1.5 to 2 Mile Range Possable??

Under ideal conditions at the transmitter and especially at the receiver the AM range can be 1 to 2 miles.

I operate a home brew high efficiency transmitter which delivers 86 milliwatts (with 100 mW input) to a base coil loaded vertical antenna mounted at ground level with 12 ten foot radials which gives a range assessed with a car radio of 1.3 miles for a listenable signal.

I have heard a "Talking House" signal from over two miles away using an outdoor dipole and a communication grade receiver which is not the typical setup for an AM listener.

This being said, it is unlikely that such range will be had with the typical indoor AM receiver due to the poor antennas used and the electrical noise which interferes.

Neil

With my previous Rangemaster, the signal was listenable to about 1.5 miles, but it was directional, mostly east and west. North was less, and south is private land, so I was never sure.

Best reception report was 7 miles, with a Cunningham transmitter on 1160.

Your range depends on a number of factors, including (but not limited to) the sensitivity of the radio on the receiving end, the antenna at the receiving end, and obstructions.  I was able to get a listenable signal out about 2 miles over open ground, with a wire antenna and a Talking Sign transmitter (the wire was held vertical by a piece of PVC pipe).  But in any other direction the range was 1/2 mile or less (these were built up areas).

Best reception report was 7 miles, with a Cunningham transmitter on 1160.

Unfortunately, such comments might set up unreasonable/risky expections for unlicensed "Part 15 AM" operators thinking they are complying with FCC §15.219 -- and even for a useful/consistent coverage radius much less than 7 miles.

Another factor affecting range is the local electrical noise level. Often noise level varies widely over the circle of desired range. If you're in a rural area, electrical noise may not vary much, but in a typical medium density suburban area it can vary a lot.

Consider a desired coverage area that has rural, sparsely populated area in one direction and a denser commercial area in another direction. The commercial area will have higher electrical noise interference, which will make your signal seem weaker in that direction due to the receiver AGC (Automatic Gain Control) reducing receiver gain in response to the higher electrical noise.

Car radios have very good AGC action making it impossible to judge if your signal is weaker or the noise level is higher. This can result in the illusion that your signal is weaker. If you could disable the AGC entirely, you would get a better judgment of your signal vs. the noise level

AGC is also the reason why there is the illusion that your signal is weaker at night. In fact, your signal is the same strength at night, but your car radio AGC is reducing its sensitivity in response to the increased skip signals. Even if there is no identifiable single station skipping in, the general level of combined signals from multiple stations is causing the AGC to reduce gain.

Good point Phil.

So - from a non-radio-tech (me), regarding range... I was over in Half moon bay this weekend, and while there, I tuned in to a station that is running from at least 2 rangemasters (its what we could see when we drove through downtown).  16 miles away you could bare make out the music playing.. I mean like.. you knew it was there, but it was just a steady stream of background music that you cant really make out.  It seemed like the second we hit the "Now entering Half Moon Bay" sign coming up from Santa Cruz, the signal was just "boom" right there. perfect clear sound.  As we left heading out HWY 92 towards San Mateo, the signal faded pretty quick.

My setup has been SSTRan AMT-5000 (best range), Procaster (awesome sounds, great range), and Talking House with ATU (great range, sound really is not awesome).  With these setups, NONE of them got any where near the range the HMB system was getting.  I can make out that there is sound at about 4 miles.  At 1.5 miles its crazy static, but a bit louder on the music side, at 1 mile its good enough to listen to, but still static, at .75 the sound becomes stronger, and the static fades fast. At .5 miles its near perfect, then at 1 block away, there is noise - but i think that has to do with the neighborhood power lines.

In manteca, CA my setup was the Gittings 100mW with the Manteca Magnum antenna, and on a great day, you could actually get some audio from modesto to stockton.  On a crappy day, you couldn't get the other side of town.  And its was a much smaller town 10 years ago.

In San Jose, I got a solid mile using the early version Procaster.

I did use a Rangemaster at one point, and if I wanted to go with a cluster, I would probably do this again.  

Right now, its the procaster as the primary, and the talking houses as fillers around town.

My last good set-up was an AMT-3000,

a "less than 3 meter vertical/ground lead,"

and 16 ground radials.  So it was a stick

in the back yard ground mounted.  

Our downtown area was about 1/2 mile

away, and downtown was maybe 2/3s mile in 

diameter.  I think.  My friend had a very very

good car radio.  He could listen to my

station all over the downtown area, and

in his driveway about a mile away on the

other side of town.   Reception

was good he said.  At least during the day, before

critical hours and night - when 1690 kHz got

cluttered.  I heard the station clearly with not 

much noise on my wife's car radio in a parking

lot about 2 miles away from my transmitter, 

but that was a "hot spot."  Driving around

in a car will tell you that your coverage

area is never a circle.  There are peaks and

nulls, and mysterious areas where reception

is very good - and then other areas where 

reception just goes away for no reason, seemingly.  

Car radios are easy, indoor radios are much 

harder, in terms of reception.  On our street

our lots are narrow, maybe about 80 to 100 

feet wide.  About 8 houses away, indoors, my station

was received on a boombox of unknown sensitivity,

with about 70 percent signal and 30 percent noise -

as heard through the telephone.  They had called

me on the phone.  If I had been there I could have

rotated the radio or moved it around and looked for

hot spots.  In the other direction, about 6 or 7 houses

away, in the house, in the kitchen - reception was

almost noiseless on 1690 kHz, during the day - but

on a very good radio - a GE Superadio 3.  (I was there.)  

The town park was about 1/2 mile away.  Reception 

in the park on a picnic table was about 80 percent 

signal, 20 percent noise, on a Grundig S-350 portable.

(Not a Grundig S-350DL - the S350 was an 

earlier model - for you Grundig dudes.)

I also have a vintage 1960s pocket radio -

which I monitored while walking around

some of the back streets of my neighborhood.

This was a fair to good (?) radio.  I heard my

transmitter back 2 or 3 streets parallel to my

street.  (Outside.)  That's the best data I have for my

Part 15.219 installation, which was eventually

turned off for repairs.  

I hope this helps.

Bruce, DOGRADIO

KDX Worldround Radio signs off from about 8 PM to 10 AM CDT, except Friday, Saturday and Sunday nights when we stay on all night.

Everynight after dark a noise suddenly starts up on the X-band, and sometimes it's louder than others. It's a 2-minute sparking noise that always starts softly, grows louder, until it's very intrusive, like an electric shaver. But all of a sudden it switches off for awhile and things are quiet.

I have watched the turn on of things like street lights and peoples porch lights, but have not spotted an obvious source of the noise.

Sometimes I wonder if it's something in the house, but it acts like a signal from the distance. If it was in the house I think I'd hear it all day.

Some night I'll creep around out there and track it down.