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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | Ameritron AL-811H Help

Reviews Summary for Ameritron AL-811H
Ameritron AL-811H Reviews: 164 Average rating: 4.5/5 MSRP: $899
Description: 160-10 meter RF Amplifier. 4 811A tubes
Product is in production.
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KA2UUP Rating: 5/5 Sep 10, 2013 08:39 Send this review to a friend
11 years and still going on strong  Time owned: more than 12 months
Only problem I have had was with what looked like runaway current about 5 years ago. I sent the thing to Ameritron and it was repaied within the week for $60, including the shipping. I modified mine with 2kV rated capacitors and also installed a softstart module from another vendor who had them some years ago. I tried the 572B tubes and worked very well. However, I returned to the original 811As after I broke the cap off from one of the 572Bs. Still giving good service at the rated 600 W on CW and 800 W p-p on SSB with about 65 W of drive from an IC-746.
KF6OCI Rating: 5/5 Aug 16, 2013 14:56 Send this review to a friend
Good Practical Amp  Time owned: more than 12 months
I have two of these, didn't know anything
about them at the time, but there is so much
info on line that learning about them inside and
out is quick. Easy to work on and there are
numerous Hams including yahoo groups that
kindly help. Great learning experience.
I'm easy on my equipment, don't push.

N4JA Rating: 3/5 Aug 15, 2013 12:10 Send this review to a friend
Changing input coax helped  Time owned: 0 to 3 months
I'll have to take back all I said before. Today, I was going to try to tune the input circuit on 10 and 12 Meters. I tuned up the amp on 10 meters with 5 watts drive. I moved the LP-100 from the output of the amp to the input. I had a 16 inch jumper of RG-213 from the LP-100 to the input of the amplifier. I had been using the SWR on the exciter on my other tests. Using the LP-100, I was able to get the input SWR down below 2:1. I determined that either the RG-8X I had been using was not 50 ohms or the length was wrong. I changed out the jumper from the exciter to the amplifier from 5 feet to 3 feet. Now I get drive on both 10 and 12 Meters. But you still need an external wattmeter to tune up the amplifier. With the new length of RG-8X cable the SWR meter on the exciter now reads 1.6:1 on 28495 and I get 495 watts out on 10 Meters with 60 watts drive. The input SWR on the exciter says 1.2:1 on 12 Meters and I get 514 watts out on 24945 with 60 watts drive. Now none of the other band's SWR were affected. I still get over 600 watts out on the other bands with 60 watts drive to the four 572B tubes. I am still running the tuning slugs all the way out the back on the two input coils on 20, 17 and 15 Meters. But I did notice the SWR reading on the exciter's SWR meter came down to 1:1 on 15 meters, instead of 1.2:1 before I changed coax jumpers between the exciter to the amplifier.
The main problem I was having with the input SWR on 20, 17 and 15 meters is still like it was before. To get the input SWR down below 3:1 on those 3 bands, I had to run the ferrite tuning slugs all the way out of the back of the coil assemblies.
W3LQ Rating: 4/5 Jul 31, 2013 05:30 Send this review to a friend
Good amp for the money  Time owned: 0 to 3 months
Picked this amp up on Ebay at the same time that I picked up an 811 (pice was real good on both, and it never hurts to have a spare). The amp arrived in very good shape; one of the tubes, however, did not make the trip well and was DOA. I bought a new set of 811As, and replaced the dead one.
This amp had the same little problem that the 811 I bought had--shorted D-16 diode in the grid circuit. Replaced the diode, and all was well.
Run this baby at 500 watts key down and it seems to like that operating zone. Run the amp through my Ameritron 1.5 KW, and all is well.
What am I doing with two Ameritrons? Well, the price was right. I like these amps a lot, but if the right Ameritron 80A or 80B presented itself, I would probably switch.
WA1RKT Rating: 2/5 Jun 30, 2013 12:06 Send this review to a friend
Poor reliability and workmanship  Time owned: more than 12 months
Purchased a new AL-811H in mid-2009. Got it home and it was DOA (don't remember the symptom now). Took it back to the dealer and got another one, brought it home, also DOA (same symptom). Decided to take a look, pulled the cover off, found that a length of wire that went from the bottom to the top of the chassis was pulled tight around a sharp chassis edge which had cut through the insulation and shorted the wire to ground. Fixed that and the amp worked. Notified the dealer and Ameritron on the assumption that the first amp probably had the same problem.

I am now on my fourth set of tubes and the amp has been back to Ameritron for warranty work twice. The first time, I reviewed my tuneup and operational procedures with Ameritron engineers and they agreed that I was doing everything correctly. The second time I had them upgrade the amp from 811A's to 572B's and had the grid current limiter circuit installed. That set of tubes (first set of 572B's, third set of tubes) lasted a bit over a year, and I have this afternoon replaced them with a new matched set from RF Parts, having given up on wherever Ameritron gets tubes.

Removing and replacing the top cover this afternoon, I was reminded that the cover mounting holes don't line up very well... another example of poor workmanship.

Yes, the AL-811H is inexpensive as compared with other amps, but what good is that if the workmanship is poor and it won't last much more than a year without some problem that takes it out of service? As I said I reviewed my operational procedures with Ameritron engineers and they agreed that I'm doing everything correctly, so it's not like I'm abusing it. Just to be sure, last time it was in for warranty repair I had them install the grid current limiter, which now shuts the amp down at the absolute slightest provocation and on average doesn't let me output more than about 500 watts PEP without cutting out... and it still went through a set of tubes in little more than a year.

For comparison, I have two Collins 30L-1 amps, one with 572B's and the other with 811A's. I drive them both at least as hard as if not harder than the AL-811H and they Just Work, never a problem.

Very unhappy and dissatisfied with Ameritron.
VK2ANS Rating: 4/5 Jun 29, 2013 14:46 Send this review to a friend
Needs work!  Time owned: more than 12 months
My AL-811H amplifier was quite susceptible to self-oscillation - especially up on 10m - even though this model has RF negative feedback fitted. After much experimentation, I found I had to unwind all four plate parasitic suppression coils by one turn each and insert a 100 ohm 3W non-inductive resistor inside each coil in order to stabilise this amplifier. I made sure each coil was air-wound (not close-wound) around each resistor. Next, I removed the 2 wire links from the 10m PA coil and the bandswitch, replacing them with a 10mm wide thin silver plated copper strap from the 10m coil tapping to the bandswitch. This resulted in about 50W more carrier output (50W drive) and smoother tuning. I then moved the 20m/30m tapping further down and onto the top of the PA coil, effectively adding 1/2 a turn. This improved 30m band output at no expense to 20m band output. The 80m tapping did not need altering. I then checked and retuned some of the input coils. My excellent Coaxial Dynamics 83000-A true peak reading RF wattmeter indicates around 1kW SSB output on most bands with 100W of drive. These amplifiers should never be continually driven that hard, of course. I find it's best to start tuning up this kind of "low plate dissipation" glass tube amplifier with only 5W of drive. The best drive level for testing and experimenting is 50W. My spectrum analyser shows its spectral purity is reasonable (at best), being around -20dB for the 2nd and 3rd harmonics - but it's a heck of a lot more stable now!! Ameritron really should upgrade these amplifiers by fitting a new bandswitch with individual WARC bands selection, better quality HT supply resistors and electrolytic capacitors. A bigger mains transformer would certainly help - especially with the AL-811HD 572B 4-tube version.
RA2FN Rating: 4/5 Mar 27, 2013 12:53 Send this review to a friend
This is a good device!  Time owned: more than 12 months
This amplifier is already used 4y. For this time he much worked in field conditions. Has Proved;proven to be itself reliable device, nor reek did not conk. Not very heavy. It Is Intended and undemanding in usages. The Price wholly acceptable.
I am a dialect yes this amplifier!
WH7DX Rating: 4/5 Feb 5, 2013 09:22 Send this review to a friend
Happy User  Time owned: more than 12 months
After a year of use, I'm still satisfied with the 811H. Pushing 75w from my Kenwood 570, into a hexbeam and dipoles, I'm getting 600-700w and solid signal reports and audio reports. I prefer to use about 75% output for a clearer signal it appears.

I give it a 4 versus a 5 because of the click on TX but that's not a big deal for me.

For about $900 it's certainly worth the price. I just can't see spending $1000-2000 more for a couple S units.. if that.

Like everyone else, post the best load and plate settings for band right on the amp and tuning isn't a big deal.. I kinda enjoy it.


N4WRE Rating: 5/5 Dec 27, 2012 07:52 Send this review to a friend
All you need  Time owned: more than 12 months
I have had my 811H several years now, bought it used and have no complaints. It is really all the amp anyone should ever need. Cheap tubes, plugs in any 110 outlet, and just plays. On the air I bet you can't tell any difference between the 811 and my 1500 or 1200. I would like to have another one or two. Hard to beat for the money..

Marty N4WRE
K1EHZ Rating: 5/5 Sep 29, 2012 15:58 Send this review to a friend
Excellent Value  Time owned: 3 to 6 months
This is my first power amplifier after several years of 100watt transceiver operations and some QRP. My operating position is compact so among the considerations for getting an amplifier was power requirement, size, and placement. I decided to re-configure some shelves and squeeze the amp onto the table next to the ICOM-736 that drives it. I bought the 811H used, in fine shape and wired for 120v. After reading the helpful articles by W8JI, I also bought a matched set of un-installed Taylor 572B tubes from another ham. After trying out the amp to be sure it survived shipping, I performed the grid grounding mod recommended by W8JI and added the gas clamp tubes, now available from Ameritron, on each side of the filament circuit. I re-assembled the amp and installed the 572Bs. The amp has worked very well. The ICOM 736 and the 8llH are doing fine on a single 15amp circuit along with a few small accessories. The 811H is forgiving when I forget to change the band switch or inflict some other insult on it. Power out is normal across all bands, though on 10m I need to increase the drive. I usually drive with 65 to 70 watts and get 700 to 800 watts out. 10m needs a little more drive so I may tweak the adjustable coil for that band. I receive good audio reports and the additional power is very helpful in DX pile ups. Anyone contemplating an 811 series amplifier should review the pertinent material on the W8JI web site (he designed them) at I should mention that I upgraded all of my coax jumpers and runs to the antennas to RG-8U type, although some say short runs of lighter coax should work. The 811H is a great value and I am very pleased with the results.
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