Crankups and Rotating 55
W7NI at delphi.com
W7NI at delphi.com
Wed Aug 16 15:44:27 EDT 1995
First, I would like to say that the worst crankup horror story I ever heard
was told to me by KL7RA. It was a true, personal experience of his and
I would like to encourage him to share it with all of us on this reflector.
It is his experience and his story and I think there are several very
valuable lessons for all of us in it. He has to tell it and not me since
that is the best way to get it accurate and it is possible he doesn't
even want to talk about it again so unless Rich is convinced to tell it,
it ends right here.
Second, K0SF has asked about insulated Rohn 55 and KM9P said he
had some big insulators. I do too and I am willing to sell a few of them.
My insulators were part of a Bonneville Power substation and were used
to support heavy stuff. I weighed the heaviest one and it is 120 pounds
with smaller ones weighing in as low as 50 pounds with several sizes in
between. They are all about 16 inches high and vary in diameter up to
18 inches for the big ones.
Here is a description of the largest ones. The bottom is a flat faced
cast steel flange with a 10 inch diameter hole pattern for 8 bolts that
are 5/8 inch in diameter. With care, this could be mounted to a
buried concrete block to serve as a tower base with 8 threaded studs
protruding from the concrete. I have similar insulators with different
hole patterns. The top is also flat faced and has a 4-bolt threaded
hole pattern arranged in a square that is about 4.25 inches on a side.
The top threaded holes appear to be for 3/4 inch bolts. You could
interface a tower to this flat face without welding to it. These instualtors
look strong enough to support many tons of weight.
What I wonder about is whether they are any good at all for rotator
torque. I envision a big bearing and the insulator at the base of the
tower. The roator would be ground mounted and a chain drive would
connect the rotator to the tower. If the chain drive is attached below
the insulator, the insulator has to take all of the torque. If the chain
drive is attached above the insulator, you have to somehow insulate
the rotator or you reground the tower through the rotator eliminating
the effect of an insulated tower. Someone may have already worked
out a good scheme to take care of this, but I have not seen it.
The insulators were manufactured by NGK of Japan and have
several identifying numbers on them. Maybe they are specified for
torque. If you are interested, I could take a couple of Polaroid
pictures and provide you with the idenifying numbers so you can
do some research.
It is a little tricky to ship these safely since they are breakable and
damn heavy but the guy across the street is handy with wood and
can build a custom box out of two by fours and plywood that I
am sure could get them to you in one piece.
I would be happy with $50 for one of these beasts plus freight
plus a few bucks for wood packing materials and labor for my
neighbor to build a box.
By the way, I have sold a bunch of these already to guys who plan
to build four sqares for 80 or 160. No torque problems with those.
Stan "W7NI at delphi.com"
>From n4zr at ix.netcom.com (Pete Smith N4ZR) Wed Aug 16 19:48:04 1995
From: n4zr at ix.netcom.com (Pete Smith N4ZR) (Pete Smith N4ZR)
Date: Wed, 16 Aug 1995 11:48:04 -0700
Subject: HF Launch Angles
Message-ID: <199508161848.LAA09840 at ix3.ix.netcom.com>
>If you want to learn about how antennas work at various heights over
>real terrain, or you are ready to purchase your ultimate contest QTH
>and want to know how to plan antenna heights, you should pick up the
>July issue of QEX magazine.
>
>The lead article is 13 pages of super discussion concerning launch
>angles. It is written by contest super op Dean, N6BV.
>
>At the price of $1.75, the information in this issue is a steal!
>
>Thanks to Dean for publishing his valuable work!
>
>73,
>Tim K3LR
>
>k3lr at telerama.lm.com
>
>
I second the motion. The software Dean uses for measuring the effects of
terrain is also available, either from the ARRL BBS or from various sites
that FTP materials from QEX - buffalo.edu is one. It's called YTAD.ZIP.Try
it -- it'll really whet your appetite. Thanks, Dean!
73, Pete Smith N4ZR
n4zr at ix.netcom.com *** please note new address ***
Radio Free West Virginia (under construction)
>From Assarabowski, Richard" <AssaraR at utrc.utc.com Wed Aug 16 20:35:00 1995
From: Assarabowski, Richard" <AssaraR at utrc.utc.com (Assarabowski, Richard)
Date: Wed, 16 Aug 1995 15:35:00 -0400 (EDT)
Subject: Final Notes on IC-765 Mods
Message-ID: <30324880 at msgate.res.utc.com>
To W5KI/2: What is your e-mail address for the summary of IC-765 mods???
-- Rich K1CC
assarar at utrc.utc.com
>From barry at w2up.wells.com (barry) Wed Aug 16 18:28:29 1995
From: barry at w2up.wells.com (barry) (barry)
Date: Wed, 16 Aug 95 13:28:29 EDT
Subject: HF Launch Angles
Message-ID: <72sX0c2w165w at w2up.wells.com>
k3lr <k3lr at telerama.lm.com> writes:
> If you want to learn about how antennas work at various heights over
> real terrain, or you are ready to purchase your ultimate contest QTH
> and want to know how to plan antenna heights, you should pick up the
> July issue of QEX magazine.
>
Sounds like an article that belongs in NCJ. Too bad it didn't wind up
there. Does ARRL (or anyone else) sell individual copies of QEX?
--
Barry N. Kutner, W2UP Internet: barry at w2up.wells.com
Newtown, PA Packet Radio: W2UP @ WB3JOE.#EPA.PA.USA.NA
Packet Cluster: W2UP >WB2R (FRC)
.......................................................................
>From barry at w2up.wells.com (barry) Wed Aug 16 18:31:12 1995
From: barry at w2up.wells.com (barry) (barry)
Date: Wed, 16 Aug 95 13:31:12 EDT
Subject: Grounding
Message-ID: <P7sX0c3w165w at w2up.wells.com>
Hi all - I am planning on installing a concrete swimming pool in my yard
in the near future, and wonder if there would be any use (or danger!) of
grounding the tower to the pool ground.
My understanding of the construction details is they bond the rebar
together and run a ground wire to the pool equipment. The pool will be
about 50-60 ft from the tower base.
Looking for comments from our Contest experts...
73 Barry
--
Barry N. Kutner, W2UP Internet: barry at w2up.wells.com
Newtown, PA Packet Radio: W2UP @ WB3JOE.#EPA.PA.USA.NA
Packet Cluster: W2UP >WB2R (FRC)
.......................................................................
>From Roger A. Cox WB0DGF" <75052.3037 at compuserve.com Wed Aug 16 21:49:36 1995
From: Roger A. Cox WB0DGF" <75052.3037 at compuserve.com (Roger A. Cox WB0DGF)
Date: 16 Aug 95 16:49:36 EDT
Subject: Log-Periodic Dipole Arrays
Message-ID: <950816204935_75052.3037_GHJ166-1 at CompuServe.COM>
Will,
What I mean by real performance is the "Actual" gain vs. the "Advertised" gain.
Almost ALL of the commercial antenna manufacturers have inflated their dBd gain
by as much as 2 to 4 dB! For example, a 13-30 LPDA on an 18 foot boom has a
MAXIMUM gain of 4 dBd (6.15 dBi), while several companies are advertising either
6.4 dBd (Brand C) or even 7.9 dBd (Brand M) for this size LP. Check out the
ARRL graph on page 10-3 that I mentioned, and the references it cites. This
size LP has TAU=.85 and SIGMA=0.05. This is the theoretical maximum, which will
be reduced even more by resistive losses.
73, Roger WB0DGF
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