[BC] Re: Copper program Loops

[Wooten, Charles]

Re Mike's (really NIU's) remarks about warranty, recourse on bad used
equipment.....I have NEVER seen an 111C go bad....they will even pass
composite....many years ago I used one to get rid of a really bad ground
loop between an Optimod 8000 and a Collins 310Z exciter with the "STL"
card in it.

Charlie Wooten
Clear Channel Radio
Panama City, FL 

-----Original Message-----
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Sent: Friday, April 06, 2007 1:04 PM
To: broadcast at radiolists.net
Subject: [BC] Re: Copper program Loops


In a message dated 4/6/07 11:39:29 AM Central Daylight Time,
broadcast-request at radiolists.net writes:

<< From: Mike McCarthy
 Subject: Re: [BC] Copper program loops
 To: "Broadcasters' Mailing List" 
 Message-ID: <5.0.0.25.2.20070406090718.02d0fc08 at pop.ais.net>
 Content-Type: text/plain; charset="us-ascii"; format=flowed
 
 Jeff,
 How long is the circuit?  If its less than 5000 ft. of wire feet, then
a  pair of 111C's back to back in 150 ohm configuration should work
fine.  Otherwise, the associated equalizers will be needed.  Both can be
had surplus.  E-bay regularly has them for $50 ea.
 
 I have in the past used a graphic equalizer to smooth out the curve if
it  was possible.  But depending on the amount of correction needed,
that would  be a worse off selection.
 
 Also, you could also run a DC closure on the pair by inserting a good
sized  cap between the coils at the center and injecting 12-48VDC on the
pair.
 
 I have an equalizer and 111C if you want to try that route out before
committing.
 
 MM
  >>

Mike:

The split coil and big honking capacitor is "out" for the contact
closures. 
That works fine for Two Way but that big cap and the inductance of the
split repeat coil winding produces a nice notch filter at some audio
frequency. Hum can also be an issue. No thank you. We will use a
separate loop for signaling.

It is a little over 5000 feet of wire. NIU does not have a purchasing
protocol for buying things on Ebay. yes, the 111C is a great solution,
even tho ugh it goes back to the days when dirt was new. NIU frowns on
buying used things because there is no warranty recourse, among many
other objections. 

I was really hoping for, and prefer, an inexpensive 21st century
solution for this project. I don't want any unlicensed radio solutions.
I would prefer an economy T1 encoder-decoder for copper or fiber. There
is another dish on campus that I can have, and there's fiber from there
to here. 

I cannot afford 25 grand for a high end T1 for a backup. It would
therefore appear from your posts and those of others, that the 111C or
Jensen transformers are the best choices. Anyone disagree? At my age,
I'm a bit parano id about resorting to "old fart engineering" by using
things that were popular 20 years ago. But if that's the best approach,
then why not? I just want to be sure that it is :-)

Thanks,

Jeff Glass, BSEE CSRE
Chief Engineer
WNIU WNIJ
Northern Illinois University

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