Built in Antenna Tuner

[Celestialsailor]

Just wondering if anyone has installed a Ham Tx with a built in Antenna tuner on their boat. Such as a Kenwood TS-440SAT or Yaesu FT-890AT ?

[btrayfors]

Originally Posted by Celestialsailor

Just wondering if anyone has installed a Ham Tx with a built in Antenna tuner on their boat. Such as a Kenwood TS-440SAT or Yaesu FT-890AT ?

Yes, I have (a Yaesu FT900CAT). But I also have a SGC-230 tuner.

Be advised that built-in antenna tuners are for unbalanced (coax) feedlines and will not work with end-fed antennas like a backstay or whip UNLESS you add something like an UN-UN at the antenna feedpoint.

Bill
WA6CCA

[Celestialsailor]

Hi Bill...Thank for that. What is an Un-Un?

[Cheechako]

I've had the KW440 with built in tuner. It's not really adequate for TX. Also had a KW TS450 with external SGC tuner and it was great.
For money or space savings there are manual tuners out there and they are reasonable used. I have not used one though, I had one but eventually just sold it before I got a chance to use it.

[btrayfors]

Originally Posted by Celestialsailor

Hi Bill...Thank for that. What is an Un-Un?

It's an Unbalanced-to-Unbalanced matching transformer, sort of like a balun (which is for Balanced-to-Unbalanced applications).

See, e.g., www.balundesigns.com

Bill

[Celestialsailor]

Gotcha

[Goudurix]

Hi Celestialsailor,

even with a 1:4 UnUn or 1:9 UnUn these typical in-board tuners will have a hard time...they are usually meant to match not more than 1:3 VSWR's....

You might succeed chosing the total antenna wire length (from top op insulated backstay or wire until the UnUn) very carefully to avoid any very high impedances. In practice this means avoiding antenna lengths close to 1/2 or multiple of 1/2 wavelength for any target frequency.

You will have (very) good results if using cut-to-each frequency vertical wire dipoles as they will usually give about 2:1 VSWR's and these inboard-tuners can handle that well. But here you would need 1 dipole per target frequency. Not very handy, but probably the best antenna solution (efficiency-wise) solution on a sailing boat!

Jan
ON3ZTT

[W3GAC]

I've installed many ham transceivers on my sailboats, brothers's and other cruisers wherever we cruised. For the money, installation ease, ease of operation, and performance... you can't beat using what non-hams/ tech folks call a remote long wire 'spark plug' output tuner offered by many third party manufacturers (MFJ, LDG, SGC,...). Called sparkplug output tuners because their output is a single terminal (not a coax connector) often made of porcelain (or material that looks like porcelain with the profile that looks a bit like a spark plug. As stated by others, internal transceiver tuners do not have the matching range for the demands of marine antenna installations. The long wire tuners are specifically designed for our type of antennas (backstay & verticals that must cover a very wide range of operation frequencies. They have standard coax connector input which allows your shielded coax to run through the boat to the tuner location without picking up so much boat electronics RFI noise (more later). These remote single- ended tuners can then be mounted near (below deck) where the backstay or vertical is attached. FYI- everything thing attached to the single output terminal IS PART OF YOUR ANTENNA. So do not cable tie the lead in wire to a bundle of 12v, 120v, grounded, or sensor wires... most of your xmit energy will be coupled into those wires on xmit (maybe doing damage to other sensitive boat electronics and you will pickup a lot of boat electric hash/ rfi noise that will override weaker radio signals your trying to hear. Time after time when asked to help a boater complaining they never can hear wx/ marine nets I find they (or 'professional' installers have infact run their signal wire antenna feed right along such wire bundles! Even the coax between the rig and the remote tuner should try to be routed as far away from these other wiring bundles as practically possible because their still can be stray transmit RF on the outside of the coax shield and that also means it can also be picking up noise from the close wiring. The remote tuner can be get its 12v necessary to function right down the same input coax to ease the remote installation mounting/ powering options. It is VERY IMPORTANT for any tuner (and rig) to have the best RF ground you can give it. I emphasized RF ground because excellent RF grounds are short, minimal turns. Wide Copper strap material is best. Ham and better marine electronic shops, West Marine sell thin gauge Copper strap specifically fir this purpose. Lastly, I often find loose coax connections on boats. A modest turn using plyers is required (knuckle tight won't last). Then tape with good grade electrical tape to seal both the thread end and where the coax enters the connector if you made that connection to keep the every present marine moisture/ corrosive environment.

[Celestialsailor]

A lot of great information here...thank you so much. I was looking at aYaesu FT890AT (auto-tuner) but will strike that off the list. Maybe A Icom IC-718. Newer unit from Icom, cheap and very few bells and whistles. As long as has the option of Ham and General, I'll be happy.