Your Pointy Rohn 25 and a shelf

[BK1ZX70SFL at aol.com]

If you have tower with a "pointy" top section you have probably been told by
now that you messed up. That was one of the first lessons I learned from
following the contest reflector....thanks K5ZD, I think. 

Trade your pointy top section with a guy for a straight section...yes you
will take a bit of a loss but not a bath....so trade it for a straight
section and some PL259s.... And later you will thank yourself. Why? 

Because, flat top sections are better. Why? Becuase you can stand on them
when you are working on that upper stacked yagi or the truss for your beam.
You can't find a place to step anywhere near the top of a pointy section.
 Yes it sounds hairy - standing on top of your tower! Hairy, but it is o k
work. With your mast well secured in your rotor you have an excellent place
to belt to - wrap your lanyard several times around the mast, and voila you
are secured and unlike the usual rungs you actually have something flat to
stand on! Your feet prefer it at the top...mine do!

The second shelf for a thrust bearing is a must for ease in rotor/rotator
instalation and maintenance work. By having the shelf above the rotor you
have a point where the downward weight of the mast and antennas can be born
when it is time for you to take out the rotor for service.

Imagine taking the rotor out, it is probably going to come sideways out of
the tower,  right? What do you do with all the downward force from the weight
of the mast and antennas while you are trying to slide that rotor out? Easy -
just put a clamp around the mast above a shelf that is half way between the
rotor shelf and the top of the tower. HyGain's cast two piece boom to mast
clamp with the two toothed jaws (saw that three times fast) is perfect for
this....think it is what they use on 204BAs. If the clamp is applied to the
mast just above the new shelf above the rotor it now takes the weight of the
antennas when you need to remove the rotor. If you take a pry bar up the
tower (don't drop it!) you can goose the mast/ants up a liltlle before you
tighten that toothed clamp up above. When the rotor is back in place up top
on the rotor shelf you loosen the toothed clamp and the mast will slide back
down to the rotor....note: (K7LXC probably will back me up on this) most
rotor manufacturers encourage the weight of the antennas to be carried on the
rotor as opposed to the mast being supported vertically by a thrust bearing.
This is because if you have other than a perfectly true running mast there
will be up and down movement of the mast as it rotates....and if you force
that movement upon the rotor its housing will be pulled up and down as the
mast turns.  If the mast was free it would simply ride up and down  as things
turned with no upwards force applied to the rotor. Use thrust bearings for
sideways thrust control, any major rotor is well able to handle the downward
force of the antenna's weight...that part is easy.

Okay so the mast is passing through the flat top of the tower and then the
other shelf...and it is supported by the clamp while you are working on the
rotor, what have you forgotten? 

To keep the mast from spinning around, I take a short length of pipe with a
boom to mast clamp on one end of it and attrach it to the mast someplace
within the tower. You can then lash this pipe to a tower leg and the antenna
will not windmill on you. 

You can leave the beam lashed in pointed at Europe (Left Coasters may decide
to pick JA...and you Euro guys may pick NYC) while the rotor is being worked
on...since you have it so well supported and fixed you can even mail that
rotor back to (fill in your favorite rotor fixing service here) and
everything will be just fine until it comes back.....that is unless the last
country you need for the DXCC Honor Roll comes on the air and it is So
Shetlands and you are stuck trying to work them off the side of your f/b
optimized yagis!!!!!

Oh well....always have a backup antenna, right...and if your antenna farm has
several of the same rotors, why not invest in another one so it can be put in
while the broken one gets re-built. Some of the re-build services sell
re-built ones ya know!

Jim  K1ZX

>From David Robbins <ky1h at berkshire.net>  Sat Apr 13 20:06:14 1996
From: David Robbins <ky1h at berkshire.net> (David Robbins)
Date: Sat, 13 Apr 1996 12:06:14 -0700
Subject: Pointy tops on Rohn 25
References: <199604122127.RAA12444 at yoda.fyi.net>
Message-ID: <316FFB26.7E36 at berkshire.net>

robrk at fyi.net wrote:
> 
> Rohn makes one for the pointy top......Might use smaller mast than you
> want....The rotor
> shelf might be the better idea...If you ever go for more tower, get the flat
> top
> and be able to use the same bearing............
> 

i have both flat and pointy tops here... i much prefer the pointy ones.
if you use the flat top and put the bearing on the top plate with the 
rotor on a shelf below it what happens if you have to take out the 
rotor???  you have the mast in the thrust bearing with no sideways 
support.... i get very worried about destroying the bearing with the 
mast tilting so spend lots of rope and time tying the bottom of the mast 
and the antennas to keep them level.  an alternative is to put a second 
thrust bearing on another shelf down lower to hold the bottom of the 
mast, but then you're back where you end up with a pointy top anyway.

the pointy tops (guide tubes) do just that, they guide the mast and hold 
it vertical against the side forces from the antennas.  that leaves the 
thrust bearing on a plate below the guide tube to do what it is designed 
to do, hold the mast and antenna weight (vertical thrust) instead of the 
side forces.

73, dave
-- 
ky1h at berkshire.net   or   robbins at berkshire.net
http://www.berkshire.net/~robbins/ky1h.html


>From Jan Almedal <janalme at sn.no>  Sat Apr 13 13:59:10 1996
From: Jan Almedal <janalme at sn.no> (Jan Almedal)
Date: Sat, 13 Apr 1996 14:59:10 +0200
Subject: in favour of Trey's opinion!
Message-ID: <199604131301.PAA01668 at ekeberg.sn.no>

At 17:47 12.04.96 -0700, you wrote:
>
>Since this message is not contest related, I think a better
>place to make this type of annoucement would be in a general
>purpose amateur radio group, like rec.radio.amateur.misc.
>
>It's clear the CQ-Contest mailing list has lost a bit of its
>focus lately.  I would like to request that everyone take a 
>little time before posting messages to CQ-Contest and consider
>whether the thread is really germaine to contesting.
>
>--Trey, WN4KKN/6
>
>

Hello Trey.

This mail just to say I like your postings! I have been devoted to contests
since I got licensed in -76. I have been on the Net for a year, and
subscribed to this reflector since I discovered it. Due to this reflector I
have learned tremendous on how the 'big guns' operate, and also got lots of
impulses on how to improve my own contesting. I hope this will continue!

My contribution to the contest world is mostly my web page, containing a
collection on contest rules. Contesting is not too common in Norway (am I
the only LA on the reflector?), but increasing.

I hope your postings will clearify that this is a CONTEST reflector, and all
subjects should relate to contesting. There are lots of other media (first
of all USENET) for other topics!

Lets stay to contesting, discussing station set-ups, operating ethics,
antennas, propagations, etc!

Lately I have especially enjoyed the discussion about use of power (My view:
we should all stay to our license limitation (1kw in LA)), and also about
contest categories (why not use ERP power (like VHF) instead of output power).

Finally, hope this remains a CONTEST reflector!

Thanks for your good work Trey!

73 de
Jan / LA9HW

- - -
NRRL HF Contest Manager
Complete HF Contest Calendar: http://www.sn.no/~janalme/hammain.html


>From Charles H. Harpole" <harpole at pegasus.cc.ucf.edu  Sat Apr 13 15:03:39 1996
From: Charles H. Harpole" <harpole at pegasus.cc.ucf.edu (Charles H. Harpole)
Date: Sat, 13 Apr 1996 10:03:39 -0400 (EDT)
Subject: Contest Stations in Emergencies
Message-ID: <Pine.SOL.3.91.960413100056.6222G-100000 at Pegasus>

Thanks for the good words, Steve re EL traffic.  Of course, the tv did 
not get the part about my station "being the only one to contact EL" but 
otherwise, ham radio looked very good on the Orlando channel 6 that 
nite.  This specific emergency is especially wrenching because all one 
can do on the US side is still not what some needed--evacuation under 
armed protection.  It is a very dangerous and sad situation there, it 
appears.  de K4VUD

>From n1mm at usa.pipeline.com (Tom Wagner)  Sat Apr 13 15:07:07 1996
From: n1mm at usa.pipeline.com (Tom Wagner) (Tom Wagner)
Date: Sat, 13 Apr 1996 14:07:07 GMT
Subject: Kenwood s-meter lamps
Message-ID: <199604131407.OAA28014 at pipe3.t1.usa.pipeline.com>

On Apr 13, 1996 04:14:05, 'AA7BG--Matt <AA7BG at worldnet.att.net>' wrote: 
 
 
> 
>Thanks to whoever suggested this and thanks again to Danny. My ON/OFF
switch 
>has been working fine ever since he said to "bounce" my finger of it
quickly 
>at a steep angle. 
 
Matt -- 
 
Why don't you just leave your radio on, and use a power strip to switch it
on? 
 
I use "power console" sold at computer shows.  You probably 
have seen them.  A master switch and five individual switches.  I use it to
 
control the computer, radio, 12v equipment, shack light and printer.  The
radio  
and 12v circuits have power strips attached to them so that one console
switch 
can turn on multiple pieces of equipment.  Power consoles usually also
contain  
MOV's for some level of surge protection.  They cost about $15-20 at the
shows. 
They are made with big, flat metal cases.  Great if you want to add any 
power line filtering or additional MOV protection (like Polyphaser). 
 
While you are at it, get cable that will allow your color monitor to be
switched by 
the IEC plug on the back of your computer.  When the computer is turned on,

the monitor is turned on! 
 
Everyone at my house loves this setup, except my wife.  She wants to  
know why the computer and radio come on when she turns the light on!