New Range Results for AM Ground Mounted System

I have previously reported a listenable range on a truck radio for my ground mounted AM system system as being 1 mile with fading at 1.3 miles. Today, while on an errand, I checked range again and it was solid listenable out to 1.8 miles on my truck radio and could be heard with flutter and noise 2.3 miles away (that's as far away that I drove). Though this is impressive for a part 15 AM system the actual range for in home listeners is not known but it is most probably much less. Someone with a good receiver and an outdoor antenna could probably receive the signal at two miles plus.

What has changed? Since my previous check we have had quite a bit of rain and the ground is moist but the field strength checked with my monitoring system hasn't changed. The other change is that I was previously using a modified Ramsey AM-25 but am now using my "high efficiency" transmitter which delivers 86 mW to the antenna system with 100 mW DC in. This doesn't explain the change in range however since the modified AM-25 delivers about the same power to the antenna system.

The other encouraging observation is that I have not tuned the antenna system in over a month and the field strength remains the usual so it appears to be stable.



RFB's picture

Wet ground means better conductivity, in turn will enhance the far field of the signal at those fringe areas (2 mile+).

The result would be the same if you could water down the ground in that 2 mile radius on a dry day when that signal would fade out at the 1+ mile point.

When it snows here, and we get a good bit of it, my 219 system will shoot 2.5+ miles, which for the size of Casper is fantastic. I would use that system all the time except it is sitting in a very limited space and I can't put down a decent grounding system, at least one that I would like to put down for it. But when it rains real good or snows, I fire it the CC system a well deserved break.


MICRO1700's picture

Neil, I think the range increase
IS because of the wet ground.

In my case, it was the opposite,
because the outside set-up was
built on the fly, and it would
get wet and detune because it was
never really completely finished
and protected from moisture.

It drove me crazy when the range
changed. Best range on my 15.219
system was 2.0 miles with the
SS-Tran 3000 and my improvised
coil system. At that distance,
the station was completely
listenable. About 70 or 80 "percent"
"quieting" (I know this isn't 2 meter
FM, but it's the best way to describe it.)
It was Q5. There were other times when
the signal did not go that far, and that
made me "nuts" too.

Oh,yeah, my field strength generally
remained the same, too, even when the
range changed. But sometimes, the
FS would be less, and the station
would go further.

RFB, at first I thought your 15.219 was
portable, but now I seem to remember that
it was made to look like something. Was
it a bird feeder? I still would like to
make a portable 15.219 system, but I
think that's a long long way off.

Best Wishes, and keep those range reports

Bruce, W 60 HZ
"Shocking Programming, now Saturday and
Sunday, 6:AM to local sunset"


12vman's picture

I bet the dormant trees have a lot to do with it. My range changed from ~1/2 mile to ~1.5 mi. between summer and winter. The only change was the trees.. (I have a bunch of 'um around here.)

The Mighty "T.H.C." Tunnel Hill Control.

Radiating Wild Animals with R.F. for Years!

RFB's picture

"RFB, at first I thought your 15.219 was portable, but now I seem to remember that it was made to look like something. Was it a bird feeder?"

No, I was describing a portable setup in a discussion about a mobile system and the issues of laying down a ground system for it. I've done it before and described it in detail. It's buried in the threads somewhere here.

The "bird feeder" thing comes from Carl's thought of putting a bird feeder house on top of a 3 meter stick with the bird feeder bottom being a capacitor hat plate. Again buried somewhere in the thread abyss.

My most favorite 219 setup was using a 10 foot tall, upside down aluminum Christmas tree with all of the branches but the ones at the top (bottom branches when tree is upright) removed to act as the cap hat.

Worked incredibly well over a 10 radial ground system. Sheesh that was YEARS ago!! (dusting off the cobwebs).


ab1aw's picture


What type of radial system are you using?


radio8z's picture


The radial system is comprised of 12 ten foot lengths of #12 insulated wire soldered together at the base of the transmitter and buried just below the sod.  At the center of the radials I drilled a 2 foot hole in the ground with a 1-1/2 inch auger and inserted a coiled length of bare copper wire to give a means to drain off static buildup.  This certainly is not a good RF (the radials serve this purpose) or lightning ground but I don't need more since the house is protected with the audio and power feed lines voltage clamped where they enter the house by means of a direct connection to the power line ground stake for the ground wire and spark gap arresters for the power and audio.  This has been in use for several years without problems with lightning nearby.

Here's a picture of the radials at a different location for testing and not buried.

Here's a shot of the loading coil and the final installation, the radials are beneath the mulch. This is at the edge of the yard with woods on one side and grass on the other.