[BC] Telco and the program loop

[Broadcast List]

I was on the way to the Transmitter site and heard the audio drop in  
level (company car, NO RADIO, portable radio on the seat), and KNEW  
we just lost a channel.  Heard it come back, then drop again.   
Thankfully, my assistant and I were only blocks away.  We ran inside  
and discovered out two sets of stereo conditioned pairs doing weird  
things.  We kept having to switch pairs, and flip the patch cords to  
keep the station in phase.  We then lost three out of four circuits,  
and went to a "Y" patch cord we had made.  Left-e-o and Right-e-o  
beat the heck out of what was going on.

I couldn't get Radio Center to do anything, so since I knew where the  
last CO was, I figured what the heck.

I followed the overhead wires as the bundles kept getting bigger and  
bigger.  Then the cables went under-ground.  Now it was best guess.   
Close to the CO there was a tent over a manhole and a C&P Telephone  
truck.  I stopped, entered the tent only to hear the station playing  
loudly out of the manhole to a HUGE vault..  I asked him how he was  
getting that music under-ground and he pointed to a test set.  I  
asked him to get the hell out of our circuit and call Radio Center.   
He didn't have a clue was I was talking about, but I gave him the  
number and went into the Pizza Hut to use the pay phone.

It turns out they were moving circuits around in order to abandon an  
under-ground cable which was in the way of an interchange that was  
going to be built.  I had a conversation about half-tapping with the  
jerk in the vault, and a conversation with Radio Center about  
protective caps on our circuits.  We had a lot of bridged circuits  
and our cable had a LOT of houses dial tone on our cable at both the  
studio and transmitter sites.

At that same station we had MANY very inexpensive alarm circuits for  
telemetry and some other uses, plus to use as a doomsday program feed  
backup.  Outside plant guys would see a pair that had nothing on it,  
and steal it.  We would go to use one of our pairs because some other  
circuit quit, only to find dial tone on the pair!

We tested the circuits often so we kept getting them back.  In the  
end I found we were allowed up to 250 Volts DC that was current  
limited by the loop resistance.  I'll bet you can't guess what came  
next!  We put 250 VDC on the circuits at one end, and -- I don't  
recall the exact Voltage at this point -- but something like 48 or 12  
Volt bulbs on the other.  We fed some from the transmitter, and some  
from the studio so we could grab one and put equipment on it instead  
of the power supply depending on the end we were currently visiting.   
We didn't filter the power supplies well so they would produce  
several Volts of HUMMMMMMM.  Needless to say, they stayed out of our  
dry pairs!  The funny thing was I had a hard time keeping the  
protective caps on our 66 blocks until I put that 250 Volts on the  
pairs but not after!

--chip

On Jan 3, 2008, at 1:49 PM, broadcast-request at radiolists.net wrote:

> Message: 30
> Date: Thu, 03 Jan 2008 09:13:18 -0700
> From: "Ron Nott" <ron at nottltd.com>
> Subject: [BC] Telco and the program loop
> To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
> Message-ID: <7.0.1.0.2.20080103091234.065abe70 at oldradio.com>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
>
> In ancient times, Collins sold a turnkey package of a new Class A FM
> in a small town in SD.  The GM had wheedled an audio proof from the
> Collins salesman, so he and I began running it at midnight.  Soon it
> became obvious that there was a big dip in audio freq response about
> 1 kHz.  Naturally, the GM blamed the new equipment, so I ran a quick
> check on the transmitter to prove that it was good.  Then he blamed
> the console, so we checked and it was good.  I said, "Lets do a proof
> on the AAA phone line" to which he resisted, but finally
> consented.  We found a dip of about 10 dB near 1 kHz. The GM then
> went to the phone company where a small crew was working in the
> shop.  The station was to simulcast the AM & FM, so the audio was on
> a common line (yes, the GM was cheap).  He learned that for years,
> the shop crew had hung a 4" speaker across his 600 ohm line on clip
> leads to "listen to the radio" in the shop.  When the speaker was
> removed, the line was good. I advised the GM to buy a cheap radio and
> give it to the shop crew.  He had never noticed the effect on his AM
> signal, but noted that the quality improved after the speaker was
> removed (DUH!).
>
> Ron Nott, DVP