Signals

[Clayman43130]

Does someone know why (for example) 610, I can hear wtvn all over ohio during the day and at night I hear static in Lancaster as if it is a weak signal. It was explained to me once that they drop power at night.

Why do stations have to do this at night?

 

[w9wi]

Does someone know why (for example) 610, I can hear wtvn all over ohio during the day and at night I hear static in Lancaster as if it is a weak signal. It was explained to me once that they drop power at night.

Why do stations have to do this at night?

WTVN isn't required to reduce power at night. (though many other stations are, including WBNS which reduces from 5,000 watts to 1,000)

However, WTVN is required to switch to a directional antenna. I don't have their directional pattern handy but I'm pretty sure they're protecting stations in Philadelphia and Kansas City that were on 610 first. Of course, Lancaster is between Columbus and Philadelphia and I'm sure you're in the middle of WTVN's nighttime null.

Unlike FM, AM stations "get out" a lot better at night than they do during the day. An atmospheric layer that allows AM signals to "bounce" great distances is blocked during the day by another, lower, layer. At night, this blocking layer goes away. If WTVN were to operate non-directionally at night, its signal would "bounce" into the Philadelphia and Kansas City markets and clobber the stations there. (yes, an Ohio station is fully capable of causing harmful interference in Kansas City.)

WTVN hasn't been on 610 that long in AM radio terms. Going into World War II, they were a "limited time" station on 640KHz, (then known as WHKC) allowed to sign on the air at Columbus sunrise and remain on until the sun set at the "dominant" station on 640 -- KFI in Los Angeles.

At the end of the war, WTVN was authorized to move to 610 and operate 24/7. However, since WIP Philadelphia and WDAF Kansas City had been on 610 since at least the mid-1930s, WTVN had to protect them from interference.

 

[schmave]

WTVN's directional pattern is outstanding. Having worked at the Lancaster newspaper for five-plus years earlier this decade, some of those shifts lasting until well after midnight, I had plenty of experience coping with WTVN's nighttime signal. Lancaster actually gets 610 a lot better than some other areas of central Ohio, probably because it's just south of the very deep null toward Philadelphia. Forget about hearing it in or near Baltimore or Millersport at night.

Driving home from Lancaster to Pickerington, there were two spots where I would lose 610 almost completely: The intersection of 33 and Lithopolis Road in Carroll, and on Hill Road right by Pickerington H.S. Central. The second was smack in the heart of the eastbound null, and while 610 never completely faded it came darn close.

The westbound null toward Kansas City is equally impressive.

The flip side of those nulls, of course, are an excellent signal to the north and somewhat decent coverage into some southern areas. I personally have heard 610 all the way to Chillicothe at night to the south and Mount Pleasant, Michigan to the north.

I'm sure some reading this will remember when WTVN went non-directional at night for several weeks back in the summer of 2004. There had to have been some interesting DX pickups and maybe some aggravated people trying to hear 610s.

 

[alans613]

I remember picking up WLW once in Georgia in the middle of the night on my Walkman many years ago.
Thanks for the explanation on this topic...I have often wondered about this myself. 8)