Hi Doug,
>Your compromise preserves 80M without retapping the coil, I guess, but
>the result is still an inverted L with only 27' or so of vertical, a
>small improvement over the inverted L using the Hytower MK-160A add-on
>that preserves 80, 40, 20, all the bands.
In my tests with the MK-160A inverted-L kit, I feel the base coil is best.
I can't see the scheme I presented as an inverted-L. It's more like the
design HyGain uses on their 402BA beam. It can be "tuned" from the ground.
~ 52 ft ~ 52 ft
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And my question to the "gurus" is if they think it would be significiantly
better than the base coil to make it worth trying.
>I've never heard of the base insulators arcing over. They're at a low
>voltage point so I don't think that's a problem. However, the insulators
>at the top tower section are at a high voltage point and, Hygain recommends
>running only 100 watts to the Hytower on 160M.
I've had one base insulator arc over. Never a 2" top insulator fail. I've
only had 1100 W output (L-7B) on my hytowers. I don't know if it really
makes a difference, but I'm thinking of sawing a slit on the 2" top insulators
so they will expand/compress. At the point where the U-bolts attach, wrap
teflon pipe thread tape onto the 2" OD tubing. Expand the insulators over the
tape and reinstall the whip to the tower. I'd think that would give some extra
HV insulation at the top. Is this a good idea?
>I live in a very windy area and have never had any problems with the
>mechanical strength of the aluminum tubing section.
The only problem I've had with the "whip" is the 2" to 1.25" reducer.
With the varing wind it stretches and the "whip" slides down into the
2" section. Other than that, mine have survived big winds and ice. I
now have them pinned.
>I think the Hytower is an excellent antenna on 40 and 80, and can be
>pretty good on 160 as a base loaded vertical. You're right, there's no
>easy way to top load the Hytower that I know of.
I think everyone agrees to this fact. Especially if your property only
allows unguyed antennas.
>I have considered adding an 8' section of tower to increase the total
>height to 60'. I think it would perform better on 160M, but am not
>sure I would be able to get it to resonate on other bands?
>73, Doug W2CRS
I have also considered another 8' section. I called Rohn and they don't
manafacture straight sections anymore. The idea of ordering (abt $48) the
next section (BX-4) and cutting it off to fit the insulated base is a
good idea.
Bill K0HA wrote:
>climbing the tower to make the change... For that matter, changing
>from 160 meters to any other band would require climbing the tower...
>Contrary to K5QY's mechanical complaints, I climbed the tower on some
>awfully windy days (during contests) to change bands and never had
>any physical problems with the tower.
Bill we have different safety thresholds...I'll never climb a hytower.
When the weld on the base that's opposite from the hinge side failed,
it could have been because it was originally defective, or it could have
been the way it was positioned. Our winds are generally north or south.
When you fold the hytower it lays to the south. All others lay to the east
or west so possibly the wind forces are shared by all the welds.
There have been other good ideas posted; keep them coming.
73, Dick - K5QY
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