Attaching GTO15 Cable to Antenna Tuner

[SoonerSailor]

The tuner in your Kenwood will only match an SWR up to 3:1 (I'm pretty sure). This isn't a wide enough range to reliably match your backstay antenna to your radio.

To do that job you should employ something like the Icom AT-140, SGC-230, or even an MFJ-927 located near the base of your backstay. You would run coax to the tuner, and the tuner antenna output to the backstay with GTO-15, with an RF ground also attached to the tuner.

Thats the short story anyway.

[hooligan6a]

SoonerSailor, Thanks for the info but I mean how do I physically connect the GTO-15 to the radio, what type of connector do you use.

[btrayfors]

You don't.

The least expensive and best way to use your radio with an internal tuner (which is intended for use with unbalanced coax cable, not GTO-15) is to use an UN-UN near the base of the backstay antenna, then connect that to the radio using any convenient length of 50-ohm coax (RG-8X, RG-213, etc.).

The purpose of the UN-UN is to transform impedences at the base of the backstay antenna (which is, for all intents, just a random-length end-fed wire antenna) into those which the tuner in the radio can handle.

A good UN-UN will cost about $80 and it's well worth it. Those made by Balun Designs (Balun Designs Home Page) for end-fed wires are particularly good.

Bill
WA6CCA

[hooligan6a]

btrayfors, They have several un-un, should I use the, 50 to 32ohms 100 to 50ohms or 25 to 50 ohms Thanks for your help, this is all new to me.

[btrayfors]

Originally Posted by hooligan6a

btrayfors, They have several un-un, should I use the, 50 to 32ohms 100 to 50ohms or 25 to 50 ohms Thanks for your help, this is all new to me.

They make one which is especially for use with end-fed vertical wire antennas. They've changed the model numbers since I bought mine. Suggest you call them or email them for a recommendation. Tell them what you're planning to do.

You will, of course, need some sort of RF ground. Lots of options, including:

- copper strap from UN-UN to nearest bronze thru-hull;
- tuned or untuned radials from the UN-UN, using any type insulated wire;
- aluminum toerails, lifeline complex, etc.

One easy way to do it is to use the KISS-SSB radial ground system...very simple to install and works quite well. Widely advertised in mags and on eBay.

Bill

[hooligan6a]

Thank you, I plan to use the Kiss-ssb.

[osirissail]

Originally Posted by hooligan6a

I am confused. I want to install a back stay antenna to my Kenwood 460, with a built in Antenna tuner. What kind of connector do I use to attach the GTO-15 to the radio?

You do connect the GTO-15 to the "radio" - it is connected to an insulated terminal post on the "Tuner". This is a separate box that contains electronics that will match the impedance of your backstay wire to the selected transmission frequency on your radio.
- - If you do not have a "Tuner" then you need to consult a good SSB/HF technician for advice on which "Tuner" will work with your make/model SSB/HF radio.

[btrayfors]

Originally Posted by osirissail

You do connect the GTO-15 to the "radio" - it is connected to an insulated terminal post on the "Tuner". This is a separate box that contains electronics that will match the impedance of your backstay wire to the selected transmission frequency on your radio.
- - If you do not have a "Tuner" then you need to consult a good SSB/HF technician for advice on which "Tuner" will work with your make/model SSB/HF radio.

I think you missed the OP's question: he wants to connect the backstay antenna to his radio which has an internal antenna tuner.

You could, of course, use an external tuner...a good marine one will cost $500. Or, you could use the internal tuner in the radio, together with an $80 UN-UN as outlined above.

Bill

[osirissail]

Aha said the blind man, now I see - - But the radio with an internal tuner should have a "terminal post" some where on it that is obviously for the "single wire, non-shielded" GTO-15. If there is only a "coax" terminal then something is very strange or unusual. Maybe there is some confusion as the "radio" actually sends the "tuning command" to the "tuner" and displays the "Tune" message on its display head even though the actual tuning is done by the separate box.

[btrayfors]

Originally Posted by osirissail

Aha said the blind man, now I see - - But the radio with an internal tuner should have a "terminal post" some where on it that is obviously for the "single wire, non-shielded" GTO-15. If there is only a "coax" terminal then something is very strange or unusual. Maybe there is some confusion as the "radio" actually sends the "tuning command" to the "tuner" and displays the "Tune" message on its display head even though the actual tuning is done by the separate box.

No, there's no provision for a single-wire antenna. Remember, this is a HAM RADIO (see post #16). The internal tuner -- completely internal -- is intended for use with coax-fed antennas only (like dipoles, yagis, etc.). If you want to use a random-length end-fed antenna (like a backstay), then you need some sort of balun . This is very common in the world of ham radio.

Bill
WA6CCA

[hooligan6a]

Btrayfors, You are right, there is no single wire, terminal post. only a coax type terminal. I guess I can run a coax from the tuner to the UN-UN and then connect the backstay to the UN-UN. Would that be right? Don't know what balun is.

[btrayfors]

Originally Posted by hooligan6a

Btrayfors, You are right, there is no single wire, terminal post. only a coax type terminal. I guess I can run a coax from the tuner to the UN-UN and then connect the backstay to the UN-UN. Would that be right? Don't know what balun is.

Yes. An Un-Un (unbalanced-to-unbalanced) is a type of balun (balanced-to-unbalanced).

The UN-UN has two studs and one coax connector. The SO-239 coax connector is to connect the coax feedline from the radio to the UN-UN.

One of the studs is for the antenna (GTO-15 connection to the backstay antenna). The other is for the RF ground (KISS-SSB in your case).

Very simple, neat, robust, and effective. Also, quite economical ($80) compared to the cost of an automatic tuner suitable for marine use ($500).

Bill

[hooligan6a]

Bill, thank you so much. You saved me a bunch of $$$

[SoonerSailor]

Keep in mind your inboard tuner may not be able to get an adequate match on some bands even with the un-un in place. With the right one, you should be able to get a match on at least one band of interest and probably more.

[Sheriff]

Originally Posted by btrayfors

No, there's no provision for a single-wire antenna. Remember, this is a HAM RADIO (see post #16). The internal tuner -- completely internal -- is intended for use with coax-fed antennas only (like dipoles, yagis, etc.). If you want to use a random-length end-fed antenna (like a backstay), then you need some sort of balun . This is very common in the world of ham radio.

Bill
WA6CCA

or an external amateur tuner would do the trick