The designer of the mathching curcuit designed it to match 3 meter antennas and nothing more. I have that on personal knowledge. Why not buy one and and DIY rather than use free softeware and share your real time experiences?
If this was a trial court hearing evidence we'd be doing a good job.
Should this situation ever have proceeded to a "trial?"
Isn't it the burden of the plaintiff to provide evidence to support their allegations beyond a reasonable doubt, before such is ever brought to trial (either formally, or informally via the Internet)?
Yes, Rich. especially on the 4th in the midst of our Independence.
Unfounded acusations are not free speech.
Let's talk about wires and sparks like we used to.
RE: Reply #107
The designer of the mathching curcuit designed it to match 3 meter antennas and nothing more. I have that on personal knowledge.
How is it, then, that the KENC transmitter reportedly was able to be matched into a ~ 3-meter antenna when "grounded" to the top of a 40-ft tower at KENC, when that feedpoint impedance would be much different than that of a ~ 3-meter whip, alone?
Why not buy one and and DIY rather than use free softeware and share your real time experiences?
I paid $400 for the NEC4 software I use.
Just to note that I have real-time, hands-on experience with AM/FM transmit/receive systems going back to the mid-1950s.
Modern software analysis of antenna systems confirms the information given in antenna engineering textbooks, and is accepted by the FCC to license AM broadcast stations.
Why not acquire, and learn how to use such software before judging its accuracy and/or usefulness?
Who here has the ability to edit post #104 and remove everything below the link with the exception of my first name at the bottom?
That text was put in there by accident.
Bruce.
Done.
Back in Post # 64 Rich said:
"The Potomac Industries FIM-71 was designed to measure VHF fields, and has a measuring range of 1 µV/m to 10 V/m. So it had no problem measuring a field compliant with §15.239, and less. But its manufacture has been discontinued.
"I think the FCC uses other instrumentation, anyway."
What, then, is the "other instrumentation" used by the FCC to measure field strengths per 15.239?
What, then, is the "other instrumentation" used by the FCC to measure field strengths per 15.239?
My earlier experience and present understanding is that the FCC has vehicles outfitted with calibrated receivers and receive antennas able to make and record field intensity measurements over a large part of the r-f spectrum to a known level of accuracy, and now including the GPS coordinates where those fields are measured.
So far I have not found a list of such instrumentation, which probably the FCC wouldn't make public, anyway.
If we want to accurately measure our FM Transmitter's field strength to be sure we're following the rules you'd think the FCC would make that sort of public otherwise its really like shooting in the dark and hope you hit the bulls eye.
At one time it was the "wrong-doer" who used secret methods to sneak by with hidden activity.
Now it's the other way around.
RE: Compliance with FCC §15.239, if such is desired...
Those not willing to research, purchase, and learn how to use the very expensive test equipment needed to make accurate field intensity measurements in the FM broadcast band might consider buying transmitters that are already (and provably) certified to meet FCC §15.239.
We talked about that too and if the inspector sees your over the field strength limit he will give you A citation. Best case scenario is purchase your favorite FM transmitter that says its certified. If you get an NOUO and you show them you are trying to obey the rules by purchasing a certified part 15 Transmitter they might not fine you. You can also offer them that you will turn down the power level if your Transmitter has that capability. That or let them know you will either purchase a different Transmitter and ask them what they recommend or have them test again after you calm down the output of the translator. There are attenuator pads if if necessary. I really think if you show in good faith that you are willing to cooperate you will get a better result then if you bad mouth the inspector and act like you know everything.
It took awhile to decide which thread to add this message to, so I picked this one because the subject is the still ongoing movement to seek an improved VLPFM signal strength for Part 15.
The main talks toward this effort are happening at the ALPB Meetings, but further commentary continues here on this site.
At the recent Meeting I went on record taking the position that upgrading 15.239 to match Canadiean BETS standard (1000uV/M @ 3M) would be a reasonable improvement which would probably have the support of certified transmitter makers.
In FM signal testing here on the campus of Worldround Radio we have demonstrated the marked improvement in local area coverage using the BETS setting on a Wholehouse 2.0.
But today I have decided to go on record with another position which comes to me after listening and thinking. I believe it would appear foolish if we made our pleading to the FCC based on the need to extend such formats as "album oriented rock" or "Spanish music" or nearly any other format. After all, the Part 15 rules contain no language about content. It's a purely technical document. Therefore any case made by petitioners to upgrade the FM allowance should be made on purely technical argument without reference to "serving a particular audience in any form." The FM BETS standard works for Canada and could just as well work for the Homeland.
Yes and if we stay on topic with interference, Harmonics, Spurs I think we'd be better off when we pleed our case. Don't forget to add that Canada has had the BETS standard and too many canadian transmitters find their way to the USA either through garage sales, Ebay, Amazon, or just going to the store and buying a transmitter and put it in your car and take it home and open the box and run it on an empty frequency. That said I think if we show that alone the FCC may give the go ahead to flip the switches on your transmitters to the BETS setting. We could have a USA BETS.