New Antenna Build for KDX
Plans are reaching completion to install a long awaited outdoor antenna structure for KDX-AM.
To be located 100-feet south of The Internet Building, home of KDX Worldround Radio, we will install ground radials slightly below the surface of earth and a 3-meter vertical antenna separated at the ground by a transmitter building, which will be a small circular structure sufficient to accommodate an engineer standing upright with the transmitter electronics at a convenient 39" above floor-level for easy access and removal from water and snow at the ground.
The walls of the circular-building will be lined with screen to achieve an anechoic-chamber effect equivalent to being under the ground. About 9-feet of ground-lead and transmission line contained within the building will be considered buried thus not counted toward the lengths specified in 15.219.
Even at that, we estimate that 9-feet of ground-lead under any circumstances would contribute so little to affective range as to be inconsequential.
Increased range is of no interest to KDX. The purpose of the outdoor installation will have three justifications:
The owner-listener, myself, wants to hear the signal from a DX perspective coming from the distance especially at night.
Second, the tower will serve to accommodate other antennas and electronics connected with other projects.
And third, we view this as experimental and intend to share the results with readers here at this Forum.
We request that the whistle-blowers who report our intentions please notify us so we'll be properly attired for the inspection.
It is neat to have a transmitter remote from the studio as you have proposed. I have done this and understand.
But, I am not sure of the design you propose in terms of what you are wanting to achieve. Why not just mount the transmitter at ground level with the attached antenna base also at ground level?
Your "anechoic" chamber is not likely to work as you may think so you could spare yourself a lot of effort by not pursuing it.
Neil
The Reason
Upon being asked: "Why not just mount the transmitter at ground level with the attached antenna base also at ground level?"
A weatherproof box (containing the transmitter) located at ground level is at risk of water, ice and snow exposure and certainly would not be convenient when it comes time to make adjustments, exposing the technician to shock hazard from himself being on wet ground or in the dark or cold.
Full power stations don't build boxes around their transmitters with the technician standing or crouching outdoors and we shouldn't be expected to make that kind of risk over the matter of a few feet of extra wire (ground-lead).
The "anechoic chamber" of course won't perform at 100% efficiency, but it will diminish the amount of minuscule radiation that escapes which, as I said, will be inconsequential.
Then also is the matter of security. The transmitter will be more more protected by being enclosed, and the small round shed can also house other equipment associated with the array of devices planned for the small tower.
The whole idea could collapse if local ordinance prohibits building small round structures, in which case I won't know what to do.
Further Study
Here inside the Internet Building we have an AMT3000 SSTran Radio Transmitter located on the floor under the corner of a desk connected on its topside to a Wintenna... a wire running up to a metal window frame and additional wire at top to achieve 3 meters vertical...the transmitter ground running down the baseboard and clamped to the building's I-beam.
To access this transmitter for tuning mere crouching is insufficient... it requires being on the floor on all four with only one hand free because the second arm is needed to keep from falling face down. The same awkwardness would exist with a ground install outdoors.
A crouching position would necessitate raising the transmitter to about 14" above ground.
Kneeling would be unsafe, the knees exposed to damp earth would pose a deadly shock hazard.
At one time I tested the transmitter with a 20-foot antenna held vertical by a bamboo pole, then compared the reception with a 10-foot antenna and could detect no discernable difference in range.
I would be amazed if such trivial factors are really worth fussing over. It seems juvenile.
I suppose that this approach might be successful as long as FCC field inspectors are able to be convinced that the situational ethics/needs of operators supersede FCC Rules for Part 15 AM.
We Must Live in Present Day Reality
Rich says: "I suppose", and indeed it is Rich doing the supposing.
In this reality the Schutzstaffel are long gone and I hear that FCC people are quite reasonable.
What I have postulated is hardly defiant, based on good reason and would cause no interference.
What I have postulated is hardly defiant, based on good reason and would cause no interference.
It's no more defiant than what the norm and accepted methods of installing part 15 AM has always been.
New Developments
In a competing forum Rich Powers is entrenched in a perpetual thread comparing ground mounted to pole mounted antenna installs, and said: "It just seems a more reasonable approach than installing a transmitter just above the dirt, because such would invite a whole slew of potential problems. A ground mount I think is an act of desperation to insure 3 meters, and is really borderline ridiculous to me."
So I'm not alone in finding the "conventional" ground mounting of a transmitter to be a ludicrous and reckless idea and henceforth reject such a plan as being nonsensical.
At the same time I'm dispensing with my thought of building a circular transmitter shack underneath the antenna as being badly over-proportioned. As it happens the location for this project is within a semi-forested garden area and would best be a very slim profile, with the final solution comprised of a transmitter raised high enough to be out of easy reach for the casual vandal but reachable from the first or second step of a ladder.
Never again will I bring my plans here for comment so long as a play acting enforcer recites his distorted extremist rendition of an FCC inspector from hell.
May your ground lead be a short stubby runt.
You could run your ground lead thru a mud hut and install it on top!
"Small round thatched mud hut in Perth zoological garden Western Australia.."
Got Mud?
That's a BEAUTIFUL thatched mud hut and could even accommodate beds!
We've got some mud and thatch and even beat-up wood for the door!
Rich Powers, we will name you as Executive Architect of the new KDX Tower Building!
I've mentioned before that I'd like to build a tiny house on wheels, not a big one like a lot are doing now, but maybe an 18 to 20 foot one. Rangemaster mounted above the porch and a small corner inside somewhere dedicated to the studio and equipment.
But a extra small type thing could be used for your idea. For example, the description is lacking, but this appears to me to be an 8 foot trailer with a fold down porch..
"This tiny house on wheels was located on a camp site in Winslow Memorial Park in South Freeport, Maine."
Or you could more elaborate:
"My Darling Tiny House on Wheels
by Marsha Cowan (North Carolina)
I bought a 14' trailer, but because of poor construction, had to build a 10'long house instead which meant really changing the plans, but now that I have it, I absolutely love it. It is built mostly from scraps, bargains, and recycled materials including old 100 year old stable boards from which I pulled a gallon bucket full of old rusty nails. The boards were used for the outside and inside of the home and add a very warm rustic feel against which I put a lot of white trim and furniture. There is a composting toilet. I worked on the house for 2 years, and now have been living in it for 2 weeks. Just built an off grid solar generator for some power, so now I sleep with a fan pulling in wonderful cool air through the windows. It's great!" http://www.tiny-house-living.com/my-darling-tiny-house-on-wheels.html
Add transmitter, will travel.
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