A local station recently purchased a couple of the M2 3 element 40
meter antennas. We were impressed with the antennas while we were
putting them together...things fit well, nicely machined parts, etc.
However, they've been up now for about four weeks and problems have
developed. The SWR on the antennas is all over the place. While the
SWR varies somewhat in windy conditions (to be expected), the antennas
show widely varying SWR from day to day. The antennas' SWR are
normally about 1.6 at the bottom of the band. As you go up in
frequency, they go to 1:1, then rise. (again, as you would expect).
However, on some days they're flat across most of the band...other days
they start out at 3:1 at the bottom of the band, drop to about 2:1 at
7040, then going up from there. We've also seen the SWR take quick
"jumps" which would seem to imply problems with electrical/mechanical
connections.
We have pulled down the antennas and examined them closely (several
times). We found that the set screws which hold the linear loading
rods had worked lose. After talking with M2, we've tried various
arrangments on the set screws including double set screws (one to lock
the other in place), stainless steel machine screws with locking nuts,
etc. None of these solutions have held up more than a few days.
A good connection with the linear loading rods is obviously crucial to
the operation of the antenna. Anyone out there have similar problems
with the large M2 antennas which use linear loading?? Any solutions??
We haven't really gotten any good solutions yet from M2.
73,
Dave
WA0FLS
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