Re: internal vs. external ATU

[dw-4]

I am with Rick on this subject.
I also use the SG-230 in external config.
The thing I like about the 230 is its extended reactance ranges.
This comes in handy for multi-band antennas, especially where the Z @
frequency, is highly capacitive.
Internal ATUs are frequently size-constrained and are more suited to
loads which need a little tweaking.

Running the ATU externally with coax to the shack allows one to keep the
coax at 50 ohms unbalanced, which is what it is designed for, and
thereby minimize RF lost as heat within the coax.

I run ladder-line to the feed-point, and use a 1:1 balun rated to handle
high swr stress.
The SG-230 does require a continuous stand-by power of about 100mA while
in use.
It does not retain it settings when power is removed.
This may or may not be a concern in emergency (battery) operation.

The other cool utility of an external auto-ATU like the SG-230 is that
you can use it for experiments.
It takes about 2 seconds to find best match.
I love it for my experimental antennas!

Hope this helps,
N1BBR



------------------------------------------------------------------
Hello Chuck,

  That is my situation, and I opted for an external tuner.  I did that  
to avoid the loses that I would get from using 140 feet of buried coax  
to my dipole.  My antenna tuner is located at the other end of my  
coax, so my loses are minimized.  This involves using a remote,  
weather proof tuner.  I use an SGC model SG-230 remote tuner (coupler,  
according to SGC) and a multi conductor rotor cable for power and  
control.  The tuner is housed in a wooden box mounted on a 4"x 6"  
post.  The coax and rotor cable run through a buried  2" schedule 40  
conduit.  I have since changed the dipole for a 176 foot  inverted "L"  
antenna worked against ground radials.  I intend to add a 20 foot  
vertical for the higher frequencies, and an RF switch, also controlled  
with the rotor cable.  The SGC tuner has worked well and I am happy  
with the system.  I just think the 55 foot high inverted "L" is not  
optimum for 20 meters and above, thus the 20 foot vertical.  When I  
had the multi band dipole (doublet) I used 400 ohm window line from  
the tuner to the antenna.  This worked well, but I wanted to eliminate  
the window line.  I think the inverted "L" works as well and is  
bothered less by heavy winds.

73,

Rick Dettinger   K7MW
--
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[w8fn]

Say what? Both of mine do. After a power cycle, all the tuning relays
do come up in the open state, but a few dozen milliseconds of low
power RF at the desired operating frequency will restore the proper
matching condition almost instantly. As a matter of fact, one of the
annoying little quirks of the 230 is how very difficult it is to make
it "unremember" the setting for a particular frequency. Do you have
the "Tune From Memory" jumper in your tuner set to "NO" by any chance?

73...
Randy, W8FN

>The SG-230 does require a continuous stand-by power of about 100mA while
>in use.
>It does not retain it settings when power is removed.
>This may or may not be a concern in emergency (battery) operation.

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[David Cutter]

Duane

I would be interested to know more about your balun "rated to handle high
swr stress," please tell.
>
> I run ladder-line to the feed-point, and use a 1:1 balun rated to handle
> high swr stress.

When you are doing your experiments, what does the SG tell you?  I mean, is
there a way of determining the matching condition L and C ?  Or is it a go,
no-go test?

> The other cool utility of an external auto-ATU like the SG-230 is that
> you can use it for experiments.
> It takes about 2 seconds to find best match.
> I love it for my experimental antennas!
>
> Hope this helps,
> N1BBR


David
G3UNA

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