phone line protection, Radio World

[emrr]

love this DIY

https://issuu.com/futurepublishing/docs/rwm1245.digital_ns/12

 

[JohnRoberts]

should not be as much of a problem with modern gear.

I recall losing one TV set from lightning coming in a cable TV connection.

JR

 

[emrr]

Yeah, I was wondering how many landlines are still in use anyway.

 

[JohnRoberts]

Yeah, I was wondering how many landlines are still in use anyway.

I still have a land line but it doesn't use hard wire POTS (plain old phone service) any more. Now the phone signal comes from the DSL modem. I have a switch on it so when I get too many robocalls I just switch it off for a few days. The DSL carrier goes through the old phone wires.

JR

 

[user 133392]

AM sites often use POTS lines for remote control particularly return path telemetry if the studio transmitter link is unidirectional. Remote control commands to the transmitter are often on an STL subcarrier or STL aux data channel. FCC regulations require the transmitter to shut down after a time-out if remote control or telemetry is lost so that POTS line becomes a critical circuit.

Stations whose transmitters are co-located with the studio are particularly prone to lightning travelling over the STP from the transmitter hut into the studio. There's still a lot of REP-111s being used on those dry-pair tielines for galvanic isolation.

WRT to lightning Ethernet ports can be very fragile. I highly recommend CAT-5/6 arrestors on any device connected to a copper-based carrier.

 

[user 37518]

When I was young (back in the days of Dial Up Internet) I had to buy a phone line protection circuit after two modems died due to lighting. After my first modem died (I remember how it happened, it was raining, a flash of lightning stroke and the internet connection was immediately gone), I saved up all of my money during more than a month to buy a 56K US Robotics modem, which I considered as the "Rolls Royce" of modems and was quite expensive; it lasted for like a week before lightning stroke again somewhere, God knows where, but the induced spike on the line was enough to fry the modem. My mom felt really bad about it and bought me a new one, along with a phone line protector. No modem fried after that. Thanks, mom!