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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | Ameritron ALS-600 Help

Reviews Summary for Ameritron ALS-600
Ameritron ALS-600 Reviews: 187 Average rating: 4.2/5 MSRP: $1299.99
Description: 600W Output Solid State Amplifier w /Power Supply on 100/110/120V for US
Product is in production.
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N2UJN Rating: 4/5 Dec 22, 2017 10:59 Send this review to a friend
Updated ALS-600 input/output pwr link  Time owned: 3 to 6 months
In the previous review post, for some reason, the link to the graphical results for power in/ power out does not resolve. Here is an updated link:

ALS-600 Power Input/Power Output Characteristic
Audio Input.
N2UJN Rating: 4/5 Dec 22, 2017 04:59 Send this review to a friend
Good 400-500W Amp  Time owned: 3 to 6 months
I purchased a used ALS-600, a later model with A B REMOTE ports on front, with new finals from Ameritron in late September of 2017. Detailed power input/output characteristics reported in this review below.

In four months of various testing and use on all bands I have not had a "problem" with the amp. I gave the amp a 4 instead of a 5 because: a) to really achieve 600 Watt output routinely on 10m-40m you have to run at or near 100W input. However, running at 100W input, all the time, is reported to cause the input resistor attenuator to degrade with time, ultimately causing component failures downstream of that resistor. b) Also, with new finals, for me, and, for many others, the power output on 80m peaks at 500W with 100W input. Extensive power output testing shown below.

IF you are looking at a highly capable amp to run continuously at 450-500W, and achieve long FET life, then, this amp IS a 5. But, advertised 600W output coupled with extended long life, based on all reported data, is a bit of a stretch. Hence, the 4.

I have tested the amp both with the ALC and without the ALC. A proper adjustment procedure for setting the ALC for the ALS-600 may be found at:,69246.msg503528.html#msg503528

My audio signal is clean with or without use of the ALC on the amp assuming I have properly adjusted the ALC on the radio when not using amp ALC and properly adjusted the ALC on the amp when using it. Also, the input output power characteristics are identical with and without use of the ALC, except, with ALC the power output is controlled by the ALC SET control on the front of the amp (after setting the radio input power level high enough to reach target operating output power).

Some points of observation:
1) The amp does (by design) fault if the reflected power exceeds 50W, which, if you are running 450W out, is an SWR of 2.0.
2) I use the amp together with an old Dentron Monitor Tuner higher power tuner. My antenna's SWR does change as a function wx (wet, snow, dry, etc.). I could probably get by without the tuner most of the time, but, not all of the time. In the case of a tuner with a bypass, then, the full benefits of solid state can realized (no need to tune SWR at each frequency). Otherwise, with a tuner, ALS-600 use is very similar to a tube amp. Each frequncy has to be trimmed to match the antenna impedance.
2) The amp also (by design) faults if: the band switch is left at a lower band frequency than the actual operating frequency. (ex: bandswitch set at 2.3-4.4, actual op frequency is 14.225 MHz).
3) The amp does not fault if the bandswitch is set above the operating frequency. (ex. bandswitch set to 8.0-14.5, actual op frequency is 7.225 MHz).
4) At least for me, fan noise (amp and PS) mandates the use of a headset (Yamaha CM500). With a headset, no problem.

Power Output Characteristics: ALS-600
During my own reviews of this amp prior to purchase I could not find a detailed power characteristic published for the ALS-600. I have carefully developed, for my amp, the power input/output characteristic curves in Watts for 20m, 40m, and, 80m bands for audio input. A graph showing these curves may be found at the below link. These data are in approximate agreement with the 90W input data reported by AD5X.

Tabular Power Characteristic Data is below. I hope this helps folks......I see a lot of different single data reports like "35 Watts gives me full output". I doubt those reports greatly, unless someone has removed the input resistor attenuator. I hope this data helps folks trying to decide to buy this amp or not.

Note, there is a reference on the web that shows how to mitigate the measured and commonly reported lowish power output on 80m with cap bridges. It does not really bother will leave it.

My serial number: AL-600-16059 (has remove A/B inputs on front).

Tabular Power Data

20m (Watts)
0 0
10 45
25 125
50 350
60 425
75 550
100 625
K9HKS Rating: 3/5 Dec 5, 2017 05:55 Send this review to a friend
Problems but solvable  Time owned: 0 to 3 months
Purchased the ALS 600S Amp.Low output around 400 watts.Within a few weeks no output. Called Ameritron and after trying several suggestions I had to send it in for repair. All finals were replaced. Reason given was Chinese finals. Turn around time after repairing was great. Now have problem with meter lamp in switching power supply burning out. Ameritron sent me 3 replacements. Burned out again waiting for new one and they are adding a resistor to try to fix problem. I like the way the amp performs but it has not been real reliable.Its still in warranty and Ameritron so far has tried to resolve the problems.If I could do it over I would not buy the switching power supply
PA3GEG Rating: 3/5 Dec 4, 2017 16:15 Send this review to a friend
ALS 600 update  Time owned: 0 to 3 months
Well here I am again. After 5 weeks I called my dealer in the Netherlands if my ALS 600 was already repaired. They could not find the problem because the finals were ok, so probably problem with the print. They made me an offer I should pay 115 euro's and they would send me a new one, but now with the switching power supply. I found it a good deal and I think but I am not sure perhaps Ameritron told them to do so, but it could also be the service of the dutch dealer/importer. The power supply is more silent than the heavy linear type, but the amplifier itself Ameritron claims it is extreme quit, this is not the case it is quit noisy in my opinion. When the amp gets warm the power supply makes a strange noise even when the little fans inside are not in use. that is silenced after cooling down, A phone call to Ameritron doesn't give a solution. So I think I stay with it for now. It shows up after longer qso's in cw 200 watts after 15 minutes, in ssb 400 watts about half hour. My impression of the ALS 600 is for about 300 400 Dollars more I think you get a better product from a different company with everything in one apartment so not an external power supply. For me to be honest my last Ameritron. In the future I will try a different company, I suffer from Tinnitus so it could be when this noise irritates me to much I will get rid of it and try something else. The power is ok it gives about 600 watts in a dummy but I am only allowed to make 400 watts pep maximum in The Netherlands. I must say this amplifier section makes no strange noises when it is getting warm no thicks, the other one did when it got hot. main Problem from the Ameritron company is the should test their amplifiers better before they are shipped to the custumors.
PA3GEG Rating: 2/5 Oct 5, 2017 03:15 Send this review to a friend
finals blown out  Time owned: 6 to 12 months
I liked the amplifier at the begining, but now after 10 months the power went doen I only have 300 watts now, likely one pair of mrf150 died. I have send it too my dealer and hope they willfixe it under warranty. Don't understand it, it always worked good, protection worked and I don't push it to hard, only 400 watts legal output here in The Netherlands. I will send an update as soon I will have it back.
WA4DOU Rating: 5/5 Jul 22, 2017 15:23 Send this review to a friend
Very Good Amplifier  Time owned: more than 12 months
I've had mine for 2-2&1/2 yrs. Drive requirement is 28 watts on 30m to perhaps a high of 55 watts on another band or two, with average of
45-50, being quite sufficent. I don't generally like to push any amp very far into gain compression, so I'm quite happy with 400-500 watts on cw, where I operate mostly. This amp has been completely reliable and
and I have no complaints! For qsk lovers, I recommend the AD5X qsk mod. Very well engineered and executed, it is inexpensive to perform and adds protection against "hot switching" relay contacts.This amp represents a very good performance/value/price point.
N6DMR Rating: 2/5 Jul 14, 2017 20:00 Send this review to a friend
Finals Going Out - Way Too Common  Time owned: more than 12 months
I have had two of the ALS-600 units. Both had finals fail, one unit failed twice in a few months. Poor design, insufficient cooling capability at the finals, way too hard to replace the finals and rating these at 600 Watts is pure advertising. They could be a nice unit for the price if they were somewhat reliable but the technology is inadequate for longevity.
KE4AMQ Rating: 1/5 Jul 14, 2017 13:31 Send this review to a friend
another bill  Time owned: more than 12 months
this is the second time the finals went out no more for me another 347.85
N0SQ Rating: 1/5 Apr 11, 2017 13:16 Send this review to a friend
kept going bad  Time owned: 6 to 12 months
I had one of these several years ago and had to have it repaired under warranty 6 times before I decided to sell it. The poor performance has turned me off to solid state amplifiers. Maybe they work better today but I'm reluctant to buy another one from any manufacturer.
KD0ZGW Rating: 4/5 Jan 31, 2017 11:31 Send this review to a friend
Good Amp  Time owned: 0 to 3 months
Bought this with the Ameritron auto band switch interface. 1st start up yielded a blown low voltage fuse. John from Ameritron was very helpful. Fuse was kind of buried so replacement could've been a lot easier. Amp operation has been fine and auto bandswitching is a real plus. Amp is more sensitive to SWR than I expected and it will fault out at anything over about 1.5. Overall a nice addition to my shack.
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