So, now that IRC has been on the air for 10 months, and I pretty well know where it reaches, using my car radio, a small portable transistor set, and a boom box, and I've taken actual calibrated field strength readings with the same FIM I use in my "real" radio work, I thought I'd take a moment and map out just how far I'm reaching "as the crow flies" from my antenna. You can't really measure by driving away unless you can go in a straight line a measured distance!
So I used Google Maps and marked the spots where over the past months I ALWAYS get 100% full, loud signal, that is comparable to the two commercial broadcasters in my area -- the station I work for 5,000 watts about 8 miles from me, and a 10,000 watt station about 30 miles away. I can sit in the car in these spots and punch between those stations and mine and the volume and signal quality is about equal (actually I'm a bit clearer than the 10,000 watt station 30 miles away).
I have strong, reliable, static free sound at 7100 feet, about 1.35 miles from the antenna. this holds in virtually all directions. Remember, I'm in a VERY small town with very minimal interference. This gives me a circular coverage area of 2.7 miles diameter.
I can be heard quite a ways past that but the quality varies and I wouldn't expect anyone to listen to it with that much static in the background. At the 7100 foot line that's solid signal in the car, on the $5 portable transistor radio and the cheap boom box. Plus amazing sound on the GE Super Radio.
This is on the Procaster, using only the built in processing, taking audio straight out of my studio iMac right into the trasmitter.
I'm quite happy with that.
Tim in Bovey
...the station I work for 5,000 watts about 8 miles from me, and a 10,000 watt station about 30 miles away. I can sit in the car in these spots and punch between those stations and mine and the volume and signal quality is about equal.
From reading your posts and looking at AM assignments, I take it that the 5 kW station is KOZY on 1320 kHz, licensed to Grand Rapids, MN. FCC records show that it uses a single 100-degree tower during the daytime. The FCC M3 map shows a conductivity of 8 mS/m for that part of Minnesota, so the KOZY daytime, groundwave field at a distance of 8 miles should be about 24 mV/m.
Wouldn't you need to be a lot closer than 7100 feet from your Part 15 AM for its field to match that of KOZN?
I know you didn't report fields, just compared the listening quality on various AM receivers. But in an area with little r-f noise/interference the AGC action of the receiver could make your station sound about as loud and as noise-free as KOZY around Bovey, even though the two fields in/around Bovey would greatly favor KOZN.
Did you actually measure the fields from your setup and from KOZN at your range of 7100 feet, and if so, how did they compare?
Hey Tim, How is the Procaster mounted? Thanks.
I'm quite certain the evenness of the signal is directly related to the effectiveness of the AGC in my car radio. However, parked in the same spot I also get out of the vehicle and listen on a boombox and a $5 portable radio -- one of those little handheld jobs, and still find IRC to be just as listenable as the big guys. Or course I have to rotate the radio for best signal.
I have not taken FS readings for KOZY at this spot, I have for IRC but I'm not at home and don't recall the reading off hand. But I'm sure KOZY will be a ton stronger. But in practical listening comparesons all three sound about the same.
Tim in Bovey
That's pretty amazing. I too would be interested in the installation details of your transmitter (i.e., ground mounted? type of ground? radials? etc.).
I'm also jealous.