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  #1  
Old 01-05-2008, 03:39 PM
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Default Homebrew amplifier

Started a new amplifier project.
More of a clone. It will be cloned after the AL-811h.

It will contain 4 811a's
I decided to go with this design because parts are still avalable.

Building the chassis.
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Old 04-07-2008, 02:10 PM
G4LNA G4LNA is offline
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Hi Buddy,

How far have you got with your amp? I noticed you posted those piccys back in January, so I should think you should be somewhere down the line now. Will the PSU be separate or is it built in?

I built myself an amp which I've been using for about a year now, it uses a pair of 4CX250B tubes in the output. It will push out about 600 Watts which exceeds our 400 Watt limit we are allowed to run over here.
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Old 04-07-2008, 08:01 PM
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Hi and thanks for the notice.
I had started gathering parts for this about a week before posting the pics.
The case is 13 by 17 inches, and should be able to hold the power supply with no problems.

Most of the parts are just sitting on the table. No way down the line I should be on this project. About a month after starting I changed positions at work (temporary thing) . In the last month I have not even been able to spend any time in the shack. Last week I went to another position (permanent) so things are slowing down quite a bit. This past weekend was the first in a while to even get out to the shack.

The amp is based off of the Ameritron 811. I hope to achieve around 600 to 800 watts out of it. Planning on working on it a bit this comming week end.

I will post some progress as it advances.
Also this will be my first 'Big amp" I ever have tackled. I built some smaller stuff in the past , tubes and transistors.
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Old 04-08-2008, 12:33 PM
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Yes, keep us up to date on how you progress, I take great interest in anyone building equipment like this. I hope your are able to get the necessary parts OK. That's the trouble this side of the Atlantic, getting the RF components that are able to handle the RF power. Mostly it's a case of going to rallies, even then it is getting quite difficult sometimes, to say nothing of the cost, because dealers know how much these things are worth now.

I have had to order some components from RF Parts in California, because they are not available in the UK.

I would post some of my pictures, but they are large, so I must see if I can resize them.
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Old 04-09-2008, 02:28 AM
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Nahhhh, not too big m8, especially if you do it this way.....
http://www.qsl.net/g4lna/shack_images/pa.jpg

Very nice shack you have there too Paul. A friend of mine and I, well especially him, were getting quite deep into amps, restoration and home brew. I still have a minty SB-221 that needs to be finished up. We have just had so much bad luck that we are giving our wallets a rest. Torching off brand new tubes can get deep into one's pocket in a hurry!
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Old 04-10-2008, 12:45 PM
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Thanks for posting that link Tom, not very pretty is it? Still, it works and is safe so I'll label it properly some day.

I know what you mean about the cost of new tubes, luckily I managed to get two pair of matched 4CX250B tubes for fifty quid, about $100 off Ebay, so they'll keep me going for a few years.
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Old 04-10-2008, 01:15 PM
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I thought it would be of interest to see the inside of that amplifier:
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Old 04-10-2008, 02:53 PM
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Nice Paul !

Think I will have to build a second amp also.
With my recent find (6 meter unit for 726) the 4CX tube should work.
I have an old pride DX300 amp. Thinking of tearing it down and rebuilding for 6 meters. Since the 726 provides 10 watts out on 6, this should be nice.

This does mean a complete overhaul of the pride. Basically I will use the chassis, tube and socket, blower, transformer, tuning caps, ect.
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Old 04-11-2008, 03:13 AM
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Quote:
Originally Posted by G4LNA View Post
Thanks for posting that link Tom, not very pretty is it? Still, it works and is safe so I'll label it properly some day.

I know what you mean about the cost of new tubes, luckily I managed to get two pair of matched 4CX250B tubes for fifty quid, about $100 off Ebay, so they'll keep me going for a few years.
Looks great to me Paul! Thanks for posting some bigger pictures too!
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