difference in signal whether the wire was directly against the backstay or held several feet away.

Eric
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Old 03-05-2011, 23:34   #47
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Re: Attaching GTO15 Cable to Antenna Tuner

I do not mean to hi-jack this thread but it seems to be working right around the issues I am trying to troubleshoot. I have a Kenwood 460 and a KT 1 kenwood external tuner. I have 4 inch copper strap run for the chainplate to the e plate about 12 feet away. The tuner is in a closet right next to the chainplate but then I have to run about 8 feet of wire to get up to the backstay insulator. I am using braid wire to conect all of the radio parts to the ground plane, The radio works pretty well but my Pactor II USB seems to hang up all of the time. I have ben told this is do to RFI. Should I put line filters between radio and tuner and tuner and backstay insulator? Should I also or instead of maybe get rid of the wire from the tuner and use a coax from tuner to backstay insulator and a Un Un at the insulator? Maybe that would help keep the RFI from getting back into the Pactor

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Old 04-05-2011, 07:12   #48
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Re: Attaching GTO15 Cable to Antenna Tuner

Do not swap out the GTO-15 for coax on the run to the backstay, and do not put choke filters on the GTO-15.

The SCS Pactor modems are designed to be quite resistant to RFI, but your rig's modulator input may not be. You may want to try putting some "mix 31" chokes on that modulator input that goes from the modem to the radio. It wouldn't hurt to put one on the coax coming from the tuner to the radio either, ideally one at the tuner and one shortly before the radio. If there is a control line from radio to tuner, put a filter choke or two on that also.

Ideally you should use a choke that you can wrap your cable through multiple times, because choke effect goes up with the square of the number of turns, or if you are using chokes just large enough for the cable to pass through, you may need several or more to do the job.

There are some good web resources for learning about RFI and chokes. Here is one:
The Proper Split Beads to Suppress RFI

You might want to try having the ground plane attached ONLY at the tuner, and not to the radio or other parts in the chain. This by itself might, or might not, clear up your problem.

Chip
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Old 04-05-2011, 08:23   #49
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Re: Attaching GTO15 Cable to Antenna Tuner

See also ➥ http://www.audiosystemsgroup.com/RFI-Ham.pdf
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Old 06-05-2011, 00:49   #50
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Re: Attaching GTO15 Cable to Antenna Tuner

Thanks Chip I will try detactching and re attaching different configs with regards to ground leads. Here in Palau I am stuck with what I can get my hands on but when we head over to Guam should be able to get most things if not they can be easily ordered. Figures the ferrites I bought are from Radio Shack! Mine is a Pactor ii SB and it seems to hang up the USB when receiving a signal it trips up the Modem ready signal goes false. It hapens about 95 percent of the time. When it dosn't happen the sstem works flawlessly.

Gord I had that download that is what got me thinking I might need a couple of Baluns and mabe one Un Un.

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