Here, pass that steering wheel into the backseat where I'm sitting... I might
as well give this a shot too... :-)
I have been very interested in reading this thread and the good suggestions of
cause, effect, remedy. I think the suggestion from Bill - W2WO is a practical
test to divide and conquer the problem. This procedure requires the customer to
do some Field Engineering,. In my opinion, a "service junction box" should be
installed at the base of the tower in any case.
On the other hand, I would expect the Factory to investigate this issue. For
example, they could throw a 1,000 feet of cable between a controller and 4
EHU's and get their scope out. Then take a look at the pulse train at the Power
Supply/Controller end and compare it at each EHU. This puts the engineering
back where it belongs, at the Factory. (I suspect pulse deterioration from one
end of the cable to the other, as has been suggested.)
The next Factory step would be to cut the cable in half and compare the
results again. An approximation of cable length effect could then be determined
with the expectation of determining a "maximum cable length" specification.
Ultimately, this testing could identify what controller cable type would be
acceptable with very long runs (if the cable IS the issue).
Using the "shotgun" replacement approach is certainly acceptable in normal
cases. (It was faster and more economical to replace computer boards than
troubleshoot to the component level in the field.) This approach gets the
client up and running promptly. But in this particular situation, a 500 foot
controller line doesn't seem to fall into the "normal" installation to me.
So that's 4¢ from me (inflation), and I'm anxiously waiting to hear about the
73 de Bob - KØRC in MN
(Retired Field Service Engineer - Linotype/Hell Company)
Date: Mon, 11 Jun 2007 10:51:10 -0400
From: Bill Ogden <email@example.com>
Subject: [TowerTalk] SteppIR problem
Content-Type: text/plain; charset=US-ASCII
Simple suggestion: Ask the SteppIR people for a control-box connector with
a few feet of cable on it. (That is, do not try to solder one yourself. It
is difficult to do accurately without a proper jig.) Take this to the base
of the tower. Cut the existing cable and connect all the pigtale lines at
this point. A little messy with the 16+ wires, but it should be safe and
accurate. Operating the control box from this point should resolve all the
questions about the 500' cable. Of course, this assumes you can get 110v
power to the tower base. Consider borrowing a generator, if necessary.
Bill - W2WO
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