[BC] Re: Copper program Loops

[Xmitters@aol.com]

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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