To help Fred out further, I ordered my matched quod of 572B's from RF 
parts.

I believe the web site is:

www.rfparts.com

The matched quod (set of four) was $199, which is about $100 more than a 
matched set of 811's, but, in my view, the more robust tubes are worth the 
extra cost in the long run.

73 from Tom Behler:  KB8TYJ

----- Original Message ----- 
From: "Kevin Nathan" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, August 13, 2010 6:10 PM
Subject: Re: Tube amplifiers


Hi Fred,

They are very common but, as John says, they are a little more expensive.

Very 73.



Kevin :)
Amateur Radio:  K7RX


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Fred Adams
Sent: Friday, August 13, 2010 14:33
To: [log in to unmask]
Subject: Re: Tube amplifiers

Are 572B tubes easy or hard to find?  Thanks to you guys for the info on the

811 tubes.  I'll hold on to this info for future reference.
----- Original Message ----- 
From: "John Miller" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, August 13, 2010 1:02 PM
Subject: Re: Tube amplifiers


> I've used an amp with 811 tubes with no problem. My recommendation though
> is
> swap the 811 tubes with 572B's which run cooler but I can't complain about
> them I don't know why they'd be any harder or easier than anything else.
> ----- Original Message ----- 
> From: "Fred Adams" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, August 13, 2010 11:46 AM
> Subject: Tube amplifiers
>
>
>> Are any of you guys using or have you used an amplifier with 811 tubes?
>> I
>> have heard some blind hams say that amplifiers with 811 tubes are not
>> very
>> easy to tune, what do you think?  I was thinking of getting one or a
>> single
>> 3-500 tube amplifier.  I would appreciate your comments.  I purchased a
>> new
>> Ameritron AL80B several years ago and didn't like it so I swapped it off.
>>
>>
>>
>> Best wishes,
>>
>>
>> FRED ADAMS W4HC
>> LETS ALL REMEMBER
>> VOTE IN NOVEMBER