[BC] Re: Copper program Loops

[Mike McCarthy]

Next Media is using a long lines AES encoder for their station here. The box is designed to drive a LONG cable pair and they're driving 600 ft of cable to their TX. I don't know if it will make 5000FT. on 22/24Ga. wire however.

I recall it was less than $1K.  It works pretty good and has survived a number of BIG lightning events.

MM 


> 
> 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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