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Review of the LDG PRO-200 Autotuner

with 6 comments

The Revolution and the Evolution

So whats new in the shack? Whats new is an LDG AT-200 Pro Automatic Antenna Tuner. This is a thing of beauty. It makes the “problem” of tuning – not a problem at all. In fact, you don’t even have to think about it. Tuning and matching an antenna to the 50-Ohm impedance of your radio is now all automatic – not even a button push is needed.

So whats the revolution (or evolution)? Well, “tuning” is now done with microprocessors, thousands of memories, plus the usual hardware associated with switching LC circuits. Here’s how these things conspire to make it all automatic.

There is no longer the need to hit the “tune” button on your radio. Radios that use screwdriver type antennas need a RF kick to get them going. The RF kick of about 10 watts is enough to get the RF and SWR sense circuits up and running in a screwdriver to start the tune cycle. The same is true with a traditional radio with a built-in tuner. Hit the tune button and motors start whirling. They whirl trying different values of L and C to try to find a match. When the SWR is low enough, there you go.

If you are living in the middle ages, then you have an outboard tuner and you have to manually adjust combinations of inductance and capacitance with about 10 Watts out to find the match.

What is common in all these cases is that the tune cycle is not transparent and a continuous low power RF signal is required for tuning.

One up on a popular chicken roaster – “Set it, and forget it”

Did you ever hear the phrase “Set it and forget it? LDG has one over on chicken roasters. You don’t even need to set it – just forget it. Here’s the evolution.

The LDG AT-200Pro Automatic Antenna Tuner is capable of tuning while you are in QSO in SSB. In fully automatic mode, the tune cycle happens behind the scenes. There is no need to throw out a constant RF signal for tuning. The LDG can tune in SSB mode with varying RF output – just start talking. The LDG senses RF and SWR continuously and will adjust as needed.

The tune cycle starts behind the scenes when the SWR passes a threshold that you can set. So, if you are in QSO on 14.230 Mhz and move to 14.160 MHz the first word out of your mouth on 14.160 causes the the LDG to check the SWR. If it is past the threshold the tune cycle starts behind the scenes during your transmission. The same is true if you QSY to 28.4 MHz, 29.680/580 Mhz or to any frequency you choose.

The LDG is watching you and learning.

What contributes to the success of this is that the LDG has an internal frequency counter and 16,000 memories.

The memories store the tuning settings for frequencies on which you transmit. So, it learns and remembers. Its  gets even better, the 16,000 memories store frequency and tuning settings for up to 4 different antennas. 2,000 memories are allocated to each antenna.

To see this in action is quite cool. When the LDG is born (or you reset it), its a tabular rasa. – a blank tablet Choose a frequency on which to transmit. The LDG checks to see if that frequency (or a frequency close to where you are) is in memory (different frequency spacing for different bands).

If it is, and there is a stored tuning setting, then the LDG sets that almost instantly. If it cant find that frequency in memory it tries to find a LC match. When/if it does find a LC match then the frequency and tuning parameters are stored for next time. And so on, and so on, and so on. 16,000 memories; 8,000 for each of two ports; 2 antennas on each port. So, it’s basically, “Set it and forget it”.

The more you use the LDG the smarter is gets. The more it learns the frequencies that you use and more info it has on the LC settings needed to match your antenna(s).

Memories are non-volatile and so when you remove power it doesn”t forget. Will you fill up those 16,000 memories? Probably not.

More cool features

  1. Mobile mode. The LDG AT-2000Pro has an auto power up mode. Startup settings will turn the tuner on when it receives power. So put the tuner in the trunk and forget it. For non-mobile use the front panel push button to turn the tuner on and off. In off mode, its in bypass mode.
  2. Peak or average power out. The LED scale can read peak RF or average RF.
  3. Two power scales. 25W or 250W on the LED bar graph.
  4. Auto/Semi/Manual tune modes. Your choice. Default, LDG does it all.
  5. High/Low Impedance. Set depending on your antenna
  6. Manual LC settings. Allows one to “touch up” the tuning manually
  7. SWR threshold. You set what you think is a good match. From 1.1 to 3.5
  8. Antenna select. Select one of two ports on the back.
  9. Upgradeable. LDG will swap chips with you when they have new firmware. About $10.
  10. Bypass mode. The Power and SWR LED bar graph is operative but no LC is in circuit. #The LDG uses the two LED bar graphs (Power and SWR) to confirm your settings.

So whats the real deal?

There are some things that you should know about before you invest in one of these tuners.

  1. Imagine that you dropped a handful of ball bearings down your garbage disposal and then turned it on. Thats about what the LDG sounds like when it is tuning. The LDG AT-200Pro has heavy-duty physical relays to switch in and out the various combinations of L and C. The microprocessors switches these at a very rapid rate and its a sound that you need to experience to appreciate.
  2. The LED Power out resolution is not appropriate for 100W out rigs. The resolution is too large on a 250-Watt scale. Each LED is a larger increment. For example, the increment at 60W is 40W to get to the 100W LED. At the upper end, its a 50W increment from 200W to 250W. A minor nit but you wont be able to read power out to any reasonable level of percision over an analog meter.
  3. Some functions require you have a good sense of time. For example, to change among full tune cycle, memory tune cycle, and bypass … you need to press the tune key for … greater than 2.5 seconds … between .5 sec and 2.5 sec … and less than .5 sec. A minor complaint.
  4. Consider getting the LDG AT-100Pro. This is the 125 Watt version. It has fewer memories and a few less features but it is better suited for QRP and 100 Watt rigs. The price difference is $229 vs $199.
  5. This is probably not well suited for tube radios or solid-state radios that do not have SWR protection. It can take less than .5 seconds to tune on transmit if the frequency is in memory or it can take as long as 7 seconds of garbage disposal sounds to find a new LC match. During this time the radio sees high SWR. Most modern radios have power fold back to protect the final transistors. Tube radios do not have this and they may see very high SWR (worse than your antenna) as LDG tries to find a match.
  6. Were are not exactly getting the math on this nor how the tuner supports 4 separate antennas on 2 antenna ports. 16,000 memories; 4 antennas; 2,000 memories per antenna. How does that work? How does the LDG distinguish 2 antennas on the same port. This is an exercise left to the reader. If you “get it” let us know. It could be done with software if the antennas have way different SWR characteristics.


I  like it. I are using the LDG AT-200Pro with the Yaesu FT-847 and the ICOM 706-MKIIG – neither of which has a built-in tuner. My TS-950S and the TS-440S have the traditional motor driven tuner. The MFJ-949D manual tuner with a 300W built-in dummy load now services our three Kenwood Hybrid tube rigs – TS-520S/820S/830S.

At about $229 I think the AT-200Pro is a deal.


Written by frrl

August 3, 2008 at 5:18 am

6 Responses

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  1. Great review of the AT200Pro. I made the mistake of tuning with a bit too much power, and burned up R17, next to the two small potentiometers. Could you be so kind as to tell me the value of R17 since the schematic is unavailable to us mere mortals? Thanks in advance.

    Justin Reed

    March 27, 2011 at 7:59 pm

    • Like how much power? If you did not exceed the power handling capability of the tuner then this would indicate there is an engineering/design issue in the unit.


      March 28, 2011 at 3:06 am

      • Enough power that you can’t blame the failure on the unit. (100 watts on a radio that doesn’t fold back under high VSWR) I was hoping one of the photos in the review would be close enough for me to see the color bands of that resistor. Information is scarce and I was hoping somebody could pull the lid off and have a look at that resistor. I’m guessing this is the #1 failure mode of the tuner when too much power is applied, so this could be helpful to alot of people that don’t wish to send the unit back for a simple 20 cent repair.

        Justin Reed

        March 28, 2011 at 12:44 pm

      • For future reference, resistor R17 is 4.7K at 2W. Since I know somebody else will suffer the same fate!

        Justin Reed

        March 31, 2011 at 12:10 am

      • Thanks Justin, I’ve just started to repair of my 200Pro. (I’d forgotten I had it in cct even though it was on bypass and fired up my 30L-1 amp. Bang, flash!!)
        I’ve been after the value of R17 for ages. Thanks for the value of said resistor.
        I have also found a couple of surface mount diodes short cct and am replacing those. Hopefully the unit will start working again.
        Cheers, Rob G2BKZ


        June 7, 2012 at 10:22 am

  2. The AT200 Pro is the ideal automatic tuner for me. I just bought a Kenwood 480 HX, which transmits 200 watts, but does not include a tuner. I do a lot of mobile DXing and this is ideal for that and home use on a wire dipole.

    Dave Kaiser

    March 13, 2010 at 12:45 am

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