RE: .. How does such an install correspond to the objectives of this discussion?
If that isn't evident to you by now, then I have little interest in responding to you further about the topic.
What is evident to me is that until a few post ago you insisted it made no difference where the transmitter was located within a 3 meter antenna system, and now you say the opposite. Then you throw a spin in to distract from the discrepancy by indicating I am somehow actually the one missing the point.
Elevating a non grounded transmitter in no way relates to anything we've discussed here.
That's fine.. it appears evident to me that you simply changed the subject of the matter midstream because you somehow backed yourself into a corner.. I guess your solution is to pretend that you didn't.
To make a more complicated discussion simpler.....going back to the original question starting this thread...
Question:[me] If you have a 102 inch whip antenna and a 4 inch ground lead, would that perform equally to a 102" ground lead and a 4" antenna?
Answer: [Rich's response] In free space it doesn't matter to the performance of that system configuration as to which of the two output terminals of the transmitter connects to a 4" wire called "the antenna" and the other to a 102" wire called "ground," or with the wires reversed.
I get from that answer, that the answer to your question is yes.
As for the metal pole acting as a ground lead and violating rules you could contact the FCC and speak to someone technically knowledgeable or an agent and ask.
But even if the pole did in effect act like a longer ground lead it wouldn't make the performance any better as the tuning circuit with the coil in the rangemaster is made to work with a 3 meter antenna and longer won't work better....manufacturer will tell you this.
You can have the transmitter right side up, upside down, mounted anyway elevated and it will work the same.
It doesn't need to get more and more complicated and you getting more frustrated.
..I get from that answer, that the answer to your question is yes.
That's what I was getting as the answer too, until he began suggesting the loading coil might not be able to resonate the system, thus very poor performance and suggested an elevated dipole configuration. So his answer becomes "Yes, or maybe No".
Yes, the discussion frustrated me.
As for a part 15 transmitter being designed specifically to tune a 3 meter system, I guess that would be accurate, but it doesn't equate with being limited to it. There is no question that a longer antenna system for a part 15 transmitter will always result in higher performance.
Yes the longer antenna would give better performance IF....that is IF......there was no tuning circuit with the loading coil on board the transmitter and then you would have to have to get to at least 150ft length of antenna to have 1/4 wave of the top AM frequencies. But since that is not legal or practical the tuning circuitry on board especially with the loading coil on board like the Procaster, Rangemaster, SStran, Sean Cuthbert,etc. was designed to work with the 3 meter length and adding more antenna will not allow the tuning to get the best RF transfer to the antenna. You would have a mismatch. Maybe that's what Rich was saying when he mentioned the loading coil which is on board the transmitter.
On a smaller scale I am on FM in Canada and I use the Decade Ms-100 and the telescoping antenna attached is 35" and depending on the frequency I adjust the length for a 1/4 wave length but I don't go by a chart that says what length that should be I actually measure with a hand held frequency counter that also has a field strength indicator in the form of a bar graph and going by that I get the exact length by watching the meter as I lengthen and shorten the antenna to peak it for the most signal strength on the meter. The antenna is actually peaking the output as the transmitter has no coil and tuning on it's own.
Now you could do this with the AM transmitter too and you could by the antenna length get the most RF out of the antenna but like I said with AM frequencies that length is so long that it's not practical and then the legality comes into it so to get the most RF to radiate with the way to short antenna there's the loading coil and tuning cap on board the transmitter to make the inefficient antenna work best. Here's a pic of the loading coil.........
... the loading coil on board like the Procaster, Rangemaster, SStran, Sean Cuthbert,etc. was designed to work with the 3 meter length and adding more antenna will not allow the tuning to get the best RF transfer to the antenna. You would have a mismatch. Maybe that's what Rich was saying when he mentioned the loading coil which is on board the transmitter. ...
Typical radiating conductors of Part 15 AM antenna systems consist of a ~3-m whip (or wire) attached directly to the tx "antenna" connector, and all of the conductors connected to the circuit bus common, chassis, or r-f ground terminal of the transmitter.1
The internal loading coil included in some commercial Part 15 AM transmitters usually has customer-selectable "taps" to vary its inductance. This may enable a better match of the transmitter to the impedance of the complete antenna system connected to it.
Increasing the lengths of those radiating conductors decreases the inductance needed from the loading coil to achieve the best possible impedance match between the transmitter and the antenna system.
A stock, internal loading coil typically cannot match the tx to its load impedance if the radiating length of the antenna system is much less than 3 meters, because the relatively high inductance needed to do that is not available from that loading coil.
Using longer radiating lengths for the antenna system may enable finding a tap on a stock, internal loading coil where a reasonably good impedance match is possible.2
1. Including a path from the transmitter system to an a-c power utility ground rod buried in the earth.
2. The "KENC case" is one example of this, where reportedly a transmitter with a 3-m whip attached
and having an internal loading coil was installed and connected to the top of a radiating (yet "grounded")
metal tower about 40-50 feet tall. Apparentlythat transmit system was able to be optimized
for that configuration.
Hopefully this post will be understandable to everyone. Using (many) fewer words in it would not provide a sufficiently accurate description of this scenario.
What I saw happening in this thread is that Rich Fry was responding to questions regarding various configurations of antenna and loading coil with the constraint that the length be 3 meters. The position of the loading coil was changed and initially the effects of doing so were not considered.
Now the thread is focused on whether the loading coil will resonate with various lengths of radiators. What was stated but was perhaps not obvious in the early posts was that changing the lengths of the ground lead and antenna while maintaining a total length of 3 meters will change the required inductance of the loading coil. Moving the loading coil up the antenna requires more inductance which means more turns of wire which increases significantly the resistance and loss to RF. When this is considered, the radiated power decreases due to the increased loss and the expectation is reduced range.
Given this, the best placement for the loading coil is at the base of the radiating antenna (or inside the transmitter) where the inductance required is lowest for a 3 meter system.
Thanks Neil, that does help, but after re-reading R Fry turning post and graph details several times I was able to get a general idea of what he was saying.. I'm no engineer which is why I inquired about the alternate installation method to begin with, I don't know squat about inductance.. He could have at least said.. "Wait, there's something I didn't consider". Instead of just tossing that bit of info in as a side note after conclusions that a long lead with short antenna (3 meter) would perform even better.
His answers was yes, yes, yes, it will work, and the moment I found satisfaction in that, he casually says No it won't really work.
I understand, R Fry forgot to consider inductance, and I'm probably making too much out of it. The actual answer to the feasibly of the configuration I proposed is that it probably will not work. Right?
As I understand your various configurations proposed, they will all work, but the question may then be asked "which is optimal?" Usually optimal means to us, which gives the greatest range but it may also include considerations of environment, security, regulations, all of which are likely apparent to you since you mentioned some of these.
When someone posts questions it is not required that they be an engineer or ham operator, etc. rather I think all of us want to try to help as we can. To do so often requires stating technical things in a manner which is useful and which may omit confounding variables in order to get to the point. To do so often requires not stating the subtle "gotchas" that engineers might know but are not necessary for successful application of the technology.
A disease of old professors is that they try to be philosophers, so here's my attempt. To use and improve technology does not require intense education to succeed, but rather a willingness to question and invest some effort in learning some basics. You have done so in this thread and I hope, despite your frustration, you will continue. If something is not clear then ask again. As a former teacher I can tell you and all reading this that people learn differently. In class I tried to present the subjects in three different manners hoping that at least one of them would connect. This required patience on my part and also patience on the part of the learner.
That's just the thing Neil, I did specifically ask if it would of be optimal performance to have the xmtr at the top rather than the bottom of the 3 meters - several times, and several times the answer was yes, it would most probably exceed the performance of having the transmitter on the ground. I see no reasoning in intentionally "omitting" crucial information that actually proved all his prior responses concerning the matter were false. No, I think he just forgot to factor it in, and once he realized it attempted to save face by nonchalantly tossing it in then suggesting an elevated dipole instead, and then made me out to be the one who was at fault and didn't understand.
I understand what your trying to say Neil, but my questions were clear, and his answers were clear.. but those answers were flawed.
Yes the longer antenna would give better performance IF....that is IF......there was no tuning circuit with the loading coil on board the transmitter and then you would have to have to get to at least 150ft length of antenna to have 1/4 wave of the top AM frequencies. But since that is not legal or practical the tuning circuitry on board especially with the loading coil on board like the Procaster, ...
Mark: As your concern probably centers on the Procaster, I Googled it to see what I could learn about how it handles "antenna tuning."
What I found may or may not be up-to-date information, but if it is valid, then the Procaster appears to have a fixed, internal loading coil with no taps along its length, and where the adjustment for the best match to the antenna system is done with a variable capacitor.
That configuration would permit optimizing the match to the antenna system with no modifications to its internal components — only an operator adjustment of the included tuning capacitor.
The on-line installation sketches and text show the system mounted on a building top. and requiring the connection of a long conductor from the transmitter to a buried ground rod.
Of course that added length of conductor becomes a radiating part of the antenna system, which then has less capacitive reactance than a ~3-meter radiator by itself.
It also has greater radiation resistance, which results in the longer/taller antenna system radiating more of the available r-f output power from the transmitter than it could using the 3-m "antenna," alone.
And it shows that an unmodified Procaster must be capable of tuning/matching into an antenna system having a radiating length exceeding 3 meters.
All the information you could want about the protester is readily available at their website: www.chezradio.com including the full installation and operation manual
The drawings of elevated systems with a ground lead going to the ground below have been gone for a few years now on their site and in manuals. They DO explain that a long ground lead is trouble, and explain that the transmitting antenna supplied allows enough "spare room" to have up to a 14" ground lead and be within the rules.
My Procaster has been in service around the clock for over 5 years with no loss of power output/range or instability of frequency. I check mine with a spectrum analyzer for frequency, and an actual calibrated Potomac Field Intensity Meter for field strength at about a dozen points I've designated, every few months just to see how it's doing. Rock solid.