broadcast man

Thanks for asking.

I haven't had much time to work on it.

I did try adding 5 radials in the position it is in and then retuned it buy it did not help. I think I do need some help with tuning, though.

I am going to move it as soon as I can to the center and put in some radials and find someone to help tune it, and if that does not work, I don't know what I will do, as I was expecting a lot more than I am now getting.

Broadcastman,

I'm sure many are interested in the effect of an elevated ground plane. Hope you can report some definitive results soon.

I vaguely remember your original post about your elevated antenna but can't easily locate it. You mention you may have a tuning problem. This triggered a sensitive spot. I get the impression that many part 15 enthusiasts don't quite grasp the importance of tuning an antenna. I'm not saying this about you! Just siezing the opportunity to disseminate a little info to everyone.

Short vertical antennas (this is the terminology for our part 15 restricted crippled antennas) have by their nature a very sharp tuning peak. If they are tuned just a little off frequency, range will drop dramatically. The tuning peak is similar to what you experience with an analog-tuned AM radio receiver. As you turn the dial, the signal peaks and then goes away quickly. Likewise, if you don't tune your antenna to its absolute peak, your range will go away quickly.

Because each transmitter user has a unique installation with respect to height, ground and who knows what, tuning is unique for each installation. Any deviation from the manufacturer's recommended installation can cause tuning problems.

You absolutely MUST tune to the pronounced peak as indicated by your transmitter's meter output or by a field strength meter reading. If you don't get that pronounced peak or you get some sort of gradually rising reading, but not a peak, something is WRONG. Go no further. Fix whatever is wrong with your installation before proceeding.

Thanks for asking.

I haven't had much time to work on it.

I did try adding 5 radials in the position it is in and then retuned it buy it did not help. I think I do need some help with tuning, though.

I am going to move it as soon as I can to the center and put in some radials and find someone to help tune it, and if that does not work, I don't know what I will do, as I was expecting a lot more than I am now getting.

Phil has a very good point. And I'll add to that, since he brought it to my mind.

Your hand, even body, capacity may affect the tuning. After you peak it, get back and, using binoculars if necessary to read your meter, see if the peak dropped off. If it did, you'll have to hunt for the spot, either side of the peak, which will peak when you back away from the antenna.

Keep the meter and its leads as low a profile as possible, too.

Those with their antennas grounded to a support structure shouldn't have a problem with this, providing one stays below the antenna's base as much as possible.

Bill in SE Texas

I wrote: << Your hand, even body, capacity may affect the tuning. >>

I just remembered... I had that very problem when I was bench testing (on my kitchen table) the AMT3000. And I was using a long nylon tuning tool, too.

The "antenna" was the supplied ten-foot wire, stretched out off the far end of the table from where I sat.

Bill in SE Texas

Checking back in with you about this.

I put this project on hold, but am hoping to get things going again within the next couple of weeks.

I do not think I ever got a true "peak" in my readings. Just a gradual rise and not much of an increase.

I don't know much about this beyond what they tell me in the Hamilton directions. I did have an engineer help me with the first setup, but I did not get the range I wanted and have since done a lot of tinkering with it.

I'm going to move everything to the center of the roof and put in ground radials.

The tuning part will then be the trick because I really do not know if I am doing it right.