Feeding a Multi Band Dipole With an Ah4 Icom Tuner

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Paul Nix

I'm thinking that it would be convenient to have my AH-4 outside near the center support of my inv-V antenna which has a balanced feedline (and then I could run coax into the house instead of the current situation where I have a run of balanced feedline up in the attic supported with pieces of fishing line to keep the feedline from touching anything).

I bought a Palstar 4:1 balun some time ago and am wondering how successful it would be to modify the output of the AH-4 so that it has an SO-239 coax connector so I could then connect to the balun using a very short length of coax ?

Does anybody have experience doing this ?

- Paul, WB5AGF

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You don't need the balun. Just connect the ladder line to the two output terminals. Don't ground the tuner. Where the coax enters the house make a choke out of several turns of coax then ground the coax before it goes into the house.

The balun will not improve performance. Also note that most baluns are sensitive to impedance so that using one on the output of the tuner is not a great idea because you are expecting the antenna's impedance to be all over the place.

The tuner is quite happy floating above RF ground.

73,
Chris, K9EQ

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On Mon, Oct 26, 2020 at 08:17 PM, Christopher Petersen wrote:

You don't need the balun. Just connect the ladder line to the two output terminals. Don't ground the tuner. Where the coax enters the house make a choke out of several turns of coax then ground the coax before it goes into the house. - 73, Chris, K9EQ

Chris is correct. I've run dipoles, off-center dipoles and loops using the method Chris describes. Depending on the coax, check the Interweb for the correct amount of turns & diameter to create your current balun.
- 73,
Jeff/wb0m

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Paul Nix

(Chris & Jeff)

Thanks guys for the responses.

I've wondered about that (letting the AH-4 'float ' above RF ground) but then that necessitated that I also consider how to configure an RF break in the power/control wiring - wrap them around-and-around some ferrite cores I suppose. (In my mind's eye I'm seeing a picture of how tower lights' power wiring was isolated where it went from the ground up onto a hot AM broadcast tower.)

- Paul, WB5AGF

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BTW:  The tuner is grounded through the coax, whether it's at the radio or going through a bulkhead or lightning suppresser. More can't hurt nor can simple, coiled-coax chokes.

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73,

Jeff/wb0m

toggle quoted messageShow quoted text

(Chris & Jeff)

Thanks guys for the responses.

I've wondered about that (letting the AH-4 ' float ' above RF ground) but then that necessitated that I also consider how to configure an RF break in the power/control wiring - wrap them around-and-around some ferrite cores I suppose. (In my mind's eye I'm seeing a picture of how tower lights' power wiring was isolated where it went from the ground up onto a hot AM broadcast tower.)

- Paul, WB5AGF

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Richard Rohrer <kc3ef@...>

I agree, I use my AH-4 to feed a 120 ft dipole feed with about 39 ft of 450 ohm line.  It will tune all bands between 160 and 6.  Not very efficient on 160 or 6, but I have made contacts over 1200 miles on 160.

73
Dick - KC3EF

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But common mode choke s with 2 of 140-43 or 240-43 cores in both, the coax AND the control cabel can! Well above 30 db at 80 m und more above.

gl es 73

Hermann
aa6hs

Am 28.10.2020 um 01:44 schrieb wb0m:

toggle quoted messageShow quoted text

BTW:  The tuner is grounded through the coax, whether it's at the radio or going through a bulkhead or lightning suppresser. More can't hurt nor can simple, coiled-coax chokes.

-

73,

Jeff/wb0m

(Chris & Jeff)

Thanks guys for the responses.

I've wondered about that (letting the AH-4 ' float ' above RF ground) but then that necessitated that I also consider how to configure an RF break in the power/control wiring - wrap them around-and-around some ferrite cores I suppose. (In my mind's eye I'm seeing a picture of how tower lights' power wiring was isolated where it went from the ground up onto a hot AM broadcast tower.)

- Paul, WB5AGF

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Richard Rohrer <kc3ef@...>

Hi Bob,

The molex number is 76650-0059 with 0.093 pins.  I have added the molex cut sheet for it.  If you can't find locally and don't need it right away let me know, I am going out of town for a week.  I think I have a couple in the connect junk box.  I changed one of my AH-4 to a 4-pin industrial connector along with a SO239 for portable use.

I have never used chokes on either the control line or the coax and have never had any problems.  The unit at the house is about 30 ft from the entry panel.  The portable unit I have 50 ft of control cable and 50 feet of coax and have not had any problems with either.  Knock on wood.

73
Dick - KC3EF

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Source: https://groups.io/g/IcomTuner/topic/anyone_using_the_ah_4_to_feed/77830174?p=

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