RE: shields attached at the source-feed-audio power end.... is radiation from the shield prevented?
Wouldn't the responses of those using such transmitters and/or the OEMs of same be the most suitable, given that such responses are based on honesty and scientific accuracy?
Rich, I can't take you seriously. You're dodging your own chain of discussion. I don't know what you are trying to achieve, but support of the part 15 hobby seems to have little to do with it.
Now you belong to them. I'll be on summer break.
Sayonara, Mr Blare.
I probably didn't explain myself clearly, so here goes.
I had a Talking Sign transmitter installed on the ceiling of a house I owned in Pitt Meadows. I drilled a hole in the house wall through which I threaded the wire antenna. I ran the antenna up a section of PVC pipe, and mounted that pipe on the outer part of my house, so that the wire antenna remained vertical.
The first install had the wire antenna below the roofline. Range was not all that great.
I then installed the PVC pipe higher (I also moved it closer to the house so that I could use that extra wire for height) so that the antenna went above the roofline, and range improved dramatically.
For the raised antenna, I achieved the greatest range by far in the direction where there were few obstructions - it was mainly open fields. I achieved the poorest range in the built-up directions, where there were many buildings.
I concluded from this evidence that the higher the antenna, the better, primarily due to fewer obstructions.
In both scenarios, the only thing that changed was the height of the wire antenna. The ground, the transmitter, etc. remained constant.
It is true that more of the wire antenna was vertical in the 2nd scenario, but I only had to raise the pipe a foot or so, so the change there wasn't dramatic.
It is possible that noise played a factor in the different ranges for different directions, but that cannot be said for the dramatic increase in range just by merely clearing the roofline for the antenna.
Going back to the original post, I believe that my experience at least casts some doubt that the only reason an elevated antenna may have better range is because something else is radiating, such as long audio lines, and taking the installation out of the Part 15 rules.
That helps me understand what you did.
Neil
The 2nd installation I've described is that I currently have a Talking Sign transmitter installed on the first floor of my townhouse (it is wood frame with vinyl exterior). The wire antenna is inside. There are many 3 story townhouses surrounding mine.
My signal barely gets outside that townhouse complex (maybe 600 feet at most). But I can hear it the farthest in the direction that is most free of buildings. I'm the 2nd to last townhouse, and there is a park past my neighbour - in that direction, the signal has the best range (about double).
So again, it appears, at least on the surface, that obstructions, or lack thereof, have something to do with the increased range.
If anyone has any better explanation, go for it.
"If the shield of the audio/power cable is grounded only at the supply/feed end and NOT at the transmitter end, will that shield tend to radiate?"
It will, if any of the conductors enclosed by the shield connects to the circuit ground bus of an elevated Part 15 AM transmitter, with no r-f filter or choke for those conductors at/in the transmitter.
The link below explains the reason for this.
http://www.w8ji.com/coaxial_line_and_shielded_wires.htm
When I look at Artisan's "Talking Sign" on the web it is a FM transmitter. So hight would be a factor. Then in the next few comments we are talking about AM transmitters. So are we talking AM or FM?
The Talking Sign (TS-100) is an AM transmitter, and is the precursor to the ProCaster (the company eventually became ChezRadio).
It looks similar to the Talking House, but has a smaller footprint. It also sounded much better than the early Talking Houses (I have no experience with the IAM ones). But the big reason I got a couple was that, unlike the Talking House, the Talking Sign is Industry Canada certified (RSS210).
That makes things a whole lot clearer to my brain.
MOST licensed AM stations place their antennas in open fields, often slightly higher than surrounding terrain, free of physical obstructions.
MOST licensed AM stations in this area are generally located in open areas that are slighly "lower" because there is a tendancy of the ground plane to be in a wetter environment.
WDAE:
WDCF: 
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