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Reviews For: Ameritron AL-572 (all models)

Category: Amplifiers: RF Power - HF & HF+6M

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Review Summary For : Ameritron AL-572 (all models)
Reviews: 74MSRP: 2400
Description:
1300 Watts PEP SSB nominal power out on 160-15M. WARC bands and 10 Meters with reduced performance - user modified for 10/12 Meters with license. Uses four 572B tubes
Product is in production
More Info: https://mfjenterprises.com/products/al-572
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00744.1
K3HVG Rating: 2021-04-05
Looks like a very nice unit! Time Owned: 0 to 3 months.
Just got a new HRO-provided AL-572 on the air. Everything looks good, so far. Power out is spec as are all operating parameters. I still have some trepidation regarding the questionable Chinese tubes. I guess time will tell. I notice a number of mods on various sites, all purporting to either correct Ameritron design deficiencies and/or component reliability. I will do none of those during the warranty period, however. One question... What is the difference between the AL-572 and the 572B? I can see no difference, whatever. Maybe just hype?
K5AX Rating: 2020-02-03
Good Amp Time Owned: 3 to 6 months.
Only problems I have encountered were caused by crappy Chinese tubes. Currently all my tubes are good, and the amp is working perfectly. 900W on 10M, 1100W on 15M etc. Actually a nice unit.
Additional info: May 2018: After running the AL-572B for about 5 years I sold it at a Hamfest. A couple things about it, if you plan to run one. Get some 51 Ohm 2W bakelite resistors (Ebay WW2 surplus) for the tube bases (1 ea) as spares. They can blow open from the Chinese tubes. Also get some higher power 2055 Pass transistors (ST Thompsons). Put the small bias transistor in a socket. With this knowledge, the amps last a long time (unless you get another bad Chinese tube). The transistor socket for the small bias transistor and a bigger ST brand 2055 pass transistor, and spare 51 ohm resistors make the common failures real easy to fix.
N3TOG Rating: 2019-12-29
Dealings with Ameritron very very poor Time Owned: more than 12 months.
Truely awefull experience with amp and ameritron service. Soon after I bought the radio I was returning it under the warranty. It would run at 1300w, then 900, 600 to nothing.
They kept saying I was doing something wrong, I never over drived it. After I got it back the problem started over again, so I sent it back, they said they had to replace the tubes, I sent it back and they charged me for a tube change. So when I got it back same thing all over again. People had the same problem and they told them the same thing. So come to find out they were getting bad tubes and charging us to install them. Two things from this, never buy new from ameritron dealing with tubes, let the first owner go through hell. Forget the second thing so mad bout an expensive boat anchor.
VK3BL Rating: 2016-10-24
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: 2016-10-17
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: 2016-06-14
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.
KD6RSQ Rating: 2015-07-15
great amp Time Owned: 0 to 3 months.
I bought mine used (15 years old) with taylor tubes and it works great. The reviews I see that are negative it seems to be bad import tubes. I love mine
W8ASP Rating: 2015-01-09
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!
KE7BJQ Rating: 2014-08-25
Good with Caveats Time Owned: more than 12 months.
The AL-572 was purchased at HRO. Got it home and unpacked it. The foam around the amplifier was in place. I opened it up to install the tubes. The tubes were already installed and no packing material. I guess a convenience provided by HRO. Checked as many of the solder joints as I could which is usually a problem with MFJ. Didn't find any cold ones but didn't completely take it apart. According to the manual it will produce full rated output on 115 volts AC. Something about the winding of the transformer. Read through the manual several times before powering it on. Decided to try it on 20m. There was a Croatian station calling cq with quite a pile-up. Tried four times with 100 watts and no joy. Turned on the amplifier. Everything lit up including the tubes. Started tuning up into my oil can. About half way thru the procedure I encountered the curse of the Chinese tube. There was a loud pop. immediately put amp in standby and looked into the tube area thru the side vent. Three glowing tubes. One not. At this point I was wondering about other damage to the amp. I decided to test it. I continued the tune up process. Ended up with about 850 watts out. Worked the Croatian station with a 59 report. For several months I have been trying to find a replacement tube. One company has not had them due to trying to establish another Chinese factory. I guess we will have to get used to Chinese tubes. After having had an AL-811 this amp is much better. But I don't like the Chinese tubes and the scarcity of 572 tubes. I think my next amp will be solid state. Better technology there at the same price. Also the transistors are easier to obtain.
K5HSV Rating: 2013-10-02
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.