hey gang.
I had my TH ATU on the roof of my house as many of you know.
However with the SS Tran5000 EX I want to put it on the ground for many reasons.
So I am linking this video to show you what my issues are with ground mounting this system and I want to ask Neil and Rich and Mram and Carl or any of you what you think is better.
In the video I show the wires that are near me and all of the trees and such that are very close.
My idea with the roof mount was to get over all of this stuff.
But as I have been reading over the past few weeks I have seen where people say that it works better than the roof mount with no ground wire or even just one gound wire going to the grounding rod in the earth.
So please take a look at the video and let me know what you all think is better in this case.
Lefty - From your video it appears that the location you're thinking of has fairly decent clearance from neaby objects. A ground-mounted SS-5000 transmitter using a 3-m whip and a short conductor from its ground terminal to the common point of a set of buried radials under the base of the whip would give you about all the coverage you can expect from a system meeting §15.219. I'd suggest using at least 12 buried radials with equal spacing, and to make them each about 15 feet long, if you can.
But you may find that coverage from this ground-mounted installation will not be as good as it was from a roof-mounted system, if that roof system had a lot of radiation from wires connected to it, and/or the vent pipe.
Rich what I am hoping for is that the 5000 with it's 98 % efficiency will get out better than the talking house ATU system with only 80 % audio. The 5000 will do 100% audio with no help from compressors. And it has the 98 % power at the Antenna . That is my hope anyway .
Rich thanks for the info , it really is nice of you for the help.
From everything I know, the Medium Wave Band, the AM band, operates by GROUND WAVE.
I have always understood this to be a radiated wave traveling across the ground, right at the top of the earth's soil.
Other bands, like the FM band, do better with high antennas because they are more like light bulbs which can be seen better the higher they are.
I also know from experience, that medium (AM) waves flow around objects the same way as water. Another reason to keep them low down on the ground.
I think putting AM antennas up high should only be done when there is no other choice.
Many thanks Carl
Also guys I uploaded a better version of this video to help see what wires I am dealing with .
The 5000 ... has the 98% power at the Antenna.
Sorry, Lefty, but the ~98% efficiency expected for a Class E AM transmitter does not mean that the carrier power at the antenna will be ~98% of the 100 mW power limit permitted by FCC §15.219.
The FCC limit applies to the d-c input power legally permitted for the final r-f amplifier of an unlicensed AM transmitter. But other system losses need to be accounted for. Even if those losses are rather moderate, this can result in a radiated power well under 0.5 mW for a 98% efficient transmitter meeting §15.219 (as shown in the clip below).
It can be true that an optimized Part 15 AM system using a transmitter with a Class E r-f output amplifier might radiate 2 or 3 times more power than some other systems, other things equal.
But the improvement in useful groundwave signal at a given distance from that Part 15 Class E transmit system will increase only by the square root of the increase in radiated power.
Even in the case where the transmitter itself is 98% efficient and other losses are moderate, the field at a radius of 1 km (about 0.62 miles) from such a system meeting FCC §15.219 is getting rather marginal for a typical, indoor AM receiver.
The clip below shows the details...
See my edited post below.
Point taken 🙂
Rich the old TH AUT with no ground and cable tested for radiation fell under 209 .
It transmitted more than a mile in two directions , east and west .
So what I hope will happen under these parameters is that the 5000 with a proper ground will go more than one mile with a car radio.
That is what I am looking at for my hope of transmitting range.
I plan to use at least 20 radials or ground leads for the system.
Not sure I can go as far as fifteen feet as the yard is rather small for this sort of thing 🙂
I will be doing video updates of the project as it moves along over the next few weeks.
Also transmitter site two will go live in about a month . There will be videos of that site as well.
One more thing .
If it is .62 for home based radios , that would be good .
Rich thanks Sir for the help .
I love this Part15.us place.
Rich the old TH AUT with no ground and cable tested for radiation fell under 209. It transmitted more than a mile in two directions , east and west.
The field limit permitted by FCC §15.209 for an unlicensed AM station on 1610 kHz is 24000/F(kHz) = 14.81 µV/m, at a distance of 30 meters from the radiator.
A MW field of ~15 µV/m is below the ambient noise level in most places outside of a screen room.
So if that TH system produced signals with useful S/N ratios at a mile or two, do you think that it actually met FCC §15.209?
Yea it did 🙂
I think the old ATU may have been taking a ride on the zillions of wires around here.
At my old house a TH with it's wire antenna shocked many of us by how far it got.
Again I think it was acting with the wires out in front of the house as the antenna was in the front room with a window right next to it and it was a 180 year old house with nothing but wood in the walls.
The effect of the wires has been on my radar ever since then.
I am starting to think if we used the power wires in our antenna scheme we would learn lots from it . I really think that is part of what made my ATU work so well.
In truth I would have stayed with the TH is it could handle more than 80% Modulation .
I'll refrain from further comments in this thread.
Joe, as you most likely know each installation is different and thus the results may vary but it appears that your site is a good one for the install you described. The buildings and trees should not be a problem.
If you use THIS LINK and are patient enough to follow the links in the threads you will see the details of the installation and test results for my system.
My transmitter is a home brew unit which provides 86 mW output to the antenna system and uses a base loading coil at the antenna. The difference is that the AMT 5000 has the loading coil integral to the transmitter but the performance of these should be comparable.
The most critical thing is to make sure the antenna system is resonant. Resonance is very sharp and is easy to miss.
Based on my experience and providing the background noise level is reasonably low you should easily get 1 "car radio" mile range and maybe more.
Neil
Edit to Add: In case you missed it here's a photo of my antenna being inspected and another view.
Thank you very much Neil.
I am about to start the reading 🙂
Rich, ever wondered why the FCC still uses "input power" on Part 15 AM and "output power" everywhere else?