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Re: [CQ-Contest] Reciprocity in signal strength

To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] Reciprocity in signal strength
From: K9MA <k9ma@sdellington.us>
Date: Sun, 22 Jan 2023 09:26:26 -0600
List-post: <mailto:cq-contest@contesting.com>
That's true, but only part of the story. On the HF bands, receiver noise is almost always negligible, so absolute signal strength doesn't matter much. If your random wire isn't matched, all bets are off. Even modern radios have drastically different S-meter calibrations: 3 or 6 dB per S-unit. You may also have various lossy components in the received signal path. Noise levels also vary enormously, so even at the same absolute signal strength, S/N can be very different. And then, of course, there's QRM and competition.

73,
Scott K9MA

On 1/22/2023 12:10 AM, Barry Jacobson wrote:
Hi guys, it seems that in a contest like NAQP where presumably almost
everyone is running the same 100 W power, you should be able to hear the
other guy at the same level he hears you. Even if the other guy has a
$25,000 dollar beam, and you have a simple 10 foot random wire, the
weakness in your transmission ability will also weaken your received signal
just as much in the other direction. So if you can hear him, it guarantees
he can hear you. (Unless one or both of you has separate receive and
transmit antennas, or the receivers you are using are of very different
quality.) Does that make any sense?

Barry WA2VIU

--
Barry Jacobson
WA2VIU
bdj@alum.mit.edu
@bdj_phd
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--
Scott  K9MA

k9ma@sdellington.us
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