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[TowerTalk] ICE model 348 rotor cable protector

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Subject: [TowerTalk] ICE model 348 rotor cable protector
From: (
Date: Mon, 14 Jul 1997 13:57:08 -0500
A bit of confusion has existed about the application of the ICE model
rotor cable transient voltage suppressor and RF bypass unit.

1. Each model 348 will support up to 8 rotator conductors.  The device
will provide a MOV to ground and a RF bypass capacitor to ground for
each of the eight lines, independently.

If 12 conductors are used, 2 units will be needed: (8+ 4 =12)
with 4 each line protectors to spare.  If only 5 conductors are used,
then a single unit is needed with 3 each spares.

2. Where is the model 348 best placed ?

For each of the 8 control lines use one unit at the tower base AND one
unit at the station single point ground penetration panel. ( ie where
the control cables enter the building.)
If the budget only permits a single unit, place it at the tower base and
bond the unit to the gound system.

3.  How do I insert the unit into the rotator control line ?

remove the outer insulator for at least 6", exposing all of the
individual conductors.
remove enough of the insulation from each conductor to allow putting the
bare conductor under each of the eight screws on the unit.  Keep in mind
that the outer screws on the terminal strip are grounded and secure the
terminal strip to the chassis. Therefore the 4 inner screw terminals of
both terminal strips are for the rotator cables.....
If the rotator control cable is shielded, bond the shield to the
grounded terminal screws on the unit.

An alternative is to cut each conductor, strip off enough to go under
the terminal screw
and put BOTH of the cut, bared, conductors under a single screw
One color conductor to a screw terminal.

Crimp on terminals are another alternative......

4.  Where can I get the ICE devices ?

Call Industrial Communications Engineers LTD at 1-800-423-2666 and ask
for STOCKING distributors of their products.

I usually buy my ICE stuff at RADIOWARE, in MA at 1-800-950-9273, ask
for John...
I preferr RADIOWARE because they stock most of the ICE things I need.
The RADIOWARE catalog has a lot of the ICE products with specs.

5. What are the periodic maintenance requirements for the model 348
suppressor unit ?

MOV's can fail fully shorted OR fully open, The fully open condition is
easy to visually inspect. They are simply blown apart.  If the MOV is
intact and looks OK it must be electrically tested to ensure it will
conduct at about 66 VDC. Hook up a variable DC power supply, 0-100VDC,
apply it to the suppressor terminal under test and chassis ground.
Starting at 0 volts DC , monitor the conducted current. Conducted
current should be minimal until about 80-90 VDC when the working MOV
kicks in...
If you cannot find the "conduction knee" check your test set up,  then
try a known good unit... Replace all defective MOV's.

Typical impedance to ground for the unit in front of me is very high,
well into the megohm range. As measured with a FLUKE 87 DVM.

For areas with much lightning, I would check each suppressor at least
annually (once every year) with a good visual AND electrical performance
test on the bench.
For other areas, inspect and test every 2 years. Spare units come in
handy, rotate your stock.

What PM do the commercial folks do ?   Usually none, crisis maintenance
is more easily justified to the beancounters.

 I hope this helps your understanding on how to use these lightning

 Stan, WA1ECF   Cape Cod, MA   FN41sr

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