Auto Antenna Tuners: Worth it?

[N5HMX]

I run QRP to 100 watt power levels - and am in the market for a new antenna tuner. Noticed that some of the new automatic antenna tuners are priced in the same neighborhood of many manual tuners.

I've never seen one of the automatic tuners...some are advertised as being small - seems that their tuning caps and coil would be much smaller than what would be expected in a manual tuner, and this leads me to believe that they could be troublesome.

Am I wrong?

I'll be using ladder-line to a 1/4 wave at 160 mts for general "all-band" operation, so I'll have to add a balun.

[G4ALA]

The weather proof CG 3000 auto tuner, which I run, takes 300 Watts. As far as I can tell, it is equivalent to, if not the same as, the MFJ version.

In its instructions it warns against putting a balun on its output. It's input is strictly coax.

I cannot speak for other tuners. Try down loading a few manuals at

www.mfjenterprises.com

to see if you an find any of them that has or accepts an output balun.

73

John
G4ALA

[WB2UAQ]

A manual transmatch is pretty easy to build so I have always gone that route.

The automatic ones might not have the impedance matching range. Maybe some one can supply us with their typcial range (10 to 2000 at what Q, etc).

I wonder how some of them will hold up to high voltages and high circulating currents when the impedance is at the extremes.

I also wonder how a mfr determines the power rating. I have experienced arcing at some pretty low power levels.

Have fun and 73, Pete

[K4AX]

I use a external auto tuner, a MFJ-993B, and I love it, once you tune up on a band, and go back to the same frequency, it will tune instantly. The LDG auto tuners do the same.

My tuner does have a 4:1 balun internally for balance line, which works just fine the few times I have tried it. It also has a freq counter that tells you the last frequency you tuned up on, and shows capacitance and reactance.

The LDG tuners are very popular, the AT100 and 200 are pretty common and work great.

[WE6Z]

I think an auto tuner is worth it. I use a LDG AT100pro and I love it. It tunes my G5RV and 10 meter antennas anywhere I want to go. It saves a heck of a lot of time, especially during contest when changing bands every 5 minutes. I originally had a MFJ949 manual tuner.

[KA4DPO]

There are pros and cons for both. A manual tuner gives you more flexibility than an auto tuner while an auto tuner provides convenience.

If you are thinking about an auto tuner I would only consider the SGC or Icom AH4 since these have a very wide impedance range and will match nearly anything that a good manual tuner will.

Unless you are going to mount an auto tuner directly at the feedpoint of an antenna then a good manual tuner is a much better choice for a variety of reasons.

[W4GLM]

Jerry, I use a similar approach that you are describing.

I use an Icom AH-4 auto tuner mounted in a plastic

garbage can to keep the tuner out of the

weather.

It transitions to

about 25' of commercial window 450 OHM line to a loop

antenna 1000' long up about 30' - 35'.

Without a doubt it works all bands using one side of the

window line to the antenna side of the AH-4 and the

other side of the antenna to the ground lug. tunes

quickly and works all bands 160 - 6.

[M3KXZ]

I can vouch for the SGC 237 - it certainly seems to be able to match anything with no trouble at all. I move around a lot on a band and also between bands with the same wire antenna, and this just makes it so quick and easy. This particular one handles 100W and only requires 3W to tune (although I've had it tune with just a couple of watts)

When going light /p then I use an Elecraft T1 - again fantastic and seems to match most things I throw at it - along with a 4:1 balun if needed. Can only handle 25W (though I know people have tested it at higher)

[M3KXZ]

I only place the SGC237 directly at the feedpoint when /p. At home I use twin lead between the antenna and the tune - which kind of means I'm still attaching it at the feedpoint as the feedpoint is now the tuner end of the twin lead.

[KA4DPO]

Jerry, I use a similar approach that you are describing.

I use an Icom AH-4 auto tuner mounted in a plastic

garbage can to keep the tuner out of the

weather.

It transitions to

about 25' of commercial window 450 OHM line to a loop

antenna 1000' long up about 30' - 35'.

Without a doubt it works all bands using one side of the

window line to the antenna side of the AH-4 and the

other side of the antenna to the ground lug. tunes

quickly and works all bands 160 - 6.

How well does that loop work? There are EXPERTS here on the ZED with 5 or 10 years of experience who seem to think that a loop the size of yours can't possibly work because the signal will be chock full of DEEP NULLS.

My guess is that at 35 feet the pattern is pretty symetrical and I bet it works like a champ. Gee, you think the experts could be wrong?