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Re: [TowerTalk] Mosley Antenna Question

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Mosley Antenna Question
From: Jim Lux <jimlux@earthlink.net>
Date: Fri, 20 Feb 2015 08:02:43 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 2/20/15 7:28 AM, Ed Sawyer wrote:
It seems to me quite clear as to what Mosley's strategy is.  "Make my HF amp
happy and let me crack most pileups in a reasonable amount of time and I am
a happy DXer".  That means the lowest SWR at the output of the amp for the 3
bands - period (think dummy load).  All of their trap design materials are
design to be lossy and inexpensive and to balance with the lack of matching
network at the feedpoint (again inexpensive).  The gain claims are legendary
and ridiculous to the point of the strategy being that if someone really
knows the theory - they will know this isn't real as a free space gain and
waive it off anyway.  But a good portion of the market won't know any
better, like the match, and as long as they get through to the DX will be
happy.



It might also be that the perceived advantages are not so much in forward gain, but in the "shape" of the pattern in terms of side/back lobes.

When trying to make marginal contacts, or be louder than everyone else in a pileup, a few dB might be useful. Operating technique might actually be a bigger effect. Timing (when to make the call, either during the pileup, or with respect to propagation path availability) has a huge effect.

Suppressing undesired signals might also be very useful. An antenna with good directivity and poor gain (e.g. lossy) might work really well, especially if you're in an area where that would help.

Imagine a couple scenarios:
1) You're the only ham for 1000 miles and there's no thunderstorm activity anywhere near you, etc. 2) You've got a lot of other hams around, and there's thunderstorms everywhere, particularly in the direction opposite your desired DX.

The ability to suppress the extra signals in scenario 2 might be more useful than a few dB of absolute radiated signal strength.


Lots of people claim that 0.5 dB makes a difference when you're close to the noise floor, and I believe it, and that's where skill and experience helps. BUT.. to make the QSO, you need BOTH ends of the link to work. Are you presuming that the ham on the other end is also working against a 0dB SNR and is very skilled, so that boosting your Tx power (and their received signal) by 0.5 dB makes a difference? Are they optimizing the passband of their IF, listening to SSB through a 1kHz wide signal to double the SNR over a 2kHz filter.

Or, are they receiving you with 10-15 dB SNR with a wide open receiver, because they're out in a RF quiet area, and 2 or 3 dB signal strength one way or the other makes almost no difference.


Hams focus a lot on gain and VSWR claims.. They're single numbers, so it's easy to rank performance. They're also not necessarily indicative of actual operating performance.
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