| KJ4FGI |
Rating:  |
2021-04-26 | |
| 811 Purchased used, better off with the AL811 H |
Time Owned: 6 to 12 months. |
I picked this AL–811 amplifier up used, the plate current meter went bad and I found a bleeder resistor that looked like it was soldered in but I could move it up and down.
I mainly use the amp on 20,40 and 80 m, I get close to 600 W out. I changed the 270 uF capacitors to 470 uF, now the plate voltage when transmitting CW doesn't drop down to 1400 V, it only drops down to 1600.
I change the 811 tubes to 572 B. this amplifier was made in 2008 and the 811 tubes it had an and were excellent and they say on the side of the tube made in Holland so I kept them as spares. If you can afford a few more dollars get the AL-811H.
This amp is still worth it and very easy to work on and I do recommend it, you may find a cold solder joint on it but that's par for the course because it's a great price.
I bought this for a great price used but if I was going to buy new I would've spent the extra money on the 811 H. |
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| W5ZYX |
Rating: |
2020-08-17 | |
| Good solid amp |
Time Owned: more than 12 months. |
I've had my AL-811 for several years and, with the exception of one 811A that went bad, it has been a solid performer. The only problem has been difficulty in getting it to tune on 160. I have a full size 160 meter loop with a MFJ remote tuner that produces a 1.5:1 SWR on all bands, 160-10, so I don't think the 160 tuning issue is caused by a mismatch. Other than that, the AL-811 perks along at 500 watts PEP output with about 50 watts of drive.
Update as of August 2020:
I converted the power input to 240 VAC, and decided to replace the 811A finals with three Matchlett 572B's and what a difference they make. Running on 240, the plate voltage increased to 2.0 KV. Being careful not to exceed 200 MA of grid current, which is allowable with the 572B finals, the amp now produces 600 watts of key down CW output with 72 watts of drive, and is indicating 725-750 watts of SSB PEP on a very accurate Palstar PM2000A watt meter, again with 72 watts drive.
I still haven't tried operating it on 160 with the new 572B finals but will probably wait until winter when the static crashes on 160 die down. |
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| W3VT |
Rating: |
2019-06-30 | |
| No regrets |
Time Owned: more than 12 months. |
| I bought my AL-811 from a local ham that never really used it. It truly was "like new in box". I have had ran this amplifier for 2 years now, working 120 countries, all 50 US states, and all during one of the worst solar minimums in our history. If I push it hard it'll do a solid 600w on most bands. I usually run it at about 450-500w and it never gets very hot and the meters look happy. I have broken through many pile ups with the combination of my modest equipment and well placed and well built resonant wire antennas. Sure, I could do better, but this amplifier, when properly tuned and not abused, will get you a nice signal increase and put you in position to make contacts. I use mine daily. Often switching bands and antennas requiring many re-tunes. It keeps on chugging along. I see no viable reason to upgrade. |
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| VK3KTT |
Rating: |
2019-02-09 | |
| if your on a budget this is a good amp |
Time Owned: 3 to 6 months. |
HI i got this amp a few months ago i upgraded my license so can now use an amp.in vk a 400w limit i had an ldg at600 proII tuner so didnt want a bigger amp. this was second had sold buy a tech who sorted it out int he first weekend i blew one of the 811 tube trying to tune on 30m with out the manual bought some 572b's for longer life and more Durability.
Simply with your tune settings it works very well and is quick to change band the instant on is great as well i use the arb704 with my ftdx 5000 and if i mistakenly put 200w in the rig winds back the drive . now i have a signal that is loud and at the bottom of the cycle you need that. if you can get one at the right price grab it all parts are still avaliable and its not hard to fix if you know what your doing. good job ameriton thanks. |
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| K4CWQ |
Rating: |
2018-01-17 | |
| Great Value |
Time Owned: 0 to 3 months. |
I bought my AL-811 used, with 3 new 572B tubes in it, about a month ago. I'm not an expert on amps or their components, but I see this amp as a great value. I'm retired with a very limited budget for ham gear, and I felt a newer amp a better alternative to an older used amp of the same power levels, such as SB-200.
My signal reports have gone from, "I can hear you just above the noise" to "solid copy, 20-over here." I hear a lot of these amps on the air and they sound good. I don't have $1,000s to spend on an amp and I don't think going from 500 watts to legal limit adds much extra signal. I run the amp conservatively at 450-500 watts and believe it will last many years.
The assets as I see them:
1. Price, price, price. More power for a low price.
2. Tubes readily available, at a low cost, less than $100 for 3 811A's. I'll replace with 811's rather than 572B's which cost much more and add no extra watts.
3. Replacement parts are common and readily available..
4. With so many of these amps in use, there's lots of info and tips on them.
If I had unlimited money to spend, I'd likely buy a solid state amp. However, the price of the AL-811 makes it the Best Buy for the money. |
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| N8FVJ |
Rating: |
2017-12-21 | |
| Excellent for price |
Time Owned: 0 to 3 months. |
This not a high-end amp by any means. But, it is well built. It has a 17lb power transformer that is of conservative design for a 600 watt PEP output amp. The high voltage 3KV bridge rectifier does operate a little more efficient vs full-wave doubler (see Hammond transformer tech data).
The Ameritron design 2 to 1 rectifier peak to operating voltage does seem to be reliable, but I would prefer at least a 4KV bridge. I will change to 6KV with replacing each rectifier with two in series. That 'magic' 2.5 to 1 ratio peak to operating voltage design standard in ARRL Handbooks works and will survive any 120/240 volt line spikes!
The 811A tubes are a crap shoot per other posts. I bought my AL-811 used with newer RCA 811A old stock tubes. These tubes have the plate fins and are much more forgiving during tuning. Also, the RCA have much higher vacuum vs new Chinese 811A tubes. High vacuum is important! Tubes should be at 10 to -6 Torr or higher vacuum. I suspect the Chinese are as low as 10-4 Torr.
You can install Chinese 572Bs, but some have also experienced internal tube flashovers anyways despite the much higher 572B operating voltage. If you can find Cetron 572Bs, the amp will never experience a flashover and tubes will likely last 30 years or more. With the 572Bs you will never melt the tube plates with overdriving or using high duty modes such as CW, RTTY or AM. I would limit the amp to 400-450 watts output unless using 572B tubes.
Low duty SSB will not melt tube 811A plates if properly tuned at 600 watts PEP output. I get about 600 watt PEP output using SSB with 50-60 watts drive.
Also, some have mentioned using 572B tubes produce lower third order IMD. I suspect it is still -30dB.
The amp does use the same power transformer as the 80 watt PEP rated AL-811H. So, 800 watts PEP is available from this amp with 572Bs. But, is it worth it?
The way to get higher power is to use the lower 100 volt buck/boost voltage transformer input tap and install a .1 ohm 10 watt resistor in series with the tube filament string to get the filament voltage back to approximately 6.3 volts. The capacitor bank is maxed out with four 450 volt rated capacitors. You will need to replace the original power supply capacitors with 600 volt 'snap-in' capacitors of 180uF each.
The amp will operate with about 2100 volts no load to 1800 volts full load on the 572B tubes. At 1800 volts the 572B start to wake up and will produce 800 watts PEP output, no problem.
I would rather just buy an 811H or larger amp as I believe 600 watts PEP ve 800 watts PEP will not make enough difference on the receive end.
All in all the AL-811 is a good amplifier for the money. But those Chinese 811A tubes are somewhat of a 'crap shoot' even if inexpensive to replace.
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| KN6Q |
Rating: |
2017-02-17 | |
| Good value |
Time Owned: 0 to 3 months. |
What can I say about an amp that has been in production for 25 years that hasn't been said?
MFJ/Ameritron (despite selling legal limit amps) markets that the first 600 Watts is what really counts. So, never having owned an amp before, I wanted to dip my toe in the water, and this amp is is the least expensive currently made.
Probably more people opt to pay $100 more for AL-811H to get 200 watts more (which is a good deal), but figured I would save $100 for other gear and upgrade later if I wanted to.
I haven't used it in a "real" contest yet, but I've been able to bust through a couple of pileups on my first try. Being in the middle of a solar minimum, for the money, it's the best upgrade to my shack I've made in some time.
It's well made and seems to be forgiving to my learning curve on tuning it.
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| K1VCT |
Rating: |
2016-10-07 | |
| Zero issues |
Time Owned: 0 to 3 months. |
I got this "used" for less than half the price of a new one. It was about 3 years old, according to the included original invoice. Not a spec of dust inside. The 10m "green wire" was still in place. The tubes were devoid of any signs of abuse.
Hooked it up, tuned it, made a contact. Zero issues.
So far so good, its my first amp. According to meters, I'm driving it with about 60w and getting about 500w peak on SSB. Really can't complain thus far - except - the 20m input tuning is a little off about 2:1. The rest of the bands are about 1.2:1 on my transceiver. I don't have a slug tuning tool handy, but looking at things from the back, it does not appear to have been "readjusted" from the factory setting. No problems are anticipated with re-tuning. |
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| N0HAN |
Rating: |
2016-08-04 | |
| basic amp ! |
Time Owned: more than 12 months. |
| Got one of these broken poor solder joints on plates by the choke used silver solder on it and replaced tubes fired it up 600++ wts not bad for broken junk got fot $100 and new tubes! |
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| W0TDH |
Rating: |
2016-06-18 | |
| Most economical for the $$$ |
Time Owned: more than 12 months. |
My humble AL-811 was a Christmas gift from XYL 12-25-1993.
After a few glitches early on(replacement parts provided free ), it made all the difference
when my Elmer and I were in QSO's four times a week. (40Mtr CW)
He lived in STL with a lot of noise. The increased signal to him was a blessing.
My Elmer Passed and is a Silent Key. Mostly AM Ops for several years now, using
the AL-811 amp. Mostly 10Mtrs when Band opens.
I have gone through several sets of 811a's since 1993. They used to be 12.00 each :))
I have tried a set of 572B's....and flattened them in no time at all. ( according to RF Parts )
Too much heat. Went back to 811a's and added an external fan on exhaust port with five 1/2" holes in right
side of case. Stock fan was left in place. Tubes seem to last longer now.
AM Ops are at 100watts output. ( 400 wts Peak, 100% Mod). Long winded transmissions are the Norm.
Problems arise when I forget to plug in the external fan.....thus overheating tubes.
The amp is great for helping the Morrow Twins, Gonset G-28 and several AF-67'/68's
to achieve 100wts output using a fixed 6db attenuator to lower exciter output to about 8wts.
Only problem I have is with heat. Better tube life has been achieved with addition of the external fan.
This amp was not designed for longwinded AM Ops, I understand that.
I have pretty much learned to live with losing tubes due to heat, however there must be a better solution,
other than placing the amp in an ice box, ice house etc......perhaps cooling thermal couples on the air inlet....:))
The solution is most certainly not using 572B's. I find them much harder to cool. 811a's seem to shed heat better.
No complaints, just some hands on with the AL-811 amp and can not afford a different amp.
Using amp on CW & SSB I suspect the tubes would last a very long time.
73,
WØTDH
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