Non licensed school station

[busyradioguy]

how much does the phone company charge for that 15 khz line and what type of transformer are you using at each end ? thanks

In the suggested application of "in house telephone", a.k.a. PBX, $0.00. The district uses it's own in-house lines, not the teleco.

 

[dtube1]

Speaking to the issue of dry-pairs - the IT folks at the college I work for have all but abandoned a very clean copper plant. The only apps remaining on it are MAC machines and some security phones and related apps. So, I have probably 45 Jensen JT-112 transformers around the joint to haul audio from almost every building on campus. Just for grins, I ran SMAART (live sound, FFT-based, audio analysis program) on my longest run, which is approx 2800' and crosses (5) punchblocks: the audio was essentially flat from 50hz past 20khz and overall level loss was about 4dBv. I then looped the circuit back (5600') and measured again: the results were a roll-off starting around 16khz and down 5dB at 20khz with an overall attenuation of 9dBv. That line was driven by an ATI DA out. Needless to say, I am a big fan of dry-pairs when dealing with a distributed facility. The xfmrs are about $45/each - I build the terminations on either a rack panel or in a project box.
-D

 

[NSPUNX]

Youre right I should have specified a dry pair but I guess I figured when I mentioned an in house phone system that would clue that in. I would just find an empty line that runs from the building with the transmitter into the telephone room and then find an empty line that runs from the building with the studio into that room. You can just tie them together and place a transformer at each end.

 

[RadioMan203]

You should be fine with that solution. I'm lucky as on my campus most every section of the building has a 100 pair line running from the main data closet (about 60 feet away from the studios) to different data closets all over the campus. One run ends up in the center of the second floor where I'm installing the leaky coax FM transmitter and near the roof access for the Part 15 AM box.

Since some of the control gear will be located behind secured doors I'm remote controlling the two transmitters with a donated Moseley MRC-! remote control - all I have to do is check it to make certain it's still in operating order as it was sitting in storage for some time.

 

[NSPUNX]

Thats the same scheme we use at my college non-comm. The transmitter is located in a locked room in the "penthouse" of a seperate building. We have a remote control in a rack in the studio we use to take readings and control the transmitter. AFAIK this set-up works well for us.