A friend of mine came up with a cooling mod for the 811H.  He added a second
fan to the left side of the amp, covered the holes on the left side of the
cabinet, and drilled a new set of cooling holes on the top, right over the 4
tubes.  He totally changed the direction of flow, but now the amp stay just
about at room temperature.  Hardly even warm to the touch.  He did a super
job making it look like it had always been that way from the factory.

Alan/KD7GC


Alan R. Downing
Phoenix, AZ


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Tom Behler
Sent: Sunday, April 27, 2014 7:00 PM
To: [log in to unmask]
Subject: Re: Al-811H

Agreed, Alan.

Your overall approach with the AL811H sounds quite similar to mine.

Tom Behler: KB8TYJ


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Alan R. Downing
Sent: Sunday, April 27, 2014 9:19 PM
To: [log in to unmask]
Subject: Re: Al-811H

Tom, I generally drive the AL811H with about 50 watts.  I know that I could
easily get another 100 watts out of it, but to what purpose?  I recently
replaced the 4 811A's, and my output increased by 50 watts or so, but I
simply don't push it hard.  If I used it on 20 say, then I would probably
push it to the max, but on 10 meters, it simply isn't necessary.

Alan/KD7GC



Alan R. Downing
Phoenix, AZ

-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Tom Behler
Sent: Sunday, April 27, 2014 5:03 PM
To: [log in to unmask]
Subject: Re: Al-811H

Alan:

Your readings seem similar to those that I get with my AL811H here at the
home QTH, in conjunction with my TS590.

How much power do you drive your amp with?

I tend to drive mine with between 50 and 60 watts.

I prefer to do that, rather than pushing the envelope too far.

Tom Behler: KB8TYJ


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Alan R. Downing
Sent: Sunday, April 27, 2014 8:01 PM
To: [log in to unmask]
Subject: Re: Al-811H

Phil, I have an AL811H here, and I typically get about 600 watts out of it.
I could push it harder than I do, but I don't think that it is necessary to
do so.  I often leave it tuned up on 10 meters, and when ten is open, 600
watts is plenty.

Alan/KD7GC



Alan R. Downing
Phoenix, AZ


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Phil Scovell
Sent: Sunday, April 27, 2014 5:04 PM
To: [log in to unmask]
Subject: Al-811H

Mike,

It's been awhile since I read about the 811H so can you tell me how much
power you can get out of it and with how much drive?

Phil.
K0NX



----- Original Message -----
From: "Michael Ryan" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, April 27, 2014 5:12 PM
Subject: Hopefully this fixes things


> Hey all:
>
> Just ordered a new set of tubes and a new parasitic board for my AL-811H.
> Hopefully I will get it back up and running in a couple of weeks as 
> I've missed it, the last couple of weekends when operating.
> After I had the friend take a look at solving my reduced 20M output, 
> the amp kind of unravelled a little. The parasitic board blew and the 
> tubes failed.
> Well, one of the 4 failed and rather then replace just one, I ordered 
> a match set.
>
> 73:
> Mike VO1AX
>