"Ed" wrote in message
.93.175...
Does anyone here have an MFJ telescoping antenna mast, model MFJ 1910?
I have a 30' no-name mast marketed as a flag mast for RV'ers. At full
extension it bends quite a bit at the top when supporting an 80M inverted
V
/ Dipole of #14 copperweld. My question is, does the MFJ antenna mast
bend a lot under similar circumstances?
I have never seen one of the MFJs, but I was also interested.
When I asked about them at my friendly local HRO, I was told
that they're as flexible as a fishing pole near the end, and that
I probably wouldn't be happy if I actually tried to hold anything
up with one. Although disappointed, I took their word for it,
and passed.
If the MFJ is like the DK9SQ pole, it will be very flexible at the top.
One section down from the top, at about 29ft, the DK9SQ *will* hold up a
G5RV - but only if the whole antenna is ultra-lightweight.
Don't even think about the typical #14 dipole with big, heavy
insulators! The pole won't hold one of those above the 20-25ft level. My
GM5RV/P is made of thin hookup wire with a lightweight center insulator
(a small plastic box that drops over the top section). End insulators
are simply the monofilament fishing line that continues on down to the
tie-offs.
Obviously the pole will bend over at the top, and it's an art to get
everything tied off and tensioned just right. You have to accept that
the whole thing will wave around in even the slightest breeze... but it
will also ride out a full gale.
If you want these poles to stay up, you have to twist each joint into
place as hard as you can, and fix it with PVC tape. If you don't, the
back-and-forth leverage of the wind will loosen the joints, and then the
top part of the pole can slam down into the lower part causing damage.
But having said all that, these flexible lightweight poles can get a
temporary inverted-V into the air in places that would otherwise be
impossible.
Has anyone tried the new 40ft pole from Spiderbeam in Germany? This
looks much better:
http://www.spiderbeam.net then click on "Heavy duty
fibreglass poles".
--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek