Ameritron Pre Purchase Tech Questions

[NightOwl3261]

Which Ameritron would be best suited with 10 meter mod if one is looking to keep PEP at no more than 400 watts SSB use only. Looking at new 811 or 811H new vs AL-80B used. Long.Life and low failure is a concern. Can one get a AL-80B down to 500watts pep on 10m with reduced drive from radio? So many models and so much to consider. Your help and advice would be appreciated. If possible what drive with each model gets 500 watts out with 10 meter mod. Also is the AL-80B Just a green will clip and input tune for 10 meters like the 811's? Got a line on a clean AL-80B but need to know I can run it at 500 pep with reduced radio drive to keep within the limits of my tuner, antenna etc.
Your help with knowledge of ameritron amplifiers would be greatly appreciated before I make a purchase.

 

[nomadradio]

Green wire. Roger. Same on all Ameritron amplifiers from the factory AFAIK.

I have nothing good to say about the 811A linears. A single 3-500Z is just more durable and forgiving of 'oops' moments.

Reduce the drive, and make sure the Load control is peaked for the drive level you use. You can't "under drive" the amplifier. Just tune it for the drive level you will use.

The Load control's peak setting will change with the drive level. The amplifier is most efficient when that control is peaked for the power level you'll use.

73

 

[Justme]

i run the Heathkit SB-1000 the buiding project from Heathkit AL80 amp.
Replaced the 3-500 for a 3-500 ZG and rebuild the amplifier 8 years back, mostly running between 500 to 700 watts out reduced drive if you do that and know how to tune the amp it will last you a lifetime.
I'm running it from 160 to 10 meters, easy tune, works as it should, with the rebuild and new parts it will outlast me.

 

[Dmans]

I have nothing good to say about the 811A linears.

+1

The 811A amps are good for the repairman, bad for the owner!

73
David

 

[NightOwl3261]

Good to know that I should stay away from 811 tube amplifiers. Buy the way why the high failure rate on the 811a Amplifiers?

 

[NightOwl3261]

Many of the AL-80B amplifies for sale had been manufactured in the 1990's. Seems to be to much of a risk unless they have been gone over, caps replaced etc. Am I correct? Is it a big risk if it that old without of history of being gone through?

 

[BJ radionut]

My Ameritron Amplifier was built in 1994...still working as original...time for some updates IMHO...but otherwise just fine!

PS: DRAKE L4B SS #79 ... built in 1968 ...Harbach upgrade PS board /bias control added 10 years ago ... still with same tubes as purchased, 1200W+ ...
Also should note: Paid $600 w/tubes Harbach upgrades add $300 max spent...Pretty good service for old girl...
Willing to do the work, you can get excellent service for most well-made Amateur Amplifiers regardless of age.
I have BTI-LK2000 amp built in 1966...did updates myself almost 20 years ago... still near full legal limit

 

[NightOwl3261]

My Ameritron Amplifier was built in 1994...still working as original...time for some updates IMHO...but otherwise just fine!

PS: DRAKE L4B SS #79 ... built in 1968 ...Harbach upgrade PS board /bias control added 10 years ago ... still with same tubes as purchased, 1200W+ ...

What model Ameritron?

 

[BJ radionut]

What model Ameritron?

AL811
I keep it around because it does 160m, where my Drake and other tubes amps do not. Nice 500 watts plus with about 50 watts drive

The AL80 A/B is a FINE Amplifier!!!!
Run amp @ 6-700 watts PEP will last a lifetime
(That is only one half an "S" unit below Full Legal Limit!!!)

Likewise, the AL82 is a brute!

 

[YR Mason FL]

I do not have an 811 amp but I wouldn't ignore a good offer on one in good condition.

I have the Ameritron ALS-600 SS Amp. I needed some work done on it and decided to send it to the man that played a major part of the designs of the Amertron Amps Tom W8JI (before a lot of the sloppy assembly took hold). I hear that the earlier 90's Ameritron tube amps have held up very well over the years

Tom Rauch W8JI services these amps and some others through his company CTR Engineering in Barnesville Georgia and he made my 600 work flawlessly at peak performance. MFJ is so backlogged on both service and new Amps right now you could wait up to 6 months or so. Tom was much faster and more thorough in his repairs & I highly recommend him. He has an Ameritron FB Page where you can post and ask questions to him. He designed them so I take his word on them. Tom also has a huge information webpage on all sorts of Amateur and Communications-related items... I believe it is w8ji.com (he's not trying to sell anything there it is for technical information)

I hear a lot of people replacing the 811 tubes with 572B, although they do not actually guarantee any better output they can be a little more forgiving than the 811's but good luck finding any tubes comparable to the quality tubes of the good old days.

One thing that I don't like about the ALS-600 is that it does not cover 6 meters but it was what I could afford at the time. I have no issues with working with anyone that I can hear on any of the other bands so I am good with that.

 

[NightOwl3261]

I do not have an 811 amp but I wouldn't ignore a good offer on one in good condition.

I have the Ameritron ALS-600 SS Amp. I needed some work done on it and decided to send it to the man that played a major part of the designs of the Amertron Amps Tom W8JI (before a lot of the sloppy assembly took hold). I hear that the earlier 90's Ameritron tube amps have held up very well over the years

Tom Rauch W8JI services these amps and some others through his company CTR Engineering in Barnesville Georgia and he made my 600 work flawlessly at peak performance. MFJ is so backlogged on both service and new Amps right now you could wait up to 6 months or so. Tom was much faster and more thorough in his repairs & I highly recommend him. He has an Ameritron FB Page where you can post and ask questions to him. He designed them so I take his word on them. Tom also has a huge information webpage on all sorts of Amateur and Communications-related items... I believe it is w8ji.com (he's not trying to sell anything there it is for technical information)

I hear a lot of people replacing the 811 tubes with 572B, although they do not actually guarantee any better output they can be a little more forgiving than the 811's but good luck finding any tubes comparable to the quality tubes of the good old days.

One thing that I don't like about the ALS-600 is that it does not cover 6 meters but it was what I could afford at the time. I have no issues with working with anyone that I can hear on any of the other bands so I am good with that.

How pricey was his repairs. Sometimes repairs seem to equal to buying new or a quality used.

 

[nomadradio]

why the high failure rate on the 811a Amplifiers?

The tube is busting a gut at the rated 75 Watts of plate dissipation. If you run an amplifier at around 50 Watts of heat per tube, they last longer.

The tube is unforgiving about exceeding the 'red line'. Tends to suffer permanent damage before you go very far past its limits.

Larger transmitting tubes tend to have more safety margin in them to tolerate brief overloads. But not the 811A.

The bigger brother 572B has the exact, same cathode and grid. Only the anode and glass are larger. And more robust. Can't melt a hole in the graphite anode of the 572B. A round hole melted in the sheet-metal anode is a common 811A failure.

The 572B can be clobbered also. But the weak link in the chain is moved. From the anode in the 811A, to the grid in the 572B.

73

 

[YR Mason FL]

How pricey was his repairs. Sometimes repairs seem to equal to buying new or a quality used.

It was very reasonable in my opinion. I went ahead and had him replace all 4 MRF 150 FET's since he already had to replace 1.

I am not certain if we are permitted to link to websites but if you want to look him up go to his website at ctrengineeringinc.com and look under Ameritron (and other) Amplifier Repair Service and I think it lists his rates etc...

Email Tom at the "Service" email at the address in his instructions. He was fairly quick to reply when I emailed him.

 

[Dmans]

A round hole melted in the sheet-metal anode is a common 811A failure.

That has also been my experience with the 811A amplifiers.
A "meter worshipper" can go through the tubes pretty quick. It seems constant tuning and re-tuning for those extra 5 watts will kill the tubes very quickly and take out other parts in the 811A amplifiers.
I did install one of W8JI's tuning modules in one of the amps I repaired but it seems to only extend the life of the 811A's marginally.
I have recommended to the owner of this amplifier to replace the 811A's with 572's but so far he has been hesitant. I am pretty sure this amplifier will be returning to me again as soon as I complete the refurb on his SB-220.

73
David

 

[Shockwave]

If you are relying on reducing the drive and having the radios ALC circuit clamp the amplifier output to a safe limit for your tuner, you may arc over the air variables on word peaks. That can be caused by brief periods of ALC overshoot on your word peaks. The scope would reveal the potential of this overshoot prior to any arc. Your ear will let you know as it's happening.