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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: Pete Smith N4ZR <pete.n4zr@gmail.com>
Date: Sun, 22 Jan 2023 11:43:07 -0500
List-post: <mailto:cq-contest@contesting.com>
And this is, of course true.  Reciprocity is just a starting point.  Yesterday in NAQPSSB I had an S9 noise level on 20-10 meters, where I also have directivity.  I had a hard time hearing anyone in the direction of the noise, but putting it at 90 degrees let me work at least a few.

73, Pete N4ZR

On 1/22/2023 10:26 AM, K9MA wrote:
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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