Hardy,
I'm also driving an old Alpha but don't
know how similar our amplifier input
circuitry is. I too have a K3 with
internal tuner. I have no aftermarket
tuner in line and at the antenna end, have
5 vertical antennas all switched via a
remote Ameritron RCS-8V.
If I run barefoot, the SWR to the K3 is
different than if I go through the amp. I
must first use auto-tune on each band with
each antenna I switch to. The memory in
the K3 retains all SWR settings and I
never have to re-adjust until I once again
use (or turn off) the amp. This change
means I have to use auto-tune again but
after doing this, I'm fine again. Your K3
should be the same. If I do not use the
auto-tune after making a change, I will
get fold-back issues, with terrible output
and it just isn't graceful.
73,
Gary
KA1J
> My K3 has a real problem driving the 8410. Even with the matching network it
> has a problem I can't seem to understand.
> The SWR on 12 m is over 3:1.
> Hardy N7RT
>
> ----- Original Message -----
> From: "Peter Voelpel" <dj7ww@t-online.de>
> To: <amps@contesting.com>
> Sent: Friday, January 09, 2015 7:26 PM
> Subject: Re: [Amps] Alpha Input SWR
>
>
> > What is bad about SWR <2?
> >
> > 73
> > Peter
> >
> > -----Original Message-----
> > From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Hardy
> > Landskov
> > Sent: Samstag, 10. Januar 2015 03:09
> > To: Charles Henry; ed@w0yk.com; amps@contesting.com
> > Subject: Re: [Amps] Alpha Input SWR
> >
> > Charly,
> > Changing the length of coax to the input will not change the SWR. Look at
> > a
> > Smith Chart. Only dealing with the tube's capacitance along with the 50
> > ohm
> >
> > resistor to ground with a suitable matching network will lower the input
> > SWR. I wish Alpha and whoever is the designer of amps now would match the
> > input to every band but they don't. It's not that much more money to do it
> > right.
> > I am going to sell this 8410 because of that reason. What a piece of junk.
> > 73 HNY to all.... Hardy N7RT
> >
> > ----- Original Message -----
> > From: "Charles Henry" <k4vud@hotmail.com>
> > To: <ed@w0yk.com>; <amps@contesting.com>
> > Sent: Friday, January 09, 2015 3:15 PM
> > Subject: Re: [Amps] Alpha Input SWR
> >
> >
> >> All I have been able to do is to cut and try the length of the drive coax
> >> from the radio RF output to the amplifier input.
> >> Sri forgot the lengths and never got 1:1 anyway. Charly
> >>
> >>> From: ed@w0yk.com
> >>> To: amps@contesting.com
> >>> Date: Fri, 9 Jan 2015 08:44:18 -0800
> >>> Subject: [Amps] Alpha Input SWR
> >>>
> >>> What experience can anyone share for reducing the input SWR on Alpha
> >>> amps?
> >>> On some bands the input SWR is 1.6:1 or higher on our 86A, 87A and 91B
> >>> amps.
> >>>
> >>> Thanks,
> >>> Ed W0YK
> >>>
> >>> _______________________________________________
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> >>> Amps@contesting.com
> >>> http://lists.contesting.com/mailman/listinfo/amps
> >>
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> >
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> >
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>
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