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

["Roger (K8RI)" <k8ri@rogerhalstead.com>]

Why not just punch another hole?

73, Roger (K8RI)

On 4/26/2019 6:36 PM, Alek Petkovic wrote:
> 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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> >
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--
Roger (K8RI)


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