My point was that I don't think that the FM-100B can be used in any sort of legal fashion - it's just too powerful. There are huge differences between marketing language and reality.
A Ramsey 10 c that did the same thing, drifted until it warmed up. After it settled down it covered nearly 1/4 mile mounted under a ground plane antenna built for the 10c. It wasn't too bad but as i has already been pointed out, it would not be reliable for 24/7 use or serious part 15.
I have a North Country Radio (I think that's the name)
MPX-96. I have five 6 dB attenuators on the output,
and we put it on a spectrum analyzer and it's clean.
I think the output at the transmitter jack is 50 mW,
but the 30 dB of attenuation and lousy antenna make
it go only a couple of hundred feet.
I cannot go above the limits specified in 15.239.
It's just not in my nature. Although I know a
few more hundred feet probably wouldn't matter,
I am not capable of doing it and being relaxed.
That's just me.
Bruce, Dog Radio Studio 2
It is interesting isn't it regarding the range of the Ramsey vs say a C-Crane or Decade...not to mention the avg TPO on them.
On the 100 model, which is what I use, its peak output once the two filters are tuned properly is roughly 28mW. If the last filter is bypassed, which really does nothing in the way of filtering when in place, the output will jump to around 62mW. Obviously the 2nd filter serves more as an attenuator, though the circuit is indeed a filter. The majority of filtering takes place at the bandpass torroid coil and two 4 turn coils prior to it and both before the final output transistor.
Combined with both filters and the use of the internal whip, the field strength @ 3m comes in at around 360uV..plus or minus a few points depending on nearby objects absorbing the signal. These are not accurate, just ball park measurements using a quick and dirty altered 75-300 ohm adapter with the coil removed so the two "rabbit ear" whips are actually connected to the center conductor and ground of the analyzer connector.
From what I gather, the 100B model has a bit more output with the use of the FET element instead of a transistor. Much of the circuitry on the 100B is surface mount, whereas the 100 has the traditional feed through components and IC's in sockets. The 100B has foil trace coils where the 100 has traditional wound coils.
However that 100B is also subject to the slightest static buildup and is prone to blow the output FET. My 100 model has been running 24/7/365 since the day I purchased it as a kit and its all pure stock with the exception of the PLL lock path using a different resistor to improve the bass response a bit in the audio...no other mods have ever been done to this unit.
I believe that if these were "too much little box"...right out of the box...that after 15 plus years and one model above the original, along with the 25 and 30 models, that the FCC and Ramsey would have done something by now to tone them down considerably.
Neither the FCC nor Ramsey has changed anything regarding these kits.
I attached my 100 model to an external 1/4 ground plane antenna through 25 feet of RG-59U coax with the antenna sitting on a fence pole about 10 feet in the air and the range is roughly a 2 block radius clean stereo. By the time I reached 3 blocks, the reception lost the stereo but the mono signal was still quite clear. At 4 blocks the mono signal began to fade in and out and at 5 blocks it dropped off sharply. With the internal whip, the range is about half, which is plenty IMO...but also not such a huge amount that would present problems in as far as the range they can cover.
The outdoor antenna is mounted so that there is nothing in the line of sight from it and going up the street 5 blocks to test the signal. Perhaps with another 10 feet of height on the antenna the range might improve a bit.
I saw a Ramsey unit being used in a photograph recently right here on this forum..I believe it was a radio swap meet or something featuring our SSTran maker holding a mic speaking into it while demonstrating the AMT5000...I could be wrong but that box sitting on top of the CD multi-changer sure looked like a Ramsey 100 or 100B box to me.
Point with that is are those Ramsey 100 and 100B models, or any other model with 25mW or so, that much of a concern when blatant pirate operations using several watts or far more give anyone concern in having a Ramsey or using one?
And there are thousands of them in use all over the country by now I would imagine.
It can be a bit scary eh. But as I have pointed out, as have many others across different forums including Ramsey's own forum...if these things were that much of a problem, the FCC would have required Ramsey to do something about them a very long time ago. This also applies to their AM-25 unit and the "can operate at 1 watt" debate.
Out of them all...every single manual that comes with them do point out that it is up to the end user to operate them properly and use the supplied parts and antenna. Ramsey also has the operating information posted on their website and forum.
I prefer to use the Ramsey unit simply because it is in a metal cabinet, well grounded and shielded, uses a grounded AC plug unlike others that run via a wal wart adapter, and all the IC's are field replaceable as they all sit in sockets...though I have yet to replace a single IC or other component due to failure. I have a Panaxis FM-10 transmitter fully equipped with the stereo generator, PLL exciter, 10 watt power amp and power supply all within the original rack mount cabinet. It sits in the "X" closet and has been there since the day I completed the Ramsey 100 assembly and began using the Ramsey.
I suppose its all a matter of personal preference using them or not. I truly believe that using any of those Ramsey units within their designed parameters that no one has anything to worry about..again since it has been 15 years these things have been on the market and continue to be marketed, that they are not of any major concern to the FCC with their 25mW of power.
An interesting point regarding the legality. An example is the Rangemaster and its power adjustment capability. Most declare that this is to compensate for antenna system loses. Well that is all well and good, and no big deal really. However in as far as legality to the letter of the law...well we all know the numbers don't we. And no where in those rules does it say anything about a Part 15 certified unit being able to have the ability to power adjust to compensate for the set length limit of a 3 meter antenna system....yet that transmitter can have its power adjusted considerably, and even if it is to compensate for antenna system losses, that power adjustment anywhere above the 100mW limit takes the unit itself outside of that set limit, therefore it is no longer at the 100mW input power limit, but more and sometimes a lot more.
So what is the legality of that situation??? Just because the FCC went ahead and stamped a certification number on it...even when the test unit also had the power adjustment capability and known to the FCC...did the FCC stamp that certification number on it WITH having the unit tested at its full adjustment range for power???
I doubt it.
The Procaster...its power is pre-set to run between 95 and 105 mW, which self adjusts but does not go anywhere beyond 105 or so mW. A far cry from some who have measured the Rangemaster's TPO of 400mW idle.
Which one is more "legal" or gives an operator more comfort in being in compliance???
Point here is that there are units with no certification number, put out a bit too much power and range yet continue to be manufactured and sold in the US, while others carry certification numbers and can be adjusted way beyond the legal limits.
So to be saying one is compliant when operating a unit that can be adjusted 300 percent above the legal limit regardless if its to compensate for losses or not, and one that operates with no power adjustment at 25mW and be so worried about compliance because there is no FCC number on it, yet continues to be marketed and sold...well one has to wonder if all of this is just bandy back and forth debate material for late night round table forum discussions instead of any real legal issue.
Its all interesting anyway. Whatever works for each individual. Live and let live is my motto.
RFB
With more and more imported, straight-up outlaw stuff coming on the market, will the Commission go UK-style and simply forbid any kind of intentional radiation?
On the one hand it's been great getting connected to the global market place - over the past couple of years I ordered USB large diaphragm mics from Germany, an inexpensive fixed-values audio compressor circuit board from Italy, a couple of relay control boards from the UK - great fun.
On the other hand I wonder how we can maintain an experimental presence in the receiver-rich spectrum locations like the analog AM and FM bands when anyone with a paypal account can have a plug and play 30 watt stereo FM transmitter delivered to their door for next to nothing.
From the attack on in-car FM modulators (where a Ramsey FM kit was thrown into the mix as a shot across the bow, I imagine) to the HDRadio/IBOC issues to the "FM chips in all cellphones" attempted mandate to the new round of state laws in place or proposed to penalize unauthorized broadcasters, the death throes of the NAB are looking like they are going to get very ugly.
I like your comments very much, SCWIS, and believe the underlying concern about the future of legal low power is something we should always view with a parental concern, since it could be taken away as you infer, but not only as a backlash against over-power transmitters.
There is also the expanding clamp-down on liberty by the security state which could indict low power radio as a "security threat," as they have toothpaste tubes and shoes.
Our thinking is being done more and more on our behalf, not by thinkers, but by professional non-thinkers. There are a lot of oxy-morons in charge.
I wouldn't dare use a Ramsey FM100 or 100B or anything that wasn't certified and was that powerful, unless I was attempting to operate under the radar of everyone and/or just plain experimenting. If you're getting out into the community and advertising your presence (i.e., have some listeners), then it's suicide not to be Part 15 compliant. It's only a matter of time before someone complains, or you get noticed by that FCC/Industry Canada inspector.
In another thread, there was a question of what was a pirate. Well, if you're not Part 15 compliant, whether you're trying to be or not, then you can be deemed a pirate, period. What's the point - it's better to be legal (even with reduced range) and not have to worry about it. I know I'm in this for the radio programming and the listeners (secondarily, the technical aspects), not to one up the law, regardless of how stupid one might feel that law is.
ArtisanRadio is very reasonable and wise to stick closely to the rules.
The fears expressed in earlier posts do not find the present Part 15 rules "stupid," but the fears are concerned that, as SCWIS said, the U.S. could possibly do what England does and outright ban unlicensed broadcasting because of so many over-powered transmitters being imported. If that happened, sticking close to the rules would mean no broadcasting at all.
My comment which followed is, again said in fear, that the security arm of the government could conceivably declare unlicensed broadcasting a reason to be put on a "watch list."
But there is a reason I used the word "fear" so many times. It explains why we are afraid to disobey the Part 15 rules and why we hope the rules aren't taken away.
We have agreement in fear.
Recently RFBurns said we should enjoy the privilege we have with the Part 15 rules and he advised that we stick very closely to those rules so that we protect our reputation as a responsible bunch of broadcasters.
As a matter of fact, this website, Part15.us, has always been very sharply devoted to Part 15 and has consistently discouraged any leaning toward "exceeding the speed limit," as it were. In other words, this is NOT a pirate website.
The talk that goes on here mostly tends toward knowing the rules, understanding them, and trying to clear up any confusions that come to our attention.
At times the subject becomes very complicated and that will always happen because the engineering principles are not simple.
If this was on C-SPAN I would hand the conversation over to a colleague.
Thank you Carl.....Indeed following the rules is important. It is up to each individual to...as the old saying goes..."play by the rules".
Ok...so some may not know these exact rules. Easily found via a simple web search. Ok great! Now lets examine the rule about Part 15 for the frequencies within the FM broadcast band.
15.239 is the section specific to the FM broadcast frequencies.
It says our field strength cannot exceed 250uV/m @ 3m from the radiating element................
.............................................then it goes on to another sub part for the next set of frequencies above the FM broadcast band.
Hmmm...did I miss something? OR did they leave out the part about "Thall shall not exceed xxxuW power"??
Hmm....looking..............looking...........looking.........nope...nothing about a power output rule for 15.239 in the frequency range of 88-108Mhz.
Ok great! So what does that actually mean anyways???
Well for starters...it means...and can easily be decoded by reading simple english...that the field strength of the signal coming off the antenna....which is NOT specified as to what type of antenna, how long of an antenna, how big of an antenna, how tall of an antenna, how short of an antenna, how small, how high, or how low this antenna must be...it only says 250uV/m @ 3m from THE ANTENNA.
There is not even any mention about limited lengths of a lead, ground lead, coax, feedline or any other wire or conductor. Only 250uV/m @ 3m from the antenna.
Well co-host...that sure does leave things rather wide open ended regarding exactly what it means in terms of "power output" from our transmitting device now doesn't it!
Ok well let's see here.....wow a very wide variety of transmitting devices to sift through. Some appear to have a certification number on them...these seem to be factory built...put together at some sweat shop assembly line overseas. These others over in this pile to the right seem to be in tons of bits and pieces each. Hmm...Ok these appear to be KITS and require assembly.
Ahh lookie here!!! There is specifics within the Part 15 rules regarding kits and pre-built devices. Mostly the rules focus on devices that are intended for market and public sale, that they be certified to be in compliance.
All well there...ahh here it is....although this next part really does not address KITS, but does address home built devices and that they should not cause interference and that you can build up to 5 devices for your own use, and that good engineering practices should be adhered to. Hmm...would this also apply to kits purchased from a kit manufacturer since home brew stuff normally is built from individual parts and pieces much like how the kits are when they arrive at your door?
GREAT!!! I am still rather puzzled with this issue over "too much power" from a marketed kit by a US company selling these kits for well over 15 years and people's skittish feelings towards them and no mention in the FCC rules about kits only being able to output so so much power, with the exception of the 15.209 and a few others that DO specify the ABSOLUTE LEGAL power limit...where in 15.239....there is NONE!!
I am going to go out on a limb here Jim and take a wild goose guess that the FCC is quite well aware of what kind of TPO these devices marketed pre-built and in kit form can do. One such kit has been around longer than some of the certified units...and continues to be marketed in the US under the same manufacture brand...just a newer version of it.
Now kids....lets take a look at something related to this topic. Please refer to your FCC Part 15 handbook...thats OET Publication 63 for those who are not sure....and turn to page 2 after the preface pages and focus on 15.203.
The second paragraph...is of particular interest especially for one particular unit mentioned earlier regarding power output. In the 2nd paragraph noted with 15.203 it reads...
"..each Part 15 transmitter must be designed to ensure that no type of antenna can be used with it other than the one used to demonstrate compliance with the technical standards. This means that Part 15 transmitters must have permanently attached antennas, or detachable antennas with unique connectors."
Ok wonderful!!! Hmm.....is anyone connecting the fine dots here with this one and a well known..very popular unit that is certified, uses a common CB whip and certified to use that CB whip for the antenna that is mounted in a simple..but VERY common connection stub found on many bumper and rail mount CB antenna mounts...and the unit's power can be adjusted WAY WAY beyond the legal limit....and the FCC knows this as for every unit that is tested for compliance must also be accompanied by a full disclosure literature of the unit under test, including schematics, theory of operations, specifications, physical dimension specifications, and even good ol fashioned pictures.
Well Carl...as we get closer to the end of the show here..it seems that the rules have a few "loose ends" within them. For I see a number of CONTRADICTIONS that literally could be interpreted in a court case in any direction and would either help or ruin a defense with a violation.
Is there a violation to the use of a kit marketed in the US clearly known by the FCC and continues to be marketed for over 15 years and not any sign of a "HALT" or "STOP RIGHT THERE" from the authority to the manufacturer to correct these things on their products before selling any further units by either of the makers???
Tune in the next time for episode XXXX as we further dive into the black hole abyss of confusion...sometimes referred to as "The Holy Grail of the EM Spectrum" rule book and attempt to make some sense out of senseless mumbo jumbo cluttered clustered wording that means anything in a court of law.
Good night!
RFB