[AMRadio] WTB SB-220


Jim Candela jcandela at prodigy.net
Sun Sep 26 22:47:10 EDT 2004





Hmmm, the boys on 3878 are running 1500 watts pep plus
on USB, and there is  a 100 watt AM'er calling CQ on
3880. How much of an antenna would the AM'er need to
overcome the S/N ratio? I think Astabula Bill, W8VYZ
says it all:
 
http://www.amwindow.org/audio/mov/w8vyz.mov
 
Ever hear Bill running 100 watts? When Bill and Less
K6HQI (sk) were regulars on 14286 they had to run
heavy iron to hold the frequency. A 100 watt rig was
seldom heard whereas a 500 watt rig (that 6db again)
was often armchair copy, and sometimes often drive the
QRM away.

Regards,
Jim

RJ Mattson <rjmattson at hvi.net> wrote:
If you can't get out consistantly with a Viking II,
you need an antenna -
not an amp.
bob...w2ami
www.qrz.com/callsign/w2ami


----- Original Message ----- 
From: "Gary Blau" 
To: "Discussion of AM Radio" 
Sent: Sunday, September 26, 2004 9:22 PM
Subject: Re: [AMRadio] WTB SB-220


> I've always found more RF power, at least in
significant iterations of
> ~100watts, can make a big difference on the air in
cutting thru noise
> and band conditions. But what's more important is
full modulation.
>
> One potential benefit of running a -modified- Viking
or Ranger, etc.
> into an amp like the SB220 is you can then
concentrate on improving the
> modulation performance of the exciter xmtr. This can
in turn deliver a
> more effectively modulated signal thru the entire
system and thereby on
> the air.
> Add that to the increased power ability of running a
fully modulated
> ~400 watts carrier, and a case can be made that this
is one of the
> easiest ways to get a big AM signal on the air.
> The easiest is to use a rice box for an exciter, but
that's another fist
> fight.
>
> The Viking would have to be modified a good bit to
optimize this
> approach. The first problem being reducing the RF
output to the 10-25
> watt level that the SB220 will want to see. I've
never had a VikingII,
> so I can't say for sure, but my first thought is to
try a variable PA
> screen voltage scheme. (I did this to good effect in
my Ranger.) You'd
> probably have to remove one of the 6146's in the
Viking, and make other
> changes as well, but the idea is that not only will
you be able to vary
> the drive to the amp, but it will also give the huge
benefit of much
> higher positive peak modulation capability. Positive
peaks can easily
> go way beyond 100% as the PA now is operating well
below its peak
> dissipation point. Even if you're not a believer in
hugely asymmetrical
> 'supermodulation', having an xmtr that can easily
handle it will still
> be a big improvement over the 'stock' Viking.
>
> Loudness is where it's at to get thru on a noisy
band, but having an
> extra 100-200watts as well makes a potent combo.
>
> g
>
>
> W4AWM at aol.com wrote:
> >
> > << I am looking for a Heathkit SB-220 to run about
300 watts on AM using
the
> > Viking II to drive it. >>
> >
> > Hi,
> >
> > If you are getting the full output from the V II
into a good well
matched
> > antenna, a couple of hundred more watts is not
going to make any
significant
> > difference on the receive end and will only serve
to heat up the shack
and run up
> > your power bill.
> >
> > 73,
> >
> > John, W4AWM
>
>
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