[CQ-Contest] 500 Watt Amp or 1500 Watt Amp

Tom W8JI w8ji at w8ji.com
Tue Jul 17 05:17:20 PDT 2012


Thanks for the great examples of how things really work!!

None of the silly nonsense that 1 dB = 100 QSO's or other junk science.

The result of this, is anyone will see, is a little bit of gain can make a 
difference in a pileup in a case of CLOSE signal levels. For nearly all-real 
world cases, it takes 2-3 dB to even be noticeable. So the penalty is 
probably only just a few QSO's over a contest for 2-3 dB ERP loss, and 
mostly then with a weaker initial signal.

If the band is full of reasonable signals with moderate to good 
signal-to-noise, even 6 dB or more won't make much change. If you are near 
noise or QRM floor, 2 dB can be night and day, and even 1 dB might be 

On 40 meters here (our best band for overall propagation to Europe), signals 
are so good at night, shutting the amp off barely makes a difference in 
contact rate. On the same band on long daylight paths, 2-3 dB is noticeable 
in rate. I'd bet in an entire contest period, score would barely change from 
500 watts to 1500, but decrease rapidly as 100 watts or less was approached.

dB change vs. contacts is a very specific effect related to S/N at the other 
end, and could never be tied to score directly in a formula.

Excellent work Dave. One of the true useful gems, if people use it 

73 Tom

----- Original Message ----- 
From: "David Gilbert" <xdavid at cis-broadband.com>
To: <cq-contest at contesting.com>
Sent: Tuesday, July 17, 2012 4:55 AM
Subject: Re: [CQ-Contest] 500 Watt Amp or 1500 Watt Amp

> Or you can judge for yourself at http://www.ab7e.com/weak_signal/mdd.html
> 73,
> Dave   AB7E
> On 7/16/2012 7:23 PM, Barry wrote:
> Go for the 1500W amp.  If you haven't seen it, watch the recent webinar
> by N6BV at the PVRC site.  Dean addresses how 1 or 2 db can make a big
> difference.
> Barry W2UP
> _______________________________________________
> CQ-Contest mailing list
> CQ-Contest at contesting.com
> http://lists.contesting.com/mailman/listinfo/cq-contest 

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