When I listened (and I was one who reported maybe a very slight advantage to
1999.5, despite the presence of a little more local noise up there), the
beacon was very light copy in either case, down near the level of the static
crashes, and I was using a flag antenna which has just an extremely gradual
gain increase as frequency increases.
But even severely SWR-mismatched antennas should not give any advantage or
disadvantage in a signal-to-noise sense on 160m.
They may, however, give some perceived ease or difficulty in copying based
on other receiver characteristics, changes in comfortable listening volume,
or changes in ratio of received audio to random room noise. I think it's
hard for people to assess changes in signal to noise ratio if the overall
signal level changes a lot. But everyone's antenna limits on external noise
on 160m.
So if you have a step attenuator, you could knock down the signal level on
the matched frequency so that it closely matched that on the mismatched
frequency and you would probably do OK. In my case, the overall signal
level is awfully flat across 160, and I would expect for the purposes of
this kind of test, anyone using a flag, pennant, EWE, or Beverage to listen
would find the same thing.
Any extraneous changes probably greatly diminish our ability to critically
listen to the different signal to noise levels, even if actual S/N ratio
isn't changing.... so it's certainly a discussion worth having. Honestly,
the best way to do this is probably to set up the beacon to transmit
simultaneously on both frequencies, and listen in stereo with practically
identical receivers fed by practically identical receivers, and to swap ears
occasionally. That way you don't have to rely on memory of how the beacon
sounded before, you'd just pay attention to which direction the beacon was
coming from in your stereo sound field.
Unfortunately I'm not set up for that, and I doubt it would be
straightforward for Tree to set up simultaneous transmitters without other
issues.
Plus, the fact that I feel like I'd only really be sure of the difference if
I did that does suggest that maybe trying to move all DX activity up to the
top end of the band would be more trouble than it's worth :-)
I'm curious for reasons that have little to nothing to do with DX though.
Just buying an amplifier and building some better RX antennas will increase
my DXCC count way faster than 2MHz vs. 1.8MHz propagation ever could.
I'm just curious about the propagation independent of whether it's useful.
73
Dan
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|