[Amps] tetrode push-pull amp schematics

[Gary Schafer]

Push pull doesn't really buy you anything other than reduced 2nd harmonics,
which isn't a problem as the tank circuit will take care of that for ham
purposes.
It is sometimes used on higher frequencies if the plate capacitance of the
tube is very high and it is a problem getting the tank circuit Q right. Push
pull allows for a lower capacitance plate tuning capacitor.
But on HF you don't have that problem with that tube.

Push pull tubes will not reduce intermodulation products. 
You do not want to run a 4CX1500 in anything but AB1 or class A. normal
operation of that tube in AB1 is close to class A anyway.

All you buy with push pull is more complicated circuitry for no practical
reason.
If you just want to be able to say "I did it" then that's another story.

73
Gary  K4FMX

> -----Original Message-----
> From: Charlie [mailto:charlie at drhabekost.com]
> Sent: Wednesday, June 17, 2015 9:32 PM
> To: 'Gary Schafer'
> Subject: RE: [Amps] tetrode push-pull amp schematics
> 
> Gary-
> 
> Looking for a slight bit more power than a single 4cx1500; was making a
> 4cx5000. Too much, and the tube will not fit in my desktop cabinet.
> 
> Like the idea of push pull, possible increase in linearity. If done
> really
> well.
> 
> Never one to take the easy way, I like the challenge.
> 
> Charlie N6CFH
> 
> -----Original Message-----
> From: Gary Schafer [mailto:garyschafer at largeriver.net]
> Sent: Wednesday, June 17, 2015 6:48 PM
> To: 'Brad Osburn'; 'Charlie'; amps at contesting.com
> Subject: RE: [Amps] tetrode push-pull amp schematics
> 
> Why would you want to build a push pull amplifier?
> Single ended is much simpler.
> 
> 73
> Gary  K4FMX
> 
> > -----Original Message-----
> > From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Brad
> Osburn
> > Sent: Wednesday, June 17, 2015 5:21 PM
> > To: Charlie; amps at 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 at 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
> > _______________________________________________
> > Amps mailing list
> > Amps at contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
> > _______________________________________________
> > Amps mailing list
> > Amps at contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>