I have the 7-3 at my station in Barbados. It definitely works well and time
will tell on its reliability. Judging from the amount of spare parts left
behind from the previous owners, the antenna has required a fair amount of
maintenance. Barbados has a brutal salt breeze that will turn a black
tailtwister white in a couple of months.
My first hand experience started two summers ago. I took the antenna down
as it had broken under the prior owners and they did not get a chance to fix
it. As near as I can tell, there is a fatal mechanical design flaw where
the linear loading wires touch the element tip. There is a fair amount of
flex at this point and the aluminum wire will fatigue and break. When I
took the elements down, this joint was broken on both ends of the reflector
and one of the two ends of the driven element. The other driven element end
had wiggled the bolt loose so the stress on the joint was relieved. (For
some reason the director was fine) I had brought down a spare set of loading
wires but it was clear that the same thing would happen again. Under time
and material availability limitations, we decided to connect a stranded wire
in parallel with the last 6-8 inches of the loading wire. Should the loading
wire break again, we would have a back-up. This is a bit of kluge but has
worked for two years in a very tough environment. Unfortunately, I cannot
tell if the aluminum wire has already broken or if I still have redundancy.
I think the failure mode I saw is not uncommon as there was an article in a
recent CQ Magazine addressing this problem. Their solution was to use a
continuous run of copper wire to avoid all of the joints and a piece of
flexible braid at the end to absorb the vibration.
What I do like about the antenna is that the assembly is very repeatable and
should give predictable results (unlike the Force12) and does not have
fragile capacitance hats out on the elements that can be easily hung up and
bent during installation (like the Cush Craft).
Bottom line - although not scientific - for a 2 element 40, the Cushcraft
seems to have the most ardent supporters.
73, Tom W2SC
-----Original Message-----
From: Mel Martin [mailto:ve2dc@rac.ca]
Sent: Thursday, April 03, 2003 9:56 AM
To: lclarks@nc.rr.com
Cc: towertalk@contesting.com
Subject: [TowerTalk] Hy-gain 40M
I'm a big Hy-gain fan... present antennas are a 105/155/205 and a DB1217 and
until recently a TH7 (great antenna!)...
The only Hygain antenna i don't like is the 40m...
I had it up as a 3 el at 150ft... performance was first rate... but
unreliable as hell... had it up and down the tower countless times for
repairs... finally changed it to 2 el... not much difference in
performance... but lost that in the ice-storm of '98. I wouldn't put up
another! Next one will be the Optibeam... much better bandwidth...
Others seem to have had more success...
Good Luck & 73...
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
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