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Author Topic: remote ATU  (Read 1441 times)
9H1FQ
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Posts: 144




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« on: April 21, 2011, 09:19:09 AM »

I am looking to buy a decent external remote ATU, max 100 watts, which can tune anything, longwire, G5RV, dipoles, verticals etc.
Which is the ideal ?  MAC , CG,  MFJ,  SG,  LDG ?
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K5USF
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« Reply #1 on: April 21, 2011, 10:54:59 AM »

For 100 watts, I'd recommend the LDG Z-11pro2.  You can run it on AA batteries, it is cheap and it is small.  I used this for both a 31 and 43 foot vertical.  I put it in a electrical box from home depot.  It tuned my verticals from 80-6m - No problems. 73 de K5USF
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NA0AA
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« Reply #2 on: April 21, 2011, 07:03:43 PM »

The Z-11 would be a good choice for many applications listed.  And even with the cost of an enclosure added on, it's going to cost you less than an SGC.  I have an SG-230, which is a fine tuner and will handle 200 watts, but it's 2.5 times the cost of the LDG and it needs a LOT more power than that Z-11Pro.

BTW, you could remote power the LDG if you used DC power injection on the coax.

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VA7CPC
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« Reply #3 on: April 21, 2011, 11:16:07 PM »

I have a Z-11 Pro in my attic, tuning an attic-mounted fan dipole.  It runs on 8 "AA" batteries which last about a year.  Works fine. 

However:

It's designed for coax-fed antennas, and it won't tune _everything_.

If you want to tune _everything_, you might find that an SGC SG-237, or SG-230 (depending on your budget and needs) might have a wider matching range.

                   Charles
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M6GOM
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« Reply #4 on: April 22, 2011, 02:53:27 AM »

A used SGC230 can be found for as little as £100 in the UK. If you buy one that doesn't tune, 99% of the time its the IN4148 sensing diodes which have failed. They're tuppence and proper components not those SMD things so you can repair it yourself.
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AD5X
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« Reply #5 on: April 22, 2011, 05:19:20 AM »

Not sure that any tuner will tune "anything".  However, the SG-230 has the greatest matching range.  CG is not exactly truthful about their matching range.  MFJ has the lowest loss (though probably similar to LDG - I haven't used LDG).  The MFJ-927 and MFJ-926B have a neat feature (Sticky-Tune) that lets you force a re-tune and memory over-write on any frequency without affecting other saved frequencies/tuning solutions.

Phil - AD5X
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AA4PB
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« Reply #6 on: April 22, 2011, 05:42:54 AM »

Personally, I prefer the SGC tuners. My SGC230 has something similar to "sticky tune". If it tunes from memory on a particular frequency you can put it in bypass and then tune again on that same frequency, forcing it to do a full retune and load the new settings into memory for that frequency. Normally however this is not necessary because if it pulls the tuning solution from memory it then checks the SWR. If the SWR is over 1.5:1 then it automatically does a full retune and loads the new solution into memory for that frequency. This automatically handles the case were you have changed antennas since the last use of that frequency.

One thing I like is that, unlike some other tuners, it doesn't tune for minimum SWR or an SWR below some threshold. It tunes for zero reactance (resonance). It then checks to confirm that the SWR is below 1.5:1. Any time the SWR goes above 1.5:1 it automatically initiates a retune.
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WB6BYU
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« Reply #7 on: April 22, 2011, 08:53:39 AM »

Quote from: AA4PB
One thing I like is that, unlike some other tuners, it doesn't tune for minimum SWR or an SWR below some threshold. It tunes for zero reactance (resonance)...


Why would that make any difference?  Presuming you have a non-zero length of coax to your rig, it will still
see a reactive load in most cases when the SWR isn't 1 : 1, just as it would for any other load at that SWR.
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AD5X
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« Reply #8 on: April 22, 2011, 09:55:20 AM »

Personally, I prefer the SGC tuners. My SGC230 has something similar to "sticky tune". If it tunes from memory on a particular frequency you can put it in bypass and then tune again on that same frequency, forcing it to do a full retune and load the new settings into memory for that frequency.

Your SG230 works differently than the one I was using last year.  The SG230 manual says it will NOT retune if SWR is less than 2:1.  I found that it typically required more like a 3:1 SWR before retuning would occur if info was saved in memory.  And putting it in bypass first did not help.  As soon as it detected RF it would check memory and plug in the previously saved info.  If the SWR was less than the retune requirement (2:1 spec, but often more than this), it would not re-tune.  I wound up defeating memories (internal strap) to get around this problem.

Maybe I had a bad one.

Phil - AD5X
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AD6KA
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« Reply #9 on: April 22, 2011, 11:04:07 AM »

BTW, you could remote power the LDG if you used DC power injection on the coax.
Very good point. I wonder why more "Remote Tuners" don't
use this method, either built in, or as an option. The DC injection/recovery
circuits required are extremely simple and cheap.
Then again, so are AA batteries! Smiley

Good luck with your antenna project!
73, Ken  AD6KA
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