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Ameritron AL811 / AL811H

Just to verify

The 811 does NOT have the problem of needing a low dead-key....like the CB amps ?



So an 811 could take a dead-key as high as 100 watts ?


Ameritron says:

GENERAL SPECIFICATIONS:

Max. Drive Power Permissible: 100 watts

Typical Drive Rated Output: 50 watts



.
 
Max. Drive Power Permissible: 100 watts
Click to expand...


I would not dead key 100 watts into it, Am is tough on the 811`s.
Here is an example,
President Lincoln, 2 Watt dead key into a Sommerkamp DX 100 Amp
The DX 100 Is dead keying about 20 watts into the 811
The 811 Is keying a little over 120 watts and swinging upwards from there.

The 811 are not made for a lot of Brick on the key Time.
About 300 watts is all you should ask of the 3 tuber on AM/FM
( the manual states 400 watts 1/2 hour keydown, 550 watts 30 second key down....600 watts PEP SSB Mode)


I Have seen many things used to key amps....the most creative was a old straight Key ( morse code key ) with a RCA cable hooked to it sitting on the floor, when stepped on, it it closed the contacts in the amp!
Here are some Idea`s
You could rig something like this up to work:

Momentary Power Foot Switch

Or here are a few choices to look at:
McMaster-Carr

An old sewing machine switch would work as well

Someone used to make a RF KEYER... cant remember who right now...that "sniff`s the rf and closes a small relay to key the amp.


73
Jeff
 
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FYI, the tubes in the AL-811/811H are already being run beyond their limits as far as plate dissipation goes. The three tuber should DK no more than about 100 watts and the four tuber about 150 watts if you want the 811A's to last any length of time. AM is really hard on the tubes and the power supply components.
 
Captain Kilowatt said:
FYI, the tubes in the AL-811/811H are already being run beyond their limits as far as plate dissipation goes. The three tuber should DK no more than about 100 watts and the four tuber about 150 watts if you want the 811A's to last any length of time. AM is really hard on the tubes and the power supply components.
Click to expand...

The Captain speaks the truth. Since RCA stopped manufacturing the 811A tube with the reinforcing bars on each side of the anode, the tube has never been as good. I've found the 811H amp incapable of sustaining a 200 watt AM carrier on 10 meters (or 11) without severe anode overheating. Well into the "cherry" red stage. Not acceptable for a stamped metal anode tube. You need graphite anodes to handle this. When the 811A tubes die, replace them with 572B Taylor brand tubes and they will last forever in these amps.
 
Having played with an AL-811 since Ameritron first made them (serial #13) I can tell you a few things that might come in handy.
The earlier models (no idea when it changed) had a problem with the metering, it just wasn't 'sensitive' enough, or way too sensitive, to ever get the thing tuned correctly. Almost never saw a 'dip'. Best use for the meters was for max grid/plate currents, then an external watt meter and tune for 'smoke', sort of. Typically, depending on the 'state' of the tubes, that ended up with less than 100 watts of drive. That's not 'dead key', that was maximum input power. Depending on the band of use, that resulted in an output of something between 500 and 600 watts, which is normal for this amplifier. I think I remember using AM mode once to see what it would do. I can tell you that you will never see 600 watts for more than just a few seconds. Or a better way of saying it is that the average length of normal AM use is limited to just a few minutes before you start buying tubes, if you try for that max output thingy. You can get away with about 600 watts in SSB, but you're talking about a 50% duty cycle mode, which is a completely different 'anni-mule' all together. Ask my wallet, it will tell you a 'sob-story' like you wouldn't believe.
Using 572's in an AL-811 or AL-811H.
It will work. It will not work well, depending on what you are trying to do, or accomplish. They will live longer than 811's even if you abuse them. The tubes will last longer, the rest of the amplifier will not. Count on making repairs. The total output using 572's instead of the 811's the thing was designed for, will be slightly less than you anticipated. Those 572's will not be operating in their optimal range (primarily plate voltage), because the typical AL-811/AL-811H can't supply that voltage without extensive rebuilding. (The AL-572 is -not- the same amplifier as the AL-811(H), compare them and see.) Something no one seems to remember is that when you swap out those 811's for 572's the 'quality' of the resulting signal deteriorates also, it's not just the output power thingy. Things start getting a bit 'mushy' sounding. Describe it however you want, but there is a difference.
And the most funnest part of an AL-811 (of any number of tubes) is the cooling! It will almost never be enough for 'comfortable' operating. Them things get hot, and so will you unless you've got a very nice air conditioner. One of the handiest features of an AL-811 is that they make nice coffee warmers, has a 'solid' top, no vents, set your cup on top! Very nice in the winter though. Extra cooling fan comes in handy, but there are 'catches'! That 'extra' fan needs to be twice as powerful as the stock fan or there's no benefit to an extra fan. Something else to think about is filtering the air going into the amplifier, wish all air cooled amplifiers had one'a them filters. (About like computers, open case, pour out dust/dirt, then look at the guts. Right?)
All this sounds like the AL-811 or AL-811H are terrible amplifiers, but they are not. They really are about typical for amplifiers of this particular tube type. If you want the things to last for any length of time, think conservative!! I'm glad I have had the one I have for as long as I have. Wish I had gotten it's bigger brother (3-500) to start with, but so what, I can say that about a lot of things (Maserati as a first car?? :)).
Most of the "but's" about '811s hold true for any tube amplifier (or transistor) in general, just different 'limits'. Make it easy for your self...
- 'Doc
 
Heres a nice foot switch. I use one and it works great! I use a heathkit SB200 for a driver or by itself and it likes 10 tp 12 watt dk 100 pep for drive. Does 125 watt dk and 650 or so pep like this. Most the time I drive it with a cb for a driver. 2 watts in 16 pep gives me a 30 watt dk 200 pep out the amp.

Jetstream
 
I have 2 ameritrons and a Yaesu 2100B my favorite is my Ameritron ALS-600 Its a solidstate unit with a matching 50 Amp power supply. This amp also would be a great choice although pricey but when you want all the filtering and convenience its simply a great unit hands down. You would need the 10 meter board to expand the frequency transmit coverage.

I had brought up the Texas Star amplifiers not because there anywhere near comparible nor did I say they were but you can find themused for a pretty good deal and with (thinking) about getting an amateur license spending that much money on an amp (for some) just really isnt that practicle in todays economy if you have the money then by all means let it fly on a second note they do have trouble with some of these newer ameritrons with coils and other components in some and I just thought that Ide hate to see someone spend that kind of money even before they get a ham ticket and have to go through the headaches that some do go through.

If you are looking at the 811H Ide suggest looking at the ALS-600 Ive seen some sell at pretty good prices (good deals) like I said its solidstate and if you have the money its the way to go theres no warm up idle time and no tunning and loading but still needs a exciter switch for the amplifier relay.
 
I will say that Capitan and Shock have valid points, I also should have said I am running JAN, brown base 811a`s that do have the bars on each side of the anode, and I have increased the size of the cooling fan.
I do not run FM with it, most of the time SSB, and AM ragchew on Sat Nights a bit.
I am tough on the old bird, but she is still alive and kicking....
Output is still good, and I have not melted a tube yet.

I attached her profile picture below...and Doc Is right, she is nice to snuggle up with on a cold december day, she makes you feel all warm and fuzzy.
Of course, I was not lucky enough to have gotten Serial Number 0000013, but now we know who did.


73
Jeff
 

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Thats like my Yaesu 2100B it sports those 572B tubes and those things are like a damn Timex watch they just keep going and going I had looked at the Ameritron 572 amplifier because of the ruggedness of the 572B tubes but had seen that Ameritron had some issues with these amplifiers. Afew guys I talk to on 80 meters had troubles with there 572B units but once the bugs are worked out I may just buy one. Ive also looked at the 811H which is yet another option you can get a set of tubes for $100.00 which is great.
 
If you are going to spend money on an amplifier why not get a good one to start with? I would have to say that an AL-80A or B model will put any of those 811's or 572 amplifiers in the shade without trying very hard at all. It uses a real-live amplification tube too. It costs more than a few 811's or 572's but one will do a lot more than a couple of either of the other two tubes. They will also be around for a bit longer than the 811's and 572's will be, I think.
I see no need of a solid state amplifier unless you are going to use it in a mobile, or portable situation. If you've got AC power available, why not use it, and that's typically less expensive than a power supply of adequate size.
The only other typically found amplifier tube that is close to as 'forgiving' as a 3-500 is a 3CX1200. May not produce as much power as other 'ceramic' tubes, but it's about as reliable as they get. Oh well, that's my opinion anyway.
- 'Doc
 
The only real difference between the 811A tube and the Taylor 572B tube is the graphite plate. That takes it from 65 watts to 160 watts anode dissipation. Using them in place of an 811A in AM service will extend tube life without any negative effects on the amp so long as you don't expect it to make any more power. The idea is not to get more power and then stress the tank and power supply components, it's to get the tubes to run cooler.

The AL-572 amplifier certainly has differences from the AL-811 series but those differences are only there to use the full potential of the 572B tubes graphite plate. Because the 572B has virtually the same inter element capacitances, the circuit requires no change to go from 811A tubes to 572B. Just don't exceed the amplifiers published ratings.
 
AL-811/Pretty good for the money

I have owned my Al-811(3 holer) for maybe 5 years now. I purchased it used for $325 with a soft set of original 811a's in her. I have found it to be a decent little desk top amp. I have replaced nothing parts wise but the fan and the tubes. The 811a's are not a bad tube at least the old RCA's/Centron's/JAN and Raytheon's, but alas getting hard to find. They are twice the versions now available.
I purchased couple different Chinese type when I replaced the others. The first was made on the same line as Taylors, nice full output but anymore than 50-Watt drive on SSB and they will melt down in about a years average use.
I then purchased a set of PENTA Brand, they were sold as better built and much like the old styles. They looked good, better output about 700w pep with 50w drive on SSB....They went to about 400w and holes in the plates in about 6 weeks.
I knew I could drop 572B's with no mods, so I purchased a set of Svetlana's from K5SVC (I also purchased other tubes from him, never did me wrong). He told me he thought they were the best he had seen and used.
I must say I was quite impressed. Heavy glass/ceramic bases/silver plated anode caps.
I run the amp on 240vac/Plate voltage runs from 1750-1850vdc depending on the line voltage(235-242vac) I live in HOOTERVILLE remember...with 65w drive I see about 750-900w pep depending on the band...(10m about 650w) (only 50w drive). I can see 1000-1100 pep on 80/40m's with 80w's drive in WAR MODE.
I have run these now going 18 months and still with 65w drive show 700-850w pep, but I can tell my WAR MODE operation has taken a little off the top....
They are solid performers and so is the amp.

I am hoping to finish the restoration of the DRAKE L4B, I having been working on for couple months...maybe 6 or 8 hours more hours work till I test her.
She has the new Harbach soft start and soft key modules already built and installed, new T/R relay and a cleaned up blower assembly and chassis.
I am working on the PS. This will have the Harbach upgrade B+ board installed(already assembled) and all the old TW insulation type wiring(75deg C) replaced with THHN (105deg C) insulation wiring.
Then the final addition of a NEW Matched set of Amperex PR 3-500ZG fire bottles.
Well enough said!
All the Best
BJ
 

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