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


Reviews Summary for Ameritron AL-811
Ameritron AL-811 Reviews: 170 Average rating: 4.5/5 MSRP: $650
Description: Uses three tough 811A transmitting tubes
Product is in production.
More info: http://www.ameritron.com/products.php?prodid=AL-811
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K4CWQ Rating: 5/5 Jan 17, 2018 10:26 Send this review to a friend
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.
 
N8FVJ Rating: 5/5 Dec 21, 2017 08:31 Send this review to a friend
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.
 
KN6Q Rating: 5/5 Feb 17, 2017 08:49 Send this review to a friend
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.

 
K1VCT Rating: 4/5 Oct 7, 2016 18:03 Send this review to a friend
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.
 
N0HAN Rating: 4/5 Aug 4, 2016 07:14 Send this review to a friend
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!
 
W0TDH Rating: 4/5 Jun 18, 2016 02:49 Send this review to a friend
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,

WTDH
 
KL2EC Rating: 5/5 Jun 13, 2016 10:24 Send this review to a friend
great amplifier!  Time owned: 6 to 12 months
Never had an amplifier before this one. the learning curve was short and I really enjoy using this big box. I have read many varied reviews but I do like the perfomace.
 
KK4YDR Rating: 5/5 Jan 27, 2016 23:39 Send this review to a friend
Great little small amp  Time owned: 0 to 3 months
Got this amplifier in a trade from another station. It was about 6 months old at the time of trade, last month 01/16.

Amplifier makes about 500watts pep peaks in SSB. I haven't used it for other modes other than SSB. I could tune it a little more aggressively but the 811's aren't 3cx1500 tubes like so many tend to think. They are a durable little inexpensive tube and are pretty tough. I accidentally hammered them with a 200ma grid current spike not paying attention and my self-installed GOP circuit kicked in. The amp still makes 500 watts pep. Don't count on these making 600 watts as advertised. That is definitely an overstatement. These are super easy to tune. A little practice and you will be tuning it within 15 seconds on average after a band switch.

Great little amplifier for the money and it's small size. No frills, lots of excitement.

I am NOT going to sell this amplifier. I am going to get a legal limit next and keep this as a rag chewing amp when I don't want to run a 1500 watt space heater in my shack.
 
VA6DWH Rating: 5/5 Dec 4, 2015 17:23 Send this review to a friend
Great Value !!  Time owned: more than 12 months
Please dont expect this amp to compare to the big dollar rigs.....but for what it costs and its durability....ease of use.....and up to six times the signal out..!...Pretty hard to beat....I have a legal limit rig I use most of the time....but I do keep my 811 exercised....as an inexpensive second or spare amp its super value....and the tubes are cheap....other than some routine cleaning....never had to fix anything....Build quality is so so...if you get one that works out of the box.....and you drive it properly....chances are you will be pleased....Regards..
VA6DWH
 
G3ZPS Rating: 4/5 Nov 16, 2015 14:10 Send this review to a friend
Good for light use  Time owned: more than 12 months
Had this used amp for 4 years (its 8 years old), the previous owner put 572b tubes in it and gave me the 811s as spares. It has light use - which is probably what its best at, I don't push it hard with my old FT902 and I don't use a speech processor. I cut my teeth on tube gear so I can tune it very quickly. The one problem I had was a failure to go into transmit caused by one damn 1/8 Watt 10ohm resistor in the little 2 transistor relay switching circuit going open circuit. Getting to it (or any component at the back of the amp) is a complete pain, I had to take the back panel off and release enough of the wiring on the one large double sided PCB to get to it. This is one area where the money is saved, put most components on one big board. Its not a contesters amp, don't thrash it for every last watt, expect the odd repair and it will keep going
 
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