'corse, from this "troublemaker", on VHF, (and granted, the noise figure
of a reciever , or preamp is less compromised by swr, THE FURTHER from
the SOURCE(antenna), because of the loss's in that line (great dummy
load for 432: 200 foot of rg-58u, don't even terminate it! If a Bird
reads ANY swr,meter has a problem (because of the loss)! But, then look
at the loss's from the standpoint of a (Scatter, Moonbounce, Long
Distance VHF (ect)) Operator, trying for the "HOLY GRAIL" of a
BI-DIRECTIONAL 20 + dB gain, noise figure of less than , say 1.3 dB (sky
noise), and a KW ,+ Minimum FEED LOSS'S, on 2 meters to hear your own
echos. When at THAT point, and keep in mind:
1) that when stacking antennas, the MAXIMUM (maybe you know different)
GAIN accomplished on a bay, is 3 dB , for 2 antennas, 6dB, for 4
antennas,ect., 2) that The Reciever front end, Maximized for BEST NOISE
FIGURE, is adjusted to the that point, by intentionally MISADJUSTING the
front end impedence, to obtain THAT optimum point,at 50 OHMS!
and 3) that anything that is misadjusted, to add ANY LOSS's to the
system means the difference (because bad stacking distances, mis- fed
coax(out of phase), change in the front end impedence of the LNA, ect.)
means the difference between sucess,or failure!! Perhaps was wrong on
initial assumption that swr was bi-directional, but doesn't negate the
original premise that the swr has no effect on recieve-- and, btw, will
the stacking actually provide THAT 3dB?? (before, or after the added 3:1
mismatch)?? Yours for comment?? Jim NN7K


Richard Clark wrote:
On Sun, 15 Aug 2004 23:57:02 GMT, "Jerry Martes"
wrote:


It is my understanding that the transmission line
loss isnt increased excessively when the line loss is under about 2 DB and
the VSWR is as high as 3:1, and that S-meter readings arent measureably
degraded when the receiver sees these signals thats not coming in with a 50
ohm internal impedance.


Hi Jerry,

It seems your question isn't going to be answered except to three
decimal places.

You are right, no one will notice much difference to mismatches such
as you describe. I know that your interest is in satellite plots of
weather conditions. You may experience some drop out - snow in the
picture. However this would be for marginal signals, and I am sure
that the uncorrelated noise would only slightly degrade the contrast
or detail.

I've played with WEFAX over HF to worse conditions and those pictures
came out quite readable.

73's
Richard Clark, KB7QHC