Review of the Palstar AT2KD Tuner

Palstar AT2KD Tuner

This review of the Palstar AT2KD tuner will start off with a few comments about tuners in general, and will not get too technical.  There are many other places to find technical reviews of this device…  eHam ratings indicate that it is a 4.8 out of 5, which is a pretty darn good rating, and some pretty good technical reviews there as well.

Over time I have had both auto tuners, and manual tuners.  I have used differential tuners, and standard tuners…  I always return to manual tuners, using roller inductors, and large caps every time…  An auto tuner is simpler to operate, but the power levels just are not there yet for me on anything I can afford, nor have I been able to get an autotuner, (of the ones I have used), to tune to an exact 1:1, every time, on every band.  It is always something like 1.x:1, I have seen as high as 1.7:1, which can cause issues with the new solid state amps, such as the ALS-1306, which I own.  See the section under “Conclusions”, for more on that subject.

I now operate RTTY at 750 Watts, which is 100% duty cycle.  I know of no autotuner that will take that kind of beating which I choose to afford, however the Palstar AT2KD, (manual tuner), will, and does, and I am willing to afford it…  Most of the time I down-rate it to 500 watts, but when I need it, I can run 1 KW on CW, or 750 watts on RTTY.  Why?  Because it is a tuner built like the old days, big caps, and a bigger coil inside.  Honestly, this thing is built like a tank.  See this link for Palstar’s video on the tuner.

Here is what Palstar says about the tuner:

The Palstar AT2KD antenna tuner covers 6 to 160 Meters with a power rating of up
to 2000 watts PEP and is identical in all respects to the AT2K except
instead of three controls, the tuner features just two to tune your antenna.  
The AT2KD matches dipoles, center fed doublets, Verticals, end-fed wire, 
delta loops, beams, Windoms, Inverted V's and an optional external 4:1 or 1:1 
current balun for balanced wire feeders can be purchased during check-out.
Featuring a 6 position antenna selector switch, the AT2KD offers forward 
power metering in two ranges, 300 and 3000 watts.

So why did I purchase a differential type of tuner, as opposed to a normal type of tuner, or higher power autotuner?  Power handling capability, SWR issues with a new amp, and the cost.  I am just not able to afford $1595 for a new, or $1200 to $1300 used on a Palstar auto-tuner that would handle 100% duty cycle full power, so the Palstar manual tuner was ordered.  I dislike running anything at the edge of it’s limits, and any autotuner I could afford would be at the upper limits of power.  So I reluctantly made the decision to return to manual tuners.  I was replacing an autotuner which could handle 750 watts of CW, 1000 watts of SSB, but only 500 watts of RTTY, and still be at the very top of its power ratings.  My Ameritron ALS-1306, is a solid state amp, and as such, is very, very, sensitive to SWR mismatches, much more than any tube amp ever thought about being.  See my review of the ALS-1306 here.  The ALS-1306 demands as close to a 1:1 SWR as you can get, else it faults, or worse kills the final stack.  An autotuner never quite gets to 1:1, so I sometimes had faults.  In some cases my old autotuner would leave me at 1.5, or 1.7 to 1, while this was OK with my old AL-82 tube amp, (see review here), the new solid state ALS-1306 would fault every time, and then I would end up manually tuning the autotuner anyway.  Given the penchant the ALS-1306 seems to have for killing finals when mistuned, and the fact I was manually tuning my autotuner every time anyway, I came to the conclusion I needed to get a manual tuner that could take more power, and give me 1:1 matches.  Hence the desire to change tuners…

I began looking at manual tuners.  Palstar immediately came to mind, so I looked at the AT2K, and the AT2KD.  The difference is that the AT2K is a standard tuner, with three controls, input, output, and induction, while the AT2KD is a differential tuner, with only two controls, capacitance, and inductance.  The input and output caps are ganged together, (180 out of phase), so when you adjust one, you are actually adjusting both.  You might ask yourself what is the trade off for a differential tuner vs a standard tuner…  Not much the AT2K will tune a slightly larger range than the AT2KD, and that is about all…  The case is smaller for the AT2KD, so that is a plus in favor of the smaller differential tuner.

The idea of one less knob to set when changing bands, was appealing to me, and after all I was coming from an autotuner I had to manually adjust anyway, so I started looking for a AT2KD on QRZ.  Soon enough one came up used, and I purchased it from a very nice gentlemen in Florida.  It arrived, and I put it in service immediately.  The first thing I did was to create a template for tuning.  The Palstar tuners come with calibrated knobs for tuning, so repeatability was possible.  I manually tuned each band, and wrote down the values on the new template I created.  I then started using the tuner…  It is dead on for repeatably.  Once a setting was noted, returning to it got me the exact same SWR, every time!

AT2KD front view

Front Panel Controls:

The tuner has three knobs and four push buttons on the front panel.  The antenna switch is broken up into a Direct, and a Tuned side.  Each side has three positions, the Direct side, has Coax 1, Coax 2, and Bypass.  I use Coax 1 for my verticals, and Coax 2 for my dipole.  I use Bypass for a dummy load.  On the Tuned side, Coax 1 is the vertical, Coax 2 is the dipole, and COAX-BAL-WIRE for nothing.  The capacitance control is a single large diameter knob, with a gear reduction device on it, and a pointer.  The coil adjustment is a crank, and a turns counter.  The combination of the two allow me to get to any band and obtain correct tuning in very short order.  Speaking of bands, I am in AF MARS, and we are allowed to operate outside of the Amateur bands– way outside the Amateur bands.  This makes being able to tune anywhere important to me.  I have found no place I can’t tune my BWD-90 to, between 3 MHz, and 50 MHz.  So for MARS use this tuner is a winner.

The buttons on the front panel are for power on and off, and control of the power monitoring features…  This unit contains a full featured peak and average power meter, both accessible via a button press.  This is not a thrown together power meter, it is a high quality meter, and matches a Bird power meter in testing, as well as my Ameritron AWM-30 Peak/Average meter every time.

AT2KD rear view

Rear Connectors:

The rear consists of six connectors, Input, Coax 2, Coax, 1, Coax-Bal-Wire, Bypass, and Power.  As expected, Input is for where your transceiver output goes, Coax one if for whatever antenna you want to put on your first coax, coax 2 is the same only for a second coax, Coax-Bal-Wire if for your balun, and openwire feedline, Bypass is just another switch position, and could be used for a third feedline to your antenna farm.  I use it for a dummy load.  Power is just what you would expect, 12 Volts DC, center positive.  A brief note, the tuner will tune, without DC, but you will get no indications on the meter of any kind, so you do need to apply 12 volts to use this tuner.

Palstar Tuning Chart

Use:

The first thing I did was to copy the Palstar tuning template to my computer, and then fill it out.  I tuned up on each band, then wrote down the values, and finally went to the template and filled in those values.  This allows me to get on tune, in the shortest time, and not mess with things when I want to change bands in a hurry.  It took about an hour to go through all the bands, tune carefully, and then write down each combination of numbers, and finally transfer to the new template you see on the left.  I make small changes to the sheet in writing, then every so often reprint the page.  If you have a tuner that has calibration marks you should do this, it saves time every time you change bands.  Click the image on the left, and you will be taken to another page where you can right-click and download it.  This will save you the time of making a sheet for your tuner.  Once you have it, you will need to mask my numbers and put in your numbers.

I like the tuner, it matches my Elecraft gear in color and form, and it matches just about any antenna I can throw at it for the most part.  If your antenna is even close to resonance this tuner will match it.  It does not match my GAP Challenger vertical, (see review here), on 160 Meters, but that is not surprising as the GAP is designed for 75, and has a cap in to, so things get very odd once you get very far off 75 meters.  I also don’t want to subject that cap to the stresses of high power that far off frequency.  It does however match my BWD-90 on 160, which is a bit surprising, as the BWD-90 was never designed to operate on 160, but does a rather nice job with this tuner.  There is an interesting comment on QRZ.COM regarding 160 operation here, and why you should be careful using this tuner on 160.  If you own this tuner, you should read the comment.

As I mentioned upscreen, speed is an issue for me, and I have found that once I have the tuning template filled out, this tuner is as fast as an auto tuner…  I just set the inductor, and capacitor, and I am done…  I get 100% repeatability, the gear reduction is quality, and feels like metal, not plastic.  There is no backlash of any kind in either the turns counter, or the knob.  I can put the ALS-1306 amp in line and away things go, at full power in very short order.

Conclusion:

I am very happy with this tuner.  I would love their autotuner, but I will need to save my pennies to get it.  I would feel good recommending the AT2KD to a friend.  I was having an issue with my ALS-1306 blowing finals.  I believe my method for tuning was to blame.  I was tuning the autotuner, at maybe 2 watts drive, this would drive the ALS-1306 to 50 or so watts, then I would press the TUNE button.  The tuner would autotune, and more times than not the amp would fault during the tune phase, I believe this is what took out my solid state finals on the amp– twice.  I tune at low power using the AT2KD, most times it is so close I don’t have to touch it up, but now and then I have to touch things up.  I never use the roller inductor under power, just the caps.  So far, I have had zero issues with the amp even faulting out during tuning.

Using the tuner is fun, fast, and it seems a better match for the amp, so I am very happy with it.  I can now get a 1:1 SWR, not 1.2:1, or 1.7:1, but 1:1 every time on every band, with almost any of my antenna, and I can do it quickly.  The tuner seems to take power with no issues, no arc overs, and no problems of any kind noted.  If you have run power at the 1 KW level it is stressful on everything in your power chain.  When I made the KW transition, I had a PL-259 connectors die, (crimp connectors, which I will NEVER use again), and a cheap coax switch I owned start to get warm, KW levels of power test your system.  This tuner showed none of that, it just went in line and worked…  I like the tuner, and am most happy that I have one.