SGC Antenna Couplers

[Chris Muir]

Two questions:

1) Any comments on the relative merits of the SGC 237 versus the Icom AH4?

2) The SGC publication "Smartuners for Stealth Antennas" suggests feeding
balanced antennas such as non-resonant dipoles and small loops directly with
the inherently unbalanced output of their Smartuners. Would introduction of
a balun not be a good idea? Will baluns work ok in the very high SWR and
voltage situations which may be encountered? Will they still perform their
function in such circumstances? Are suitable baluns commercially available?

73,

Chris ZL1BOE

[W6RCecilA]

Chris Muir wrote:
> Would introduction of
> a balun not be a good idea? Will baluns work ok in the very high SWR and
> voltage situations which may be encountered? Will they still perform their
> function in such circumstances? Are suitable baluns commercially available?

Baluns are designed to work into resistive loads and do not handle reactance
very well. They also don't handle high resistive values very well. The SGC
doesn't have a coax connector on the output. I personally would not use
the SGC in a balanced configuration. The SGC ground is designed to be tied
to a vehicle body, ground plane, or counterpoise.
--
73, Cecil, W6RCA http://www.bigfoot.com/~w6rca

[frank jones]

Cecil, I have an SGC -230 and love it but use it for whips or single
wires. The manual advises against using it for balanced antennas such
as dipoles because, they say, that the tuner gets confused as to what
is counterpoise and what is antenna and can switch back and forth
between them... I've often wondered if it could be used with an
off-center fed dipole but haven't tried. The various configurations
shown to be usable include a loop, which sure would seem to present
the same problem as the dipole...

I have a faint recollection that SGC may have put a tuner on the
market that works with balanced lines, but not sure about this. I
also think that I have read that other suppliers may have done this,
but again am not sure. Maybe other readers have info on this.

73 FrankO N5MMB

[M0BQQ]

I have an SGC231 and feed an 135 foot dipole with it, the dipole is
ten meters above the tuner and is connected to the tuner with 450 Ohm
ladder line as suggested in the instruction book. I have also used it
with a 33ft vertical with 4 radials to good effect but the dipole by
far out performs the vertical with very good reports on all bands.

The manual says that it can be used with balanced antennas either at
the feed point or connected with balanced feeder between 300 and 600
Ohms impedence.

Jon

[frank jones]

Chris, I just downloaded the manual for the SGC 237 and saw two
things: One is that it is limited to 100 watts for ssb and ONLY 40
WATTS CW. So if you a brassbuster like me, you would be severely
disadvantaged. Another point, that you may already know, is that it
is designed to work with balanced lines (ladder line feed) or a random
wire or whip.

I was daydreaming about getting one to couple to a dipole via
ladderline and tune in any dang thing.... but I'd be limited to 40
little old watts.

73 FrankO N5MMB

"Chris Muir" <cm...@startrek.org.nz> wrote:

>Two questions:

>1) Any comments on the relative merits of the SGC 237 versus the Icom AH4?

>2) The SGC publication "Smartuners for Stealth Antennas" suggests feeding
>balanced antennas such as non-resonant dipoles and small loops directly with

>the inherently unbalanced output of their Smartuners. Would introduction of

>a balun not be a good idea? Will baluns work ok in the very high SWR and
>voltage situations which may be encountered? Will they still perform their
>function in such circumstances? Are suitable baluns commercially available?

>73,

>Chris ZL1BOE

[William Lee]

Have a look at the SGC SG-230. It is rated for 150 watts. The spec sheet
says 200 watts PEP so 100 watts CW should be no problem. Same as the 237 but
no 6 meter coverage.

William Lee N5WRX

frank jones <fjo...@ionet.net> wrote in message
news:7p7es0$lj1$1...@ionews.ionet.net...

[frank jones]

Jon, thank you very much for your information. I have the sg-230 and
when I first got it I called sgc and the tech told me the coupler was
not designed to handle balanced antennas, so I forgot about it.

I just got off the phone with sgc and they now tell me that I can feed
a dipole via ladderline, just as you describe. Which I think is
GREAT!

I was planning to put up a G5RV, but now am planning put up as long of
a dipole as I can and feed it with the sg 230. I can't quite make one
as long as yours, but can barely excede the 102 feet of the G5RV.

I live in Tulsa, OK, right smack in the middle of Tornado Alley, so
will have to take the sg 230 in during stormy wx. A friend lost his
sg 230 to lightning several years ago. He had nis permanently mounted
on his roof. argh.

Again, thanks for your input.

73 FrankO N5MMB

[frank jones]

Chris, I posted earlier that the sg 237 was not intended for more than
40 watts on CW,. I just got off the phone with SGC and they told me
that it was okay for code, that their specs used the term CW in its
true sense, that is continuous wave...key down all the time.

Also, both the sg 237 and the sg 230 can feed a balanced line, like
ladder line.

In reference to your query about using a balun, as a wild guess, I'd
think that you could use a balanced to unbalanced balun backward to go
from a co-ax feed to balanced and hence to the sg 237 or 230. MFJ
makes a balun intended to mount just outside your shack to convert
from ladderline to coax... maybe would be suitable. Again, just a WAG
(Wild A** Guess).

I'm sorry for having made the misstatement about the power limitation.