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Reviews Categories | Antenna Tuners | LDG AT-600Pro Memory Autotuner Help

Reviews Summary for LDG AT-600Pro Memory Autotuner
LDG AT-600Pro Memory Autotuner Reviews: 35 Average rating: 4.0/5 MSRP: $359
Description: The LDG AT-600Pro Memory Autotuner is another great LDG product!
Product is in production.
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VK2FSTU Rating: 4/5 Jun 22, 2013 08:51 Send this review to a friend
A good tuner!  Time owned: more than 12 months
I wanted a tuner that would do the big Yaesu but only gave it a 4 because of it's difficulty in working compared to my LDG 100 which is much simpler and just works. This is a good unit, but the 100 walks all over it for simplicity and size.
KI4WMO Rating: 5/5 May 21, 2013 09:53 Send this review to a friend
Works great and as advertised  Time owned: 0 to 3 months
I bought one of the last new ones available at a substantial discount not too long ago (LDG has been transitioning to the AT-600Pro2 which has an attachment for an external analog-style meter).

Really, I have no complaints. I've owned the lower-power versions of this tuner from LDG before and had not problems with them. Every function on this works exactly as it says in the manual. I use it to tune up my vertical antenna from 80m-10m and it consistently brings the SWR down to 1, or occassionally 1.3. I have also used it on 160m from time to time, and it is satisfactory there as well (I don't normally bother because the feeline losses with my antenna are huge.

The wattmeter reads pretty accurtae and in line with my calibrated peak reading meter in peak mode, and seems pretty close in carrier. The meters and the corresponding circuits are a little susceptible to things like common-mode currents or RF in the shack (most similar units are too), but that isn't normally a problem in my station. However, if you have too much RF in the shack with this (and most other) autotuners, you can both confuse the microprocessors, and also cause a falsely high SWR reading and cause additional tuning problems. If your station, however, is well and properly grounded, I would not expect this to be an issue with these units.

I should also note that I consistently run this unit right up to 600 watts on a regular basis on SSB (and sometimes on CW) and it hasn't had any problems. Now, my worst incoming mismatch on 10-40m is only about 3.5 to 1, so that probably isn't stressing the tuner. However, on 80m, the incoming mismatch is a bit higher, however, the tuner has not shown any problems or failures there either.

I generally do not use this tuner on 6m, as I have a resonant yagi for that band. I have used it once or twice on the station's vertical to tune 6m though, and it did just fine.

I don't know what the differences are other than the meter attachment between this and the Pro2. The paper specs seem similar. I don't have two units to pop the covers off of an compare though, so I really can't say. Realistically though, either would do the job. However, remember when buying used tuners in this power range to be careful and if possible, inspect the inside of the tuner - it is not uncommon for folks to push a 600W tuner to 800W, which in some instances can create too much stress on the internal components. For those of you who are going into power over 100W or 200W for the first time, this is far less of an issue with used tuners in that power range. Therefore, when buying a high power-rated tuner, if you can't inspect a used unit (or wouldn't know what to look for) you may be safer just buying new. In that case, you'll have to go with a Pro2 at this point.

As a final word that most anyone who has read this far probably knows - remember that all this box does is adjust the incoming antenna impedance to something that your amplifier and/or solid state radio like to see better, in order to allow those components to pump out more power and to increase the life of those items. It does not increase the efficeincy of the antenna and feedline itself. Hence, you can still have substantial losses, in some systems, due to mismatches at the antenna or by the feedline. Remember that every 3db of losses cuts your power in half. If you run resonant antennas, this isn't really an issue - if you are concerned about losses, you can look up the spces for the feedline you are using and get a pretty good idea of your losses.

However, when considering a non-resonant system (untuned verticals, etc. - which is what I use), your coax losses can be more severe by a considerbale factor. In other words, if the true SWR at the antenna (and across your feedline) is 7:1, the tuner may tune it, but the vast majority of your power is simply being wasted as heat in your feedline (as the loss figures on coax ratings are only accurate at their design impedence of around 50 ohms). This also puts more stress on the tuner and your other antenna system components as well, and increases the chance for shack RF and common mode currents, etc. Therefore, when using in-shack tuners, you do need to be aware of what your "naked" or "true" SWR is for the antenna system without the tuner, and if it is high, use low loss-coax in appropriate lenghths which will considerably lessen the issue (you may also consider, if possible in your situation, other antennas for that band). There is a lot more detailed information about this on the web and this site. (note - you can reduce these losses by remote mounting a tuner at the base of such an antenna - I don't know how this would hold up there even in a weather proof box, but I know some folks have succesfully done it and I've considered it). This, incidentally, is also why many of us who run untuned verticals run so many radials - I know it won't increase my "gain" but it does help, to a point (and the returns do diminish after a certain average conductivity is reached as a result of the radials) with lowering the SWR and the mismatch. Indeed, if done carefully, you can lower the SWR considerably, even on the infamous 43' vertical. (NB - tuned antennas with traps or coils have losses in other ways - which is better is a subject of longstanding debate).

This last bit has been my long winded way of saying - even a good tuner such at this one won't help your signal get out if the antenna system is too far matched. It may make the rig and amplifier happy, but you still could be disappointed with the results if you haven't carefully reviewed, analyzed, tested, and optimized your antenna system for your given shack situation.

Have fun!
ZS4U Rating: 5/5 Sep 16, 2012 21:35 Send this review to a friend
Excellent Service  Time owned: 0 to 3 months
I purchased a second hand AT-600 Pro with about a month left on the warrentee. The previous owner only used 100W so he never had a problem. I use an AL-811H and tuned up with 350w when the ferrite cores started cracking and disintegrating. I sent it to LDG and within a week I received a brand new tuner that has been working flawlessly ever since! Now I am running 600W through the tuner into a G5RV junior with no problem - the tuner has some great features and will tune automatically if it senses a high SWR. Memory tuning is very quick. The relays during the tuning is noisy but works just fine.
WD8T Rating: 5/5 Aug 6, 2012 13:03 Send this review to a friend
Great tuner  Time owned: more than 12 months
Great tuner and it's been in operation for well over a year with an Ameritron AL-811 and OCFD antenna. I think it's a shame that some hams blame operator error or their own poor antenna/staton set up on a piece of equipment and then post a 1/5 review. Typical for eHam though.
KA3ZHX Rating: 4/5 May 16, 2012 22:34 Send this review to a friend
Pretty good tuner  Time owned: 0 to 3 months
The tuner itself is excellent, the manual is poorly written, the service response was excellent...There is alot of functionality in this tuner, it took me a little bit of time to figure out the UI, but once I got that dialed in, its been great
AI4HO Rating: 5/5 May 11, 2012 08:03 Send this review to a friend
Still a great tuner!  Time owned: more than 12 months
I have had my LDG AT-600Pro for about 18 months now, and have had nary a problem. I have since retired my G5RV and replaced it with a 40 meter double bazooka. This tuner goes great with my Ameritron ALS-600, as I only do 500-600 watts, even my 811H I only do 600, on a rough day..maybe 700 watts. This tuner goes great with the various 500-600 watt solid state amps on the market these days. Use some common sense and this tuner will do the job for ya. Are there some bad ones out there..of course..just like there have been bad batches of rigs on the market. Over all though..I find LDG to be a stand up company, I've been buying tuner from them for 9 almost 10 years now. Hopefully I'll be able to do another 10 or 20 years worth of business with em. See ya on the air!

73 de Mark

Formerly W3LZK
K6JEY Rating: 5/5 Mar 18, 2012 14:50 Send this review to a friend
With a KPA500  Time owned: 3 to 6 months
I have been using the AT600pro with an elecraft KPA500 and everything has been going fine. I use a beam and R7 vertical on 40-10m. I have the station well grounded. I preset the default antenna to Ant 2 and I have pre-tuned the tune to the typical places I operate. I put the amp in standby and put a bit of carrier through the tuner and it snaps in. (I have done pre tunes with the minimum SWR setting)I put the amp in operate and I am ready to go. Between the two units, I can change bands in a contest very quickly and ready to go in a very short time. Lots of hard hours at 500-600w and no problems.
PY2XB Rating: 1/5 Mar 6, 2012 11:44 Send this review to a friend
Design and quality issues. Terrible support  Time owned: more than 12 months
I am terrible sorry to write this bad review, but unfortunately my experience with this product and with the LDG support are quite poor.

I have bought an AT-600PRO unit to be able to use multiband antennas along with the Tokyo –Hy-Power HL-450B amplifier in DXpeditions. The THP HL-450B is a 400W class amplifier.
After tests in the home station I have used the antenna tuner in an IOTA expedition (August 2011) on a remote island in northern Brazil. The antenna was a center fed dipole using 450ohms ladder line with a 4:1 balun at the tuner side. Power applied to the tuner was around 400W.

*First problem*: one of the tuner’s toroids exploded after few minutes of operation. Then I have realized that some of the others toroids ran hot as well. I have returned home and checked on the internet. I verified that other people had the same issue (some made reviews here). I have contacted LDG and I was asked to return the unit. I have asked them to check my unit in order to verify toroids quality, but they do not have RMA tracking system to check on specifics of a returned unit. I doubt if any of my comments ad requirements were addressed.
I have returned the unit to the factory and I have received another one. Same toroids and assume that their quality is doubtful.

Anyway I decided to give it another try and wait to write the review after a second experience. I prepared two stations for an IOTA operation that took place on February 2012. The station that used the AT-600PRO had the same THP HL-450B and the antenna was a S9V43 coaxial fed Vertical with an UNUN at the base of the antenna. The second station ran 500W to a BigIR from SteppIR. The Antennas were mounted on salt water and they were about 45 feet one from another.

*Second problem*: When the 500W station transmitted, the AT-600PRO hooked to the S9v43 went mad (sometimes even barefoot we had the issue). The AT-600PRO was clearly picking up RF from the second station which was completely disturbing its operation. It started to tune up by itself and/or detuned completely. We have tried to decouple the RF by means of RF chokes and beads, but no luck. Again another operation spoiled by LDG.

Interesting is that we had an IT-100 LDG tuner (100W) that worked fine in the AT-600PRO’s place.

*Third Problem*: The LDG support is close to useless. In the second event, after explaining the case, I received an email stating that the problem with close by station is normal. They confirmed RF picked up. They also confirm that due the way it works, I would not see the problem with their LDG IT-100.
I intended to work along with them to find points in the circuit where RF could be decoupled. No way. I have also asked for the schematics so I could work myself on bypassing stray RF that may be making the microcontroller go crazy. No way.
Their suggestion was to use band filters in the output of the tuner. They send me a PDF of a 150W band-pass filter to be connected where we had 400-450W!

So, even though LDG firmware is very clever, my relation with this company ends here. Issue with products is not a problem. The way the company face the issues makes the difference. Unfortunately they face them very unprofessionally. The company is not oriented to fix and/or improve their products working closely with their customers. LDG seems to be a sale/replacement company.

Fred -PY2XB
KK8ZZ Rating: 5/5 Mar 5, 2012 20:35 Send this review to a friend
Follow up Review 18 months  Time owned: more than 12 months
Still tunes quickly, now assigned to a DX Engineering 43 foot vertical (great antenna!). I wonder if others who are having problems have bothered to GROUND their rigs and tuner to a good earth ground outside the shack? Guys, if it ain't well grounded, it ain't gonna work well for you !

(used this since the first review with Flex-3000, Icom PROIII, Yaesu FT-950, Icom IC-7200, Icom IC-7000, Yaesu FT-897D)

de KK8ZZ
W1NEJ Rating: 5/5 Feb 20, 2012 10:32 Send this review to a friend
A Nice Little Box  Time owned: 0 to 3 months
This is a great little tuner. I got it after I switched from an AL-1200 linear to my Elecraft KPA-500 solid state linear (another sweet little box).

It has worked very well to clean up what I would call minor SWR issues (not worse than 3:1 SWR at the band edges) of my two antennas, which were OK with the AL-1200 but I wanted to run the solid state amp with very low SWR.

But I cannot say that this tuner will work with any antenna or random length of wire. It is advertised to work with coax fed antennas, which should be more or less resonant to begin with.

The tuner has 16 relays, 7 of which switch capacitors to ground and 7 of which control the inductors to be in or out of the circuit.

The inductors are wired in series between the input connector and the antenna relay.

These are shunted by the 7 inductor relays. The relays are switched in a binary progression that starts with the lowest value of inductance, and works up to the highest value, and so on, in a binary progression, which gives 127 different values of inductance that can be switched in with a high degree of resolution since they are toroidal inductors that are wound with from 2 turns to many turns of wire, but I do not know the value of the inductors.

Each capacitance that is switched to ground is made up of 4 500 volt 5% mica capacitors connected in series. This gives each capacitor a 2000 volt rating, so don't worry about the comment that was made elsewhere that the capacitors are not big enough.

The combined values of each bank of 4 capacitors are 10, 20, 40, 80, 160, 320, and 640 pf. These are switched to ground by the 7 relays in a binary progression that starts with the lowest value, and works up to the highest value, and so on, in a binary progression, which gives 127 different values of capacitance that can be switched in with resolution to 10 pf.

Besides the 7 inductor relays and the 7 capacitor relays there are two additional relays. One of these is the hi/lo z relay. This relay switches the capacitors so they are connected to the input connector or the output connector so it is possible to tune antennas that are either more or less than 50 ohms, and antennas with either leading or lagging "j".

The last relay is the antenna relay that will switch the antenna tuner to two output connectors. Since I use a DX Engineering antenna switch located out doors to switch between my antennas, I use position one on the antenna tuner to feed the DX Engineering antenna switch, and position two to switch the antenna tuner to my dummy load.

The antenna tuner has not failed to find a match on my 40 meter OCF on 40, 20, 10, and 6 meters, and my 17 meter dipole. Of course, these are not difficult antennas to tune, and as stated I cannot vouch for this tuner using any other style of antenna or random length of wire. It tunes quickly, and the memory tune function works as advertised. When doing a full tune, you can hear those 14 relays clacking, but after it learns a frequency it is just a quick click of the appropriate relays.

LDG uses a very clever way to control and see what is going on in the tuner that once you play with a few times is very easy to learn. And you can press and hold the "function" button and then press the "tune" button to see the position of all the relays.

The tuner is in a nice metal box that has a good fit and finish, and the circuit board is very well made with mostly surface mount parts. This is not something that I would want to try and fix unless it was one of the wire lead components such as a coil or mica capacitor, which are installed through-hole on the circuit board.

As of this writing, I would recommend the AT-600 to anyone with a lower power linear, but be sure you do not exceed its power ratings if you use a continuous mode of transmission.
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