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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