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Re: [Amps] tetrode push-pull amp schematics

To: "'Brad Osburn'" <>
Subject: Re: [Amps] tetrode push-pull amp schematics
From: "Charlie" <>
Date: Wed, 17 Jun 2015 18:26:49 -0700
List-post: <">>
Brad et al-

Thanks for the replies. Lessons learned:
1) A Startpage search is not a Google search!!!
2) This book link is a goldmine:
3) I still am vague on converting the balanced output shown on the "older"
schematics to unbalanced 50 ohm contemporary design. 

Any further ideas along these lines? I too am thinking of a push/pull
4cx1500 amp, Brad. I am looking for exceptional linearity.

Charlie N6CFH

-----Original Message-----
From: Brad Osburn [] 
Sent: Wednesday, June 17, 2015 3:21 PM
To: Charlie;
Subject: Re: [Amps] tetrode push-pull amp schematics

Under the heading of For What it's Worth

I too am building a push-pull amp (4CX1500B). Basically I'm using Rich's 
single ended broadband input (4:1 balun xfmr terminated in 200 ohms, 100 
either side).  Which I have completed and according to my impedance meter, 
looks good.  I don't care about power just want a clean signal, so I'm 
thinking of running class A.  I'm down to the tank circuit and I think I'm 
going to have a balanced output into my horizontal loop antenna, (600 ohm 
ladder line input)  thru a 4:1 balun. For a screen supply I'm again using 
Rich's zener string off of the plate supply.  Generates a whole bunch of 
heat thru the dropping resistor, but I think it should prove to be pretty 
full proof.
May incorporate the 4:1 balun in my tank circuit by going to a 200 ohm 
output, as I said I'm still designing. Found quite a few designs in the 1949

Handbook. I built Rich's balanced tuner and it works well, may incorporate 
that in my output as well.

This is my first amp I've designed so I'm just trying for 160-80-40.  Using 
a 2400 volt control transformer (5kva) for my supply and I took 5VDC linear 
supplies and redid the control board to give me the 6V+- out I need for 
filaments and so I have a regulated filament supply.  Limit inrush to less 
than 2X.

For the record Rich said don't do it (band switching). But I've wanted to do

this since HS.


-----Original Message----- 
From: Charlie
Sent: Wednesday, June 17, 2015 12:41 PM
Subject: [Amps] tetrode push-pull amp schematics

I am looking for a schematic of a push pull tetrode amp. Any ideas?


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