[Amps] Need for input tuning circuit

[Bill L. Fuqua]

There is grid current. That is how negative bias is generated when using a "grid leak resistor".  It is bias by grid rectification.  

Two types of clamp circuits were  used. One use the DC bias  generated by the grid rectification of the amplifier it self to turn off the clamp tube and the other rectified the RF in the  clamp circuit. 

 
73
Bill wa4lav


-----Original Message-----
From: "DF3KV" <df3kv at aol.com>
To: "Vic Rosenthal" <vic at rakefet.com>, <wlfuqu00 at uky.edu>
Date: Sat, 9 Oct 2004 22:37:45 +0200
Subject: Re: [Amps] Need for input tuning circuit


----- Original Message -----
From: "Vic Rosenthal" <vic at rakefet.com>
To: <wlfuqu00 at uky.edu>
Cc: <amps at contesting.com>; <philk5pc at tyler.net>
Sent: Saturday, October 09, 2004 8:10 PM
Subject: Re: [Amps] Need for input tuning circuit

> Years ago I built some 813 amplifiers for CW work.  I used the
standard
> clamp-tube circuit in which class-C bias is generated by the grid
current flow
> through a resistor (i.e., the bias is in effect rectified driving
voltage) and
> the clamp tube protects the tube by removing screen voltage when the
key is up.
>   This had the advantage of preserving the keying waveshape while
running the
> tubes in full class-C for efficiency.


Hi Vic,

How was full class-C maintained on the opposite cycle, when  no grid
current flows?
For full class-C the 813 has to be biased with -155V at 2250V EHT

73
Peter

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