Re: [Amps] HB amps

["Bill L. Fuqua" <wlfuqu00@uky.edu>]

I don't think plate dissipation is the what limits the 813, but emission. A 
pair of  carbon plate 813's have much more surface area than a single 3-500. It 
takes a lot to make them glow. Their plate dissipation is very under rated. 
According to the Radio Handbook in GG and 2500 volts V+ will produce 350 watts 
per tube with only 11 watts drive.  Also the 3rd order IM distortion -33 dB.  
So 4 tubes could produce a full gallon with only 44 watts drive.
Not bad.  Only about half of the 813's that I have purchased  used have good 
output. I suspect that many were abused in their earlier life. 

73
Bill wa4lav

  
      

-----Original Message-----
From: "Will Matney" <craxd1@verizon.net>
To: amps@contesting.com
Date: Fri, 03 Mar 2006 16:43:11 -0500
Subject: Re: [Amps] HB amps

My guess G-G for 600. I was thinking myself of building one of these with 813's 
since they're still making them. Shugang Tubes in China is making them and the 
811 I believe. I have a design I had started on for using (4) 813's running 
grid driven or G-C that I never did finish.

Best,

Will

*********** REPLY SEPARATOR  ***********

On 3/3/06 at 9:36 PM Mike Bondarev wrote:

>Hi Gary!
>
>> A pair of 813's will easily produce 600 watts output and do it for years
>and
>> years. They are very rugged tubes. I have an amp with a pair of them
>that I
>> built in the mid 60's and it still has the same pair of tubes. At one
>time I
>> ran them with over 3000 volts on the plates for several years with the
>> plates regularly showing color and power out well above 600 watts.
>> The same tubes now run at around 2500 volts and still put out 600 watts
>and
>> no color.
>
>> Not the best tube in the world but for the price and as rugged as they
>are
>> they are hard to beat.
>> They will perform well on a wide range of voltages too. 2000 to 3000
>volts.
>
>> 73
>> Gary  K4FMX
>
>
>Is it GG or GC ?
>
>Regards, Mike RL3BM
>
>
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