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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | Ameritron AL-572 (not B) Help

Reviews Summary for Ameritron AL-572 (not B)
Ameritron AL-572 (not B) Reviews: 17 Average rating: 4.5/5 MSRP: $1399.35
Description: 1300 watt pep out on 160-10M
Product is in production.
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VK3BL Rating: 5/5 Oct 24, 2016 22:33 Send this review to a friend
Great performance on a budget  Time owned: 3 to 6 months
I previously had an early 90s Ameritron AL-811 which I liked, but always wanted something a little more refined; the AL-811 doesn't have neutralization, or dynamic bias control which it really could use especially when run at lower than maximum power.

Anyway, an excellent condition 2010 model AL-572 came up on the second hand market, and I was intrigued, as amplifiers don't come up often in VK.

I was a little hesitant at first because it uses four 572B tubes, which many will know were unobtainable in 2015, however Shu Guang in china seems to be back in production with a better than ever model. I'm currently using the latest generation tubes as a couple went soft in a recent contest, but hey, they were 6 years old.

So far so good. I love the amplifier itself - it is very easy to tune, and the vernier dials ensure it isn't peaky.

Power output is phenomenal - 1200 watts carrier or over 1300 watts PEP into my Bird 8201 dummy load, not that we can use that power in VK, but it is nice to have a lot of leeway as tubes go soft before they need replacement. A set of 811As could easy get soft enough to drop below our legal limit within a year, but with 4x 572Bs there is a lot of life left in them!

The other plus side is the amplifier actually likes running at the VK legal limit. Some amplifiers, like the AL-811 don't have any form of dynamic bias, and as such, run the tubes pretty hard even when keyed without carrier. Just try it. Key up an AL-811 with no signal input and watch the plates start to glow!

So yeah, I'm really happy with this amplifier. Nice and simple, easy to work on if every needed, and will actually run at our legal limit without cooking itself to death (many high power amps struggle with efficiency at lower output). The fact that the tubes can go mighty soft before needing replacement is a bonus!

A great simple amp with loads of power for anyone, good bias management, a great price point.

Of course I would like a more refined amp, but this pristine example cost me peanuts for a kilowatt class amp. Now all I can do is hope our regulators see the light and I can finally use it in all its glory.

Oh and the real bonus? If 572Bs ever dry up again, the AL-572 comes with a transformer tap so you can run 811A tubes! How many amplifiers out of the box can run another tube without any modifications? Great forward thinking by Ameritron.

My next amp will be a solid state one, but I can't see my lovely AL-572 ever leaving the shack.
K5AX Rating: 4/5 Oct 17, 2016 08:40 Send this review to a friend
AL-572 Lemon Bought At Hamfest  Time owned: more than 12 months
Bought one not working at hamfest. Found the 3055 and 3906 shorted. No bias. 51 ohm resistors in tube bases open. PCB around 3055 and 3906 mucked up from soldering and unsoldering. To make long story short, found poor soldering in PA around neutralization cap. Resoldered PA. Replaced 51 Ohm 2W resitors with WWII 51 ohm carbon 2W bought on Ebay. Put XSTR Socket at 3906. Put burilium block on heatsink of 3055 and upgraded 3055 to ST Micro 15A device. AMP orig used MJE3055 a 10A device. Subsequent tube shorts and general low qual tubes have been changed out. Otherwise, at this time the AL572 is pretty reliable. Just of victim of Ameritron QA (Although I have an AL1500 running 20 years with Zero Probs).
KZ4B Rating: 5/5 Jun 14, 2016 21:51 Send this review to a friend
A Favorite Amp,--But Beware Of Neutralization Issues  Time owned: more than 12 months
I have one or more of every current model Ameritron amplifier made (except for the AL1200 which uses a potentially extinct 3CX1200 Eimac Tube and the AL82 which I would love to have). Of all these amplifiers--my all-around favorite is the AL572 because I CAN LIFT IT at 50 lbs. and it will put out the legal limit on the lowest three bands when wired for 240 VAC!

So why does it have only a nominal 4.0 over-all rating if I think it is so great? My opinion is (based on my review of the comments below and my own experience with mostly triode-based amplifiers which MUST be neutralized) that improper neutralization causes often catastrophic tube and other component failure in many cases.

The AL572 (and incidently also the AL811H) utilize four (4) parallel (late 1930's design glass envelope) triodee tubes which have a HUGE amount of internal grid-to-plate inter-electrode capacity. This internal coupling capacity can generate feedback causing potentially catastrophic parasitic oscillation unless properly neutralized via the adjustable teflon "post" capacitor centrally located between the four tubes. It appears that some amplifiers came from the factory with improperly adjusted neutralizing capacitors--but most often the problem appeared when an amplifier was re-tubed without re-adjustment of the neutralization capacitor in order to compensate for the change in inter-electrode capacity due to variances in different manufacturers tube designs.

When replacing tubes that are not identical in make and therefore design, contact Ameritron Service for the detailed adjustment procedeure. In very general terms, the idea is to adjustv the neutralizing capacitor to minimize any observed variation in grid current when tuning the plate tank circuit capacitor throuh the resonance (maximum plate current/power output point. Failure to neutralize the Subject Amplifiers can result in erratic operation and often catastrophic component (mostly tube) failure.

The 811A tubes (with thin metal plates) used in the AL811H Amplifier have a very marginal plate power dissipation rating of 65 Watts each. However, the 572B tubes (with thick graphite plates) used in the AL572 Amplifier have a very, very conservative 160 Watt rating per tube. The AL572 Amplifier probably works out to the equivalent of 1000+ Watts total plate dissipation (250+ watts per tube in reality). In short--the AL572 is a mere 50 lb. amplifier with plate dissipation and output power which almost rivals the very excellent 80 lb. AL82 that uses a pair of 3-500Z's at the legal limit plus.
W8ASP Rating: 0/5 Jan 9, 2015 15:49 Send this review to a friend
Obsolete DONT waste your money!  Time owned: 6 to 12 months
This unit is obsolete because you CANNOT purchase replacement tubes from the manufacturer Ameritron or anywhere else! If you do find any from what I've learned they are most likely old stock returns or rejects or low quality Chinese tubes that won't hold up or last you for very long. Rf parts is trying to do something to help by having these made again in China. This has been a very slow process for them and if you called them today and try to order any you will NOT get any! They have changed their estimated times so much that I don't think they positively know when they will be available to the public for sale. There is a huge back order list they have to fill first and are not taking anymore requests before they can even open sales to the public again. I can't believe Ameritron was still selling this model to the public knowing the situation on replacement 572b tubes. I found out the hard way I bought the amp new from local dealer and about a month later ordered a set of quad matched tubes through my dealer from Ameritron. They were showing available on Ameritrons web site When I purchased it. Well the order never came and I found out they didn't have them and couldn't get them! That's when I started calling around trying to find a replacement set for back up. No way none available anywhere that were werthy. I cannot believe Ameritron would produce a product intenatley that they CANNOT support. So buyer beware and stay away from!
K5HSV Rating: 5/5 Oct 2, 2013 21:07 Send this review to a friend
1300w with 120v... Nice Amp for My Camper!  Time owned: 0 to 3 months
I purchased the AL-572 from HRO a few weeks ago to use when I took out my camper for a little R&R and QSO. I checked out the watts with a Power Master to verify to output. On 80 meters the amp put out 1100w with 75w drive. Simple in design, does what it is designed for. The amp did hit 1375w a few times with 100w drive but I tried to be easy on the tubes. It weights about 60 lbs. Nice bright LED lights on the meters. At this point, I don't have any complaints, other than Ameritron doesn't give you instructions on how to make the modification for 10/12 meter use. Hint... Hint... (Clip the green wire). No issues to report. At this time I can recommend the AL-572.
AA9NN Rating: 5/5 Mar 6, 2012 14:08 Send this review to a friend
Very Good Amp.  Time owned: 0 to 3 months
Saturday went up to AES in Milwaukee and bought this amp brand spanking new! I usally never do that! new...but I figured what the hell time to try new. I had one of these about 5 years ago and had the newer tubes in it(Taylor 572) worked 100% although meter was a little flakey.

This amp is latest serial ## Got it home after a stop at the "Brat Stop" with my Gal and opened it up checked all the internals, all good,did the 10 Meter Mod, and fired it up on the Bench. 2800V on the numbers! The best thing for these tubes is to let them run with no load for a bit, so took the Gal out for Sushi! and movie,Amp ran for about 5 hours. All Good! Took out the ALS600 and put in the AL572 Sunday AM.
70 watts CW on 40 Meters did 1225 watts out!
All Good, 50 watts on 15 meters did 1250!
worked all over the bands and worked the Contest and amp worked as advertised!
Input SWR is all good across the board.
Now, I bought this as I wanted a KW Plus on a 120V as I had my shack wired for 220 BUT needed 2 Circuts so I have 2 30amp 120V's in my shack.
and for the price, its a solid amp! I will take 1200 to 1300 watts for over $1K less than a AL1200.
all the best and have fun!

AB3ME Rating: 5/5 Dec 2, 2011 17:13 Send this review to a friend
great  Time owned: 6 to 12 months
Bought this amp from HRO about 6 months ago. I live full time in an RV and have access only to 120 volt service....and most of the time not that at all. For this reason, I chose the AL-572 due to the ability to change the taps on the transformer to match my input voltage. Ran the amp as is for about 4 months (taps set at 125 V from factory) After making the mod to allow 10 meters, the amp would do about 800 to 900 watts out with my input voltage of 118. HV reading of 2600 on internal meter.
Changed tubes to Taylor 572 from RF parts a month ago, and reset the transformer taps to 115. HV now reading 2800 per manual, and output of 1000 watts (PEP SSB) consistently on 17 and 12 meters. Definitely an improvement.
80 to 15 meters performance is at 1200 watts SSB (PEP) and was with taps at 125v, no change with taps at 115, but output is at 1200+ on these bands now. Maybe the Taylor tubes made the difference, or the change in taps on transformer. I realize the 2800 minimum HV is making the biggest difference, and am pleased with the performance. I drive this amp with my Icom 7600 at the full 100 watts. All in all, I am very happy with this amp, and feel it fits my needs perfectly primarily due to the ability to easily change the transformer taps, and easily replaceable 572 tubes Good job Ameritron. This far outperforms my old SB200.
W7DME Rating: 3/5 Apr 1, 2011 15:08 Send this review to a friend
Not good!  Time owned: 0 to 3 months
When I look at an amplifier add that says it will do 160 to 15 meters, I expect to be able to do so without having to modify the input tuning of the amp, that is, unless the add specifically says you have to modify it in some way to get the coverage it advertises, such as the 10 meter mod required. Ameritron does not reveal this until they have your money, and then only after you discover the high SWR on the input on the WARC bands and call tech support. It is no where in the manual or advertising. If you have a broadband radio driving it and no antenna tuner, you could damage the finals in your radio. Also not in the manual is anything saying you are'nt supposed to use an antenna tuner, even though they say the amp will stand 100 watts of drive and the normal radio can't put out any more power with or without a tuner and most radios today are 100 watt radios.

Shame on you Ameritron@!
K4RYR Rating: 5/5 Nov 27, 2010 07:26 Send this review to a friend
Nice Amp.- But Caution!  Time owned: 3 to 6 months
I have no complaints about the operation of the works great and requires very little drive to full output. However, having said sure to carefully examine the internal construction of the amp. when you take off the top cover to unpack around the finals. Mine had the meters installed incorrectly in a bind and not seated properly into the front panel openings, I also found a two lug terminal strip just floating in mid air and not secured to the chassis as it should have been. MFJ supplies a lot of good products for amateur radio and we are lucky to have them in the USA, but the quality control leaves a lot to be desired, so always carefully inspect anything you buy for mfg. problems.
N2JXN Rating: 4/5 Jul 11, 2010 17:41 Send this review to a friend
great so faf  Time owned: 0 to 3 months
Nice amp get rated output. Only problem was when I did the 240 volt conversion. Powered up the amp and R27 as shown on the circuit board 127 as shown on the schematic smoked. Replaced it with an equal and since no Problems. From what I understand this is normal for MFJ. Contacted Ameritron and they sent me a replacment under warranty
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