Re: [Amps] Why 2 3CX800s instead of one 8877?

[Alek Petkovic <vk6apk@bigpond.com>]

Ha. That's what ya call "thinkin' outside the anode."

Cheers, Alek.
VK6APK

On 26/04/2019 5:40 AM, Carl wrote:
> Since a pair of 3CX800's wont even come close to running hard in a 2 
> or 3 hole 76A series amp then a little careful surgery will do the trick.
> Remove enough of the anode cooler from both tubes so that they will 
> fit with about 1/4" spacing.
> Dont laugh, it is just a part of hams doing what works when needed.
> I modified several 8874's decades ago to replace the 8873 in Heath 
> SB-230 amps. At that time they were cheap as full power medical and 
> other pulls.
> My own SB-230 modified for 6M and used for portable and roving has 
> been fine since 1985.
> Carl
>
>
>
> ----- Original Message ----- From: "Colin Lamb" <k7fm@teleport.com>
> To: "Mike McCarthy,W1NR" <lists@w1nr.net>; "Roger (K8RI)" 
> <k8ri@rogerhalstead.com>; <amps@contesting.com>
> Sent: Tuesday, April 23, 2019 8:19 PM
> Subject: Re: [Amps] Why 2 3CX800s instead of one 8877?
>
>
> > I am somewhat mystified by the messages.  The Alpha 76A has 2 or 3 
> > tubes 3CX400.  But there is a difference.  The 3 tube version you can 
> > plug one socket and then use 2 3CX800A7 tubes.  They fit fine.  I 
> > changed one and mounted the transformer inside the unit.  It works fine.
> > There is a problem with the two tube version.  If you change to tubes 
> > to 2 3CX800 tubes - the sockets are too close together so they do not 
> > fit. That would require more work because the holes and all the 
> > chimenys are too close together.  I have a 2 hole amp and used the 
> > 3CX400 tubes.  I run that amp at 1200 watts and it has run flawlessly 
> > for years.
> > I did a couple of other things to my amp.  I installed a vertical 
> > array inside between two meters for grid response.  Because these 
> > LEDs are much quicker that the meter it is much faster and that lets 
> > me monitor forward output with the meter.  Then, I converted the 
> > output meter to read peak reading with a meter used for the Bird 
> > Wattmeter.  I have about 6 amplifiers and with those two changes this 
> > amp is the one I use day after day.
> > 73,  Colin  K7FM
> > _______________________________________________
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> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps 
>
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