Although local channels are kind of a lost cause for DX purposes, I am curious to know what people have noticed in the way of differences in propagation and interference levels between the lowest and highest local channels. Is 1230 noticeably better for daytime coverage? Does 1490 have a lot more interference at night?
-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
Propagation and Interference Differences between 1230 and 1490
- Thread starter audioguy
- Start date
You tend to think of 1230 as almost a low dial position because of the Clear Channels right below it, and 1490 as a high dial position because of the Clear Channels right above it. The NIF of particular stations depends on each individual station and the milieu of other nearby stations. There are slight differences. Because I used to live in an area with a station with a great groundwave in the high 1400s, I usually think of the high frequencies beginning at 1500. I guess the station was in a sweet spot for site conductivity.
If your state has a Quaternary Geological Survey Map, you can predict where those sweet spots are better than M-3.
If your state has a Quaternary Geological Survey Map, you can predict where those sweet spots are better than M-3.
Some comments that parallel this discussion. From my experience, the ground wave performance of the class C “graveyard” stations can vary a lot depending on their location and transmitting facility. I’ve not seen any real difference in how a 1230 performs compared to a 1490, if they have similar facilities ie: same power and same tower height. On paper, the 1230 should be a bit better.
I’ve never worked in an area with good ground conductivity. With a lot of water nearby, here in the coastal area, we do get some stations much farther than normally over land due to the water path. I’ve been told by other engineers, in some parts of the mid-west, the Class C stations do very well compared to those here on the east coast and can be heard, with a listenable signal, out to 100 miles or more during the day.
Many years ago, I was the CE of a station on 1450 that operated with 1000 watts into a 400 foot tower. This is pretty close to the ideal height at around 210 electrical degrees for an AM radiator, and the station had a good daytime signal considering the frequency and ground conductivity. It also was fairly strong at night within a few miles to the city of license compared to similar stations.
We have locally a station on 1240 with a short 81 degree tower. Their daytime signal starts to fade at maybe 20 miles and at night, they are sometimes receiving interference at 5 miles.
Most of the old class IV stations, now class C, were put on the air many years ago to serve a local area. Many were also low budget operations and building a station with an inexpensive tower below 200 feet kept the construction costs low and usually required no or minimal tower lighting and may have not required regular painting to meet FAA (or CAA) approval. The 620 watt flashing beacons on a tower eats up electricity and requires periodic replacement and wiring repairs.
Just some thoughts. Bill
I’ve never worked in an area with good ground conductivity. With a lot of water nearby, here in the coastal area, we do get some stations much farther than normally over land due to the water path. I’ve been told by other engineers, in some parts of the mid-west, the Class C stations do very well compared to those here on the east coast and can be heard, with a listenable signal, out to 100 miles or more during the day.
Many years ago, I was the CE of a station on 1450 that operated with 1000 watts into a 400 foot tower. This is pretty close to the ideal height at around 210 electrical degrees for an AM radiator, and the station had a good daytime signal considering the frequency and ground conductivity. It also was fairly strong at night within a few miles to the city of license compared to similar stations.
We have locally a station on 1240 with a short 81 degree tower. Their daytime signal starts to fade at maybe 20 miles and at night, they are sometimes receiving interference at 5 miles.
Most of the old class IV stations, now class C, were put on the air many years ago to serve a local area. Many were also low budget operations and building a station with an inexpensive tower below 200 feet kept the construction costs low and usually required no or minimal tower lighting and may have not required regular painting to meet FAA (or CAA) approval. The 620 watt flashing beacons on a tower eats up electricity and requires periodic replacement and wiring repairs.
Just some thoughts. Bill
N4GBK said:
Yup...here's one on 1230. Thief River Falls, MN-KTRF. Clearly audible daytime in Winnipeg, about 125 miles away. http://radio-locator.com/cgi-bin/pat?call=KTRF&service=AM&status=L&hours=U.
cyberdad said:
I can remember listening to Columbus' WCOL (1230, now WYTS) about 100 miles northwest in St. Marys, Ohio several years ago. That was despite Toledo and Cincinnati also having stations on 1230. Reception wasn't great (maybe 2 out of 10) but it was there. And that same signal makes it to my home now, about 30 miles east of Columbus, at night, although it is extremely weak.
By the same token, a 1240 from about 23 miles east of me, in Zanesville, Ohio, has no prayer of making it here after nightfall. WYTS runs 1,000 watts; WHIZ runs 960 at night. I think the only difference is the poorer ground conductivity to my east.
Probably only marginal vis-a-vis the discussion, but on car trips between here (near Halzeton PA) and my old stomping grounds in NYC I was able to take WEEX 1230 way farther east through north Jersey than I could with WEST 1400.
Both stations are licensed to Easton PA. And oddly, WEEX 1230 is a rarity (a directional graveyarder during the day) which sends its juice kind of north-south, not east.
* * * * * * *
Question for you folks : When were the 'class IV' stations allowed to go to 1000 watts day?I believe it was a different, earlier year than when they were allowed to go 1000 watts around the clock .....
Both stations are licensed to Easton PA. And oddly, WEEX 1230 is a rarity (a directional graveyarder during the day) which sends its juice kind of north-south, not east.
* * * * * * *
Question for you folks : When were the 'class IV' stations allowed to go to 1000 watts day?I believe it was a different, earlier year than when they were allowed to go 1000 watts around the clock .....
From a quick Google and fuzzy memory search. Daytime class IV upgrades to 1 kW began around 1960. Nightime upgrades to 1 kW started in the early 1980s. Some stations were restricted to lower powers due to signal overlap with adjacent channels etc. I remember some Texas stations near Mexico were still 100 watts fulltime when just about everyone else upgraded. Also, I think some of the 250 watt day/night stations chose not to increase their power back in the day as they would have to buy a new transmitter and upgrade the antenna tuning unit and they covered their small town just fine with what they already had. Many years ago, a station licensed for 250 watts fulltime could not use a 1000 watt transmitter at reduced power. I remember seeing some of the old 1930s and 1940s vintage 250 watt transmitters were still around at some small town stations in the 1970s. Some were ready to go as auxiliary units.
There were once seven stations that were Class IV and directional daytime only, U, DA-D or U5 to use FCC and WRTH DXer terminology. WEXL Royal Oak, MI and WLEW Bad Axe, MI are two. Daytime use is not permitted, although it seems there could be some special cases where it wouldn't a problem, like changing TL without reducing power, to maintain the same service area.
"Daytime use" in the above post should read "nighttime use".
Thanks everyone for the interesting comments! We do have a Class C in Chicago (I still think of them as Class IVs)-- WSBC (1240)-- that makes it ~75 miles east to the South Bend/Elkhart area in the daytime. The other Chicago graveyarders die out very quickly and some don't even cover the entire city (thinking of 1450 in particular).
As a boy, I remember going through Thief River Falls and listening to KTRF on the car radio for a long way, although I don't recall how far. Another Class C I remember was KLTZ in Glasgow, MT. I think they had a sign posted about 75 miles out of town to tell people to tune in!
As a boy, I remember going through Thief River Falls and listening to KTRF on the car radio for a long way, although I don't recall how far. Another Class C I remember was KLTZ in Glasgow, MT. I think they had a sign posted about 75 miles out of town to tell people to tune in!
- Status