The results of the 30th Telephone Pioneer QSO Party will be in the mail
on Tuesday, Sept. 5. Anyone wanting the stuff on e-mail, give me a
buzz.
We had about 321 entries from all over NA - every year when Jim, W6KXG
and I do the compilation, we learn to appreciate the efforts of others
who spend their precious free time on contest results.
The 31st edition of TP QSO party will be at the same time as the ARRL
160 contest. If you do both 160 and TP, you don't sleep much.
Fun way to keep in touch with old colleagues and acquaintences from the
telecommunications industry.
BTW, one can become a telephone pioneer and join in on this event if
1 You are employed by a telephone company
All the divested Bell companies and various independant
companies, together with AT&T itself, sponsor Pioneering
which, is a service organization.
2 You must have a certain amount of time in on the job.
I think its just 6 months these days - Used to be years
and years.
oh yeah, Dec. 2 and 3 are this year's dates. CU there.
Contact me on e-mail edwoods@pacbell.com
(916) 972-2254 w
(916) 489-5720 fax
73
eric, not N4BO
edwoods@pacbell.com
>From David & Barbara Leeson <0005543629@mcimail.com> Sat Sep 2 21:58:00 1995
From: David & Barbara Leeson <0005543629@mcimail.com> (David & Barbara Leeson)
Subject: Ring Rotator Coax
Message-ID: <33950902205833/0005543629NA1EM@MCIMAIL.COM>
Coax Routing with Ring Rotators
There is no information that I have found that tells how to route coaxial
cable around a ring rotator so it won't get caught and chewed up in the
gears. Here's a method I use, based on discussions with K3LR and W0UN.
Because the ring rotator is below the antenna, you need to run the coax up
the tower (I like it inside) to a point well above the boom height. I have
found it's better to use a short jumper cable with UHF connectors on each
end, so when it gets destroyed I can replace it without soldering connectors
on the tower. I have one cable along the boom of the antenna, mounted when
the antenna is on the ground and another in the tower. The jumper goes
between these two, and is tie-wrapped and taped to the tower at one end and
to the boom of the antenna at the other end.
To visualize the geometry, picture the extreme case where the antenna is in
the middle of its rotation (typically north) and the cable attachment point
is on the boom opposite a tower leg, as shown in this rough sketch:
x x
x\ x
x \ x
x \ x
x \ x
x \ x /\
x \x / \
x x / \ | |
x x\ / x \ | |
x x \ / x | \| |
x x \ x | | |
x x \ x | | |
x x O x | |
xxxxxxx xxxxxxx | |
x x
When antenna is rotated in either direction to the limit (typically south)
it is now on the same side as the tower leg and the coax develops slack that
must be taken up in a loop of some sort, as shown here:
x x
/x x
/ x x
/ x x
/ x x
/ x x
| x x
| x x | |
| x x | | /| x
| x x | |/ | x |
| x x | | x |
| x x | | x |
O x x | | x
xxxxxxx xxxxxxx | |
x x
You can take up the slack in the coax with the long trailer hose spring used
to hold the brake hoses up on an 18-wheel truck and trailer, available
cheaply at truck parts stores. Two available springs are
Dorman 070-107 (26 1/2", extends to 8') and
Dorman 070-117 (13 1/2", extends to 3-1/2').
The spring can go to the boom, to the boom guy supports or up the tower leg,
as you choose. If the slack loop is small enough to be sure it won't get
into the gears, I prefer to pull to the boom from the middle of the coax
jumper (I don't let the spring wind around the tower). I attach the spring
with several tie-wraps looped three times around the coax so they won't slip,
then also use some tape. The spring force is not very great, so it won't
chew up the coax.
For boom distance from tower center at midway of rotation (typically north),
the table here shows the calculated minimum length of the jumper cable and
the length difference from mid-rotation to either limit, for 18" tower face
width and 15" radius from tower center to antenna boom:
Height above boom 18" 24 30 36 42
Length of coax 36 39 43 48 52
Length difference 18 15 13 11 10
You can see that the higher you go above the boom, the less slack there is
at each rotation limit. I would use at least a 48" jumper 36" above the boom
(leave a little extra slack, of course), but you can experiment with a scrap
piece of coax or a rope to see how this works for you. The only trick is to
make the attachment point at mid-rotation exactly opposite the edge of the
tower leg you hook the coax to, so it has the same length at both rotation
limits. If you are not using some form of limit switch, leave quite a bit
more slack or be ready to replace the jumper often. Attach the jumper coax
to the tower and boom so that if it does get pulled tight it doesn't pull out
the connectors on the permanent cables.
I'm working up similar information on a closely related problem, routing
coax to clear the bearing on a rotating tower.
I hope this is useful to contesters who are installing ring rotators this
season.
73 de Dave, W6QHS
>From James White <0006492564@mcimail.com> Sat Sep 2 23:06:00 1995
From: James White <0006492564@mcimail.com> (James White)
Subject: Spring loaded coax
Message-ID: <82950902220628/0006492564PK4EM@MCIMAIL.COM>
...several months back Dave, W6QHS mentioned the use of a tractor trailer's
brake line spring to take up the slack in coax when you run it upwards away
from a beam as is necessary with a ring rotor.
....like many contesters, I worship the ground that Dave (and Barbara) walk
upon and I took his suggestion. I was mid-installation of the Hemi 426
4-Element 15 meter beam (on a TIC rotor).
.....I went down to the local truck stop, had some fried food with my good
ole boy buddies and then proceeded next door to the truck parts place. The
spring I purchased was approx 2 foot in length, and seems to be just what
the antenna Doctor ('QHS) ordered. It was $4.95. I don't know if different
grades of these springs exist out there...the truck stop had three choices,
short medium and long....being a registered independant I of course went
with the medium.
......with the beam pointed North (the center of its rotation) the coax
splice was passed through the loop at the end of the spring (which was quite
conveniently just a lil bigger than the PL259) and then it was taped to the
coax at the middle of the slack that existed between where the coax was
taped to the boom and where it enterred the tower. Again, not being one to
commit, I put a caribeener at the far end of the spring and snapped the
caribeener around a tower diagonal brace just far enough away that a lil
tension was present at "North", and the spring would only get tensioned (and
stretched) when it rotated away from North.
.......It seems to be an excellent way to handle this problem, my only
reservation is that it was plated steel and Florida's wonderful heat and
humidity will eat it alive....we'll see how long before it fails - hopefully
I will see it has failed (or is about to) before the beam's coax becomes
lunch for the teeth of the ringrotor.
.........Thanks for another useful tip, Dave...and thanks for having a place
for me to find it, The Contest Reflector, Trey.
73, Jim zx k1zx@mcimail.com
>From barry@w2up.wells.com (Barry Kutner) Sat Sep 2 23:45:14 1995
From: barry@w2up.wells.com (Barry Kutner) (Barry Kutner)
Subject: Ring Rotator Coax
Message-ID: <40LTaD1w165w@w2up.wells.com>
I think Dave may be making it more complex than necessary. In my case, I
have the ring-rotor on the lower of 2 TH7s. The coax comes down from the
upper/lower/both box up above, inside the tower. I bring the coax out
about 2 ft below the ring, leaving about a 5 ft loop, at its loosest
point. The coax attaches to the balun and is held in place on the boom
about six inches away with a few cable ties. The loop swings freely,
below the ring, as it rotates. There's nothing for it to get caught on.
--
Barry N. Kutner, W2UP Internet: barry@w2up.wells.com
Newtown, PA Packet Radio: W2UP @ WB3JOE.#EPA.PA.USA.NA
Packet Cluster: W2UP >WB2R (FRC)
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