I'd like to see the the test results of the 3cx1000a7 for
both tuned input and no tuned input. I thought the
IMD carry over was small ( considering the Q of the
tank circuit ) when not using a tuned input. As far as
using a tuned input, delivering more power to the tube
was more of an issue than reducing the small amount
of IMD. This has always been my thought on the subject,
but, I may need to be re-educated!
Regards,
Larry N5BIP
On Sun, 2004-07-25 at 01:54, Jan Erik Holm wrote:
> >
> > Friends!
> >
> > I have a couple of days got a home-built amp
> > using a 3CX1000A7 - it deliver around 1200 watts
> > out, key down - only tested it on 80 meters.
> >
> > It seems that it's built, in the seventies, with
> > input circuits from an SB-220. As I think that
> > the input impedance for a 3CX1000A7 is around
> > 50 ohms can the use of SB-220 input circuits
> > be OK? I don't have the input impedance of
> > a pair of 3-500Z's here and have not tested the
> > 3CX1000A7 with an SWR-meter between the
> > tranceiver and the amp.
> >
> 3CX1000 is about 42 ohm and 3-500Z about 115 ohm,
> so inputs for 2 x 3-500Z will work just fine, just
> would need a slight tweeking, i e will make about
> 57.5 ohm.
> >
> > I know Rich will object to this (by the way
> > your letter Thursday Rich) but how about
> > not using any input circuits?
> >
> I will also strongly object! Please do not run a
> cathode driven GG amp without input matching, we
> have enough wide signals on the bands already. It
> will degrade IMD performance very much.
> >
> > Thanks in advance for answers and 73 de
> >
> > Osten SM5DQC sm5dqc@areteadsl.se
> >
> 73 Jim SM2EKM
>
>
>
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