MA5B background noise
The noise stays the same when I turn the beam.
I will try to get a recording done this weekend if I can.
I just pulled out the PL259, so just the canter pin on the PL259 on the
canter fed dipole was connected
and the noise increased with the signal and then dropped when the PL259 was
screwed back in. I had the same on the Cobwebb.
When I did this on the MA5B the 10, 12, 15 and 17 meter bands did the same ,
on 20 meters it was different. When I pulled out the PL259 so just the
canter pin of the PL259 was connected the noise dropped and with the PL259
screwed in
fully the noise went up. The opposite to what I thought would happen after
trying this out on my other antennas.
Andy
"Jim Kelley" wrote in message
...
Andy wrote:
I've swapped the feed line over and its still the same.
When I put the antenna together I made sure all connections where good
and the analyser gave a good match on the frequencies I want to use.
I did use some conductive grease for the first time on the antenna.
Wonder if the grease is the problem or maybe this antenna just picks up a
lot of background hiss.
Andy
The instruction manual for the antenna doesn't make it real obvious how
the feedline attaches, but it looks to me like the antenna doesn't have a
low DC resistance - like a loop would, for example. It's probably
reasonable to expect this type of antenna to be noisier than a loop. I
think Butternut attaches the feedline in a similar fashion on their HF6V,
but puts an air core choke (from memory, 15-20 turns, 14 awg, approx 1"
dia x 2.5" long) across the feedpoint. That may just be for noise because
the antenna seems to have the same performance with, or without it.
Perhaps you could try the same with the MA5V.
I think what the OP was getting at is the noise should be a lot louder
with just the center conductor attached to the radio, and then get quieter
when you thread the barrel on. If it doesn't do that, then there may be a
connectivity problem somewhere.
ac6xg
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