[Boatanchors] 4-400 tube replacing a 3-400z for circuit test

[david freeman]

The screen was grounded along with the grid.
All the grid pins were grounded in my amp, I didn't have to modify anything.
My brother told me he ran an Amp Supply with 4-400s for awhile with no ill effects.
I probably wouldn't have tried it otherwise.

73, Dave, WW8S


> ----- Original Message -----
> From: "Richard W. Solomon" <w1ksz at earthlink.net>
> To: "david freeman" <_dave.f at mail.com>, "Greg Mijal" <bluebirdtele at earthlink.net>
> Subject: RE: [Boatanchors] 4-400 tube replacing a 3-400z for circuit test
> Date: Thu, 14 Dec 2006 20:54:14 -0500
> 
> 
> What do you do with that extra grid ??
> 
> 73, Dick, W1KSZ
> 
> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net
> [mailto:boatanchors-bounces at mailman.qth.net]On Behalf Of david freeman
> Sent: Thursday, December 14, 2006 8:30 PM
> To: Greg Mijal
> Cc: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] 4-400 tube replacing a 3-400z for circuit
> test
> 
> 
> I've used 4-400 in place of 3-500 and it works, sort of.
> The input impedance is different and it messes up the tuned input.
> My amp didn't have enough input adjustment to compensate.
> That's assuming that the Swan has tuned inputs, but I'm not familiar with
> it.
> If you have a transceiver with a tuner built in that should help matters.
> I don't remember exactly, but after adjusting, the SWR was high, but not
> ridiculous.
> I, like you, was only interested in testing things out, not operating that
> way.
> 
> 
> YMMV
> Dave, WW8S
> 
> > ----- Original Message -----
> > From: "Greg Mijal" <bluebirdtele at earthlink.net>
> > To: boatanchors at mailman.qth.net
> > Subject: [Boatanchors] 4-400 tube replacing a 3-400z for circuit test
> > Date: Thu, 14 Dec 2006 16:12:29 -0700
> >
> >
> > Hi:
> >
> > Has anyone used 4-400's in a made for 3-400Z's amplifier?
> > I have a Swan MK 1 amplifier built for two 3-400Z's and no tubes.
> > I do have a set of 4-400's.  The necessity of this is to evaluate
> > the amplifier overall circuit, not necessarily "Convert" the amp.
> > Anyone do this one before?
> > Thanks
> > Greg
> > WA7LYO
> > in sunny Feenix
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> 
> >
> 
> 
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