Re: [Amps] tetrode push-pull amp schematics

["Jeff AC0C" <keepwalking188@ac0c.com>]

I'm not sure the gentlemen's value assessment on the amps various attributes 
(other than the focus on clean) - but there is definitely merit to having 
done something uncommon - just for the sake of doing it.  "I've got a home 
brew push-pull pair here" makes a very nice discussion topic in a rag chew.
73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-----Original Message----- 
From: Vic Rosenthal
Sent: Thursday, June 18, 2015 1:45 AM
To: <amps@contesting.com>
Subject: Re: [Amps] tetrode push-pull amp schematics

The 4CX1500b is designed to be exceptionally clean in class AB1. I don't 
know if anything significant is to be gained by operating class A as a 
previous poster suggested. Unless you need a shack heater!
I also don't understand why push-pull is so attractive.
The easiest way to get an unbalanced output is to use link coupling as shown 
in the old handbooks. You can use a fixed link with a series capacitor as a 
loading control.
Vic 4X6GP/K2VCO

> On Jun 18, 2015, at 4:26 AM, Charlie <charlie@drhabekost.com> wrote:
>
> 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:
> http://www.pmillett.com/tubebooks/technical_books_online.htm
> 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 [mailto:plantrunner5@msn.com]
> Sent: Wednesday, June 17, 2015 3:21 PM
> To: Charlie; amps@contesting.com
> Subject: Re: [Amps] tetrode push-pull amp schematics
>
> Charlie,
> 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.
>
> Brad
> AB0YD
>
> -----Original Message----- 
> From: Charlie
> Sent: Wednesday, June 17, 2015 12:41 PM
> To: amps@contesting.com
> Subject: [Amps] tetrode push-pull amp schematics
>
> I am looking for a schematic of a push pull tetrode amp. Any ideas?
>
> Thanks,
>
> Charlie
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