- Posts
I see nothing in the manual about adjusting to Part 15 limits for our purposes, nor is this us mentioned in the manual. It’s here, in case you want to look for something I missed:
http://radiosystems.com/legacytechsupport/Manuals/TR-6000Manual07-17.pdf
TIB
Wow! Looked at the manual and it sure is a complex array of controls. If it can operate at 100mW it’s like rocket science(well not quite) to do it and I couldn’t tell from the complex set up how to adjust power at all. Or how you know what it is. Guess you could also just use a wire directly to the antenna connection.
Best thing is to call Information Station Specialists.Tim mentioned: “But notice it says Part 15.221 and specifically states for carrier current or educational campus uses.”
There’s an interesting side story about that.. which may derail the thread a tad, but it’s still in the ball park of the subject on hand;
Recently I’ve been researching the use of part 15 in Drive-ins, and in the book ‘Drive-in Theaters: A History Since it’s Inception’ on page 141 it says: : “During the summer of 1989 the FCC put into effect a ban on low-power AM broadcasting for unlicensed applications.” — I had no clue what the book was talking about, but it said this rule change would force Drive-ins to cease broadcasting to car radios, as well as Disney Worlds brand new 3 mile part 15 AM broadcast which LPB had just finished installing..
Since I was reading this book on Googlebooks, the pages immediately following is omitted, so I was left not knowing what happened next. I never heard of any part15 AM “ban” in 1989 or any other time, so dug around looking for an answer.. and found it in the 1989 FCC GEN Docket 87-389 (aka:FCC 89-103).
At the time the FCC was trying to make part 15 rules more uniform, and enacted several rule changes, one change was to combine ‘carrier current’ and ‘leaky cable’ into a single rule. A group of petitioners which included LPB objected to the rule change because due to apparent technical reasons, it resulted in a severely decreased range of certain systems in the lower AM band (but didn’t effect the upper bands).
The confusion arose from misconceptions that ‘carrier-current’ and ‘leaky cable’ were one in the same, but they’re not. If I understand it correctly, though they both employ an induction method, leaky cable actually in essence acts more as a free-radiate system, whereas carrier current is more of a near-field radiation system, so different restrictions are applied. So in 1990 the FCC amended the rules again in FCC 90-404 to correct the situation:
“…The Commission did not intend to preclude existing Part 15 operations.. .. Accordingly, we are allowing carrier current systems operating in the AM band to comply with either the new limits or those which were contained in the former rules.. While this change will lessen the uniformity of Part 15 emissions standards, we believe the benefits of applying the former standards in this case outweigh the advantages of uniformity… we are granting the request to subject leaky cable systems operating in the AM broadcast band to the same field strength limits and equipment authorization requirements as carrier current systems.”
So that cleared up what was behind the story of the “LPAM Ban” described in the Drive-in history book, but I’m still a little confused about if 15.221 can be used by other entities other than educational institutions or not.
But getting back on track, one thing that does appear as obvious is that the average part 15 hobbyist can not legally use a ISS TR 6000 TIS transmitter to achieve “miles of range”, but it does appear with proper adjustments it could be legally used to achieve maybe a mile if your surroundings are optimum.
Some of these transmitters that say zero to so many watts isn’t gradual but by increments. It could go to zero but then go in jumps of 1 or two watts at a time to the max. Best bet to use this and be legal as per part 15 is to contact ISS and ask. Most importantly is the power continuously adjustable and how does a user know what the setting is or what the input to the final is.
With a transmitter like this it’s too tempting to go higher to get farther.I’m sure your right Mark, I haven’t looked at the manual Tim provided, but did note that even the ISS Products page specifies the TR6000 can be used for “unlicensed broadcast operations under FCC Part 15.221”
http://www.theradiosource.com/products/tr6000-1573.htm
Hmmm.. I guess 15.221 must therefore indeed be ONLY FOR educational institutions after all… I’m still a bit confused over the difference of leaky cable and carrier current.
Yes, that’s what I noted too that it can be used for part 15.221. And yes I saw it is continuously variable. But having something like this with all that power available with just the turn of an exterior control it’s too easy to just turn it up and very hard to stay way down to legal limits.
From what I have learned from all the time I have been on these forums leaky cable is a type of cable strung over an area that is specially made to radiate along the length, unlike shielded coax, while carrier current uses the power lines. Please correct me if I am wrong.
- You must be logged in to reply to this topic.
