I have a question regarding the legality of transmitting through a REMOTELY located antenna/antenna tuning unit (similar to the ATU produced by Talking House).
I have had occasion to use one of the TH ATU's & have found it to be an impressive performing unit. I recall that ISS (Information Station Specialists) sold the complete kit which included a T.H. 5.0 transmitter, a length of coax & the T.H. ATU mounted in a kind of supplementary weatherproof enclosure.
Considering the FCC's rule stating that a Part 15 MW antenna must be three meters in length or less (including feedline & ground wire), it would seem that (on the face of it) this configuration would be a clear violation of the applicable rules, though I recall the folks at ISS claiming that, because the coaxial feed itself does not radiate, that such a setup would be legal.
Out of curiosity, I went back and checked the ISS website (theradiosource.com) only to find that they no longer sell the system in question. Would anyone know if this is perhaps because of some sort of definitive ruling as to the legality (or lack thereof) of the remotely mounted ATU system? I'd really like to know considering that I myself have been running one of these from my property for several years & would I'd hate to run afoul of the FCC!
Pat
I'm back to (sort of) answer my own question & to correct a misstatement. I got to looking around the ISS website a bit closer & I came across this...
http://www.theradiosource.com/products-infospot.htm
... that link takes you to the license-free system which utilizes the all-too-familiar Talking House ATU (I can't tell from the picture which transmitter is included here, though from the description I can fairly assume that it's the TH5.0)
I guess I can breathe a bit easier with regards to my own activities on 1690KHz!
We have discussed this topic many times here and the conclusion is that the Talking House and the supplied ATU were certified together by the FCC. It appears to be a legal system.
But you wrote "...a REMOTELY located antenna/antenna tuning unit (similar to the ATU produced by Talking House)". If the remote ATU is not produced by Talking House then the certification would not apply.
"If the remote ATU is not produced by Talking House then the certification would not apply."
Certification is not the defining "bottom line" of being in compliance.
The combined transmitter and antenna tuning unit of the Talking House V5 and external antenna tuning unit carries it's own certification to be used together, though the transmitter can be used by itself. Even the ATU can be used by itself, in a certain configuration.
For example, the OP could mount a transmitter directly beneath the ATU unit and use a very short connecting conductor from the transmitter to the ATU, keeping the whole works within the 15.219 3 meter limit rule, and it would be perfectly LEGAL.
Or, the OP could use a coax and connect a different transmitter and operate under 15.209, again being perfectly LEGAL.
In the other direction, ie the Talking House transmitter has a common off the shelf "F" connector. The transmitter could be connected to another style external antenna unit via a short connecting conductor and operate under 15.219 keeping the 3 meter limit observed..again being perfectly LEGAL. Or operate with a coax to a different external ATU and operate under 15.209 and again..be LEGAL.
If the transmitter with its common F connector were meant to only operate with the external ATU carrying the same certification number, the transmitter AND ATU would incorporate a very different, specialized connector on both the transmitter and the ATU, and the coax would have it's own specialized connector which would only fit to the specialized connector on the transmitter and antenna tuning unit!
Part 15 rules specifically state that any unlicensed intentional radiating device sold in the US and certified MUST have a special connector for the antenna, or have a permanent attached antenna. This rule applies to ALL intentional radiator devices that are certified.
It is apparent that the Talking House unit and it's ATU unit can be operated in various configurations under two specific Part 15 rule sub parts...ie 219 (as a combined pair), or 209 (operating separately from one another).
As to the ground shield of the coax connecting the TH transmitter and ATU together radiates or not..has not been tested outside of the OET testing and documentation and since that documentation has been removed off the OET database, well it remains to be proven that the coax does not radiate. Someone with this setup should conduct a test and see if that coax radiates or not and report their findings.
Until the FCC issues a notice regarding the Talking House and it's external ATU operating with a length of coax is no longer legal to use, it is perfectly legal to use as is (combined TH unit and it's external ATU). But as noted already, they both can be used in a different configuration under both 15.219 and 15.209, but setup configuration MUST be observed so that either one of those sub parts of the rules are met.
The other concern to which the OET documentation would prove, is how that ATU was mounted when certified. The operations manual are not the rules, however at this time is the only viable, though not bottom line legality of use, means of operating the units legally. Again until otherwise specified by the FCC, it's best to use good judgement in configuring this system per at least the certification device intent..which is "Real Estate Transmitter", which taking that into account, a typical real estate for sale sign is approximately 1 meter or so in height, and it is a very good bet that the unit was certified to be set up 1 meter off the ground, the coax ran along the yard into the house, and the transmitter inside.
RFB
Buried deep in the dusty basement of the FCC Headquarters is a file stating that (i am paraphrasing) any unit (part 15 device) could pass certification as a whole system. Or something like that. Unless this has changed and i am not aware of it then it should still hold true today. Yep, i just dug up the dead horse to beat it once again. If the unit passes certification as two parts in this case the talking house transmitter and the atu then all should fine in the part 15 universe. The transmitter is without a tuner if used in the setting labeled Antenna Select / Outdoor...this bypasses the circuit that is vital for creating the desired frequency in this case the tuner which is outside in your yard or on a pole etc. The ATU actually decides whether you transmit on 1610 or 530 khz.. The transmitter might put out a small signal but it won't go anywhere if the antenna is not tuned. I hope some of this makes sense. If not then i plead temporary insanity, after all who in their right mind digs up a dead horse to beat it again?? lol
The certification of the TH/ATU combination, with length of coax, redefines the definition of 15.219.
The main revelation is a re-definition of "final radio frequency stage".
Let's count the RF stages.
The final RF amplifier, which previously was presumed by most of us to represent the "final RF stage", is merely "a passing stage".
The next RF stage is the ATU, known in other part 15 systems as a "loading coil", but it also is not the final RF stage, therefore the length of coax used at its input does not contradict "total length of the transmission line rule", because the actual transmission line is found at the OUTPUT of the ATU/loading coil, and it is this point where 100mW cannot be exceeded and any added length to antenna, transmission line or ground lead must fall within 3-meters.
The final RF stage is the antenna itself.
Is this going to turn into another debate that goes round and round? I certainly hope not.
I'm not so sure that the TH and ATU certification redefines 15.219 and has a different definition for other devices also certified under 15.219.
Example..the Rangemaster and Procaster. Those are certified under 15.219. Yet they do not have a coax or external ATU fed by that coax. Both have it's tuning circuitry built in and antenna attached to the side or the top.
In the current information..ie the certification certificate which is available, does not specify a "special provision" notation, which if the TH and external ATU were to be considered special to 15.219, that certificate would indicate that.
Perhaps there is more to this whole thing and reason why OET documentation is missing off the OET database..who knows.
The other confusing double faced definition is the specific rule of certified intentional radiators MUST have a special non-common antenna connector, or permanently attached antenna, to which both the TH transmitter and it's external ATU use a common off the shelf F connector. The rule for a specific non-common connector came about in the rule changes in 1989. The TH V5 and that ATU were not around in 1989, thus is subject to that specific rule..but obviously is allowed to have that common F connector on the transmitter and ATU.
But like I pointed out earlier, until an official notice from the FCC and OET are published that the current TH and external ATU are no longer legal to use, it will be legal to use.
RFB
the actual transmission line is found at the OUTPUT of the ATU/loading coil
The writer of the above quote, and its readers should be interested in the location of the coax cable shown in the instructions for the TH/iAM external ATU (page 6 of link below).
http://www.talkinghouse.com/pdfs/OutdoorAntennaInstructions.pdf
Rich, I like the part at the very end where it says "and most usually, the ground wire length must be considered..." LOL
I wasn't aware that the ATU actually has a ground lug on it. Also, they mention that you should mount the unit high above the roof to get better coverage!