Posted by
Dave Perry N4QS on
Jan 18, 2012; 1:00am
URL: http://elecraft.85.s1.nabble.com/KPA500-another-view-tp7198413p7198692.html
I think that for serious Dxers, 6 db can make a huge difference. I have a
KPA500 and a KW amp. I tend to use the 500 watt amp for casual contesting
and Dxing. But I find that I often have to turn on the KW when I am working
very weak signal DX or when I am trying to bust a big pileup. For example,
I have an inverted L on 160M (and have worked 99 countries over the last
three winters on top band). I am finding this winter that when an EU
station can't hear me with the KPA500, the station often comes right back
when I turn on the KW amp. The same goes if I am attempting to work a weak
Asian sig on the higher bands. In short, when you are dealing with weak
sigs just barely audible above the noise threshold, 6 db makes a big
difference! You need that 6 db even more when you live in western KY!
Dave, N4QS
-----Original Message-----
From:
[hidden email]
[mailto:
[hidden email]]On Behalf Of Alan Bloom
Sent: Tuesday, January 17, 2012 6:30 PM
To: Vic K2VCO
Cc:
[hidden email]
Subject: Re: [Elecraft] KPA500 (another view)
Very true. But even 6 dB would not make a big difference for a
rag-chewer or a casual contester. Even for a fairly serious DXer, being
in the right place at the right time and having superior operating
skills are more important than an S-unit of signal strength.
The place where the best possible signal is really essential is for a
world-class contest station. Those guys agonize over every fraction of
a dB of feedline loss.
Alan N1AL
On Tue, 2012-01-17 at 16:20 -0800, Vic K2VCO wrote:
> Keep in mind that it all adds up. If you get 2 db more from your beam, and
3 db from going
> from 500 to 1000 watts (say), and maybe a db by replacing your old coax,
etc., that's 6 db
> -- a huge advantage.
>
> On 1/17/2012 4:15 PM, Alan Bloom wrote:
> > Interesting experiment Dave. I think that kind of test is valid for VHF
> > operation. But on HF it is very rare to hear a signal at a constant
> > level like that.
> >
> > Normally signal strength varies considerably from moment to moment due
> > to fading. Even if the average signal level is right at the noise
> > level, most of the time it will be well above or well below that level.
> > A dB or two increase or decrease will vary the percentage of time the
> > signal is copyable, but only a little. The QRM also varies in signal
> > strength from moment to moment.
> >
> > Of course, louder is always better. But unless you are a big-gun
> > contester, where winning or losing depends on a few extra contacts over
> > the course of the weekend, I think you'd have a hard time noticing a
> > couple dB difference in normal operation.
> >
> > I am just about to order a 2-element SteppIR Yagi. I decided that the
> > extra dB or two of the 3-element model is not worth another $450. :=)
> >
> > Alan N1AL
> >
> >
> > On Tue, 2012-01-17 at 16:52 -0700, David Gilbert wrote:
> >> A power ratio of 3 (1500 watts versus 500 watts) is just under 5 db.
> >> Check out these audio files (CW, though ... not SSB) I generated to see
> >> what kind of impact that can have for readability of signals near the
> >> noise threshold.
> >>
> >>
http://www.ab7e.com/weak_signal/mdd.html> >>
> >> 73,
> >> Dave AB7E
> >>
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