What does the FCC really mean?

[k7pp]

Perhaps this has been addressed before.

Every once and awhile,  I scan through Part 97 just to stay up with things.   I took one of the Extra Class exams on line and fell flat on my face when it came to the rules and regs.
Gee,  perhaps there have been a few changes in the last 60 years I wasn't aware of.....Hi.

Anyway,   Current rules tell me that the maximum transmitter output to the antenna should be no more than 1.5KW.

My question is,  where? 
At the end of the connector on the box?   At the antenna switch?  At the lightning arrestor?
What if I have 1.5 KW out and 100 watts at the end of my transmission line? (I know,  replace the transmission line)  What I'm getting at is that I don't see it stipulated anywhere in the rules.
Suppose I want to run 1.5 KW and I opt to use 7/8's low loss on 160 meters where I can get almost no attenuation at the end of the run, verses RG 8AU or some other line that has more loss?
Can I consider the output of the transmission line my transmitter output or is it the output from the box that generates the signal?   If that is the case,  is there another part in the rules that addresses this issue and stipulates the box??  I didn't see it if there is.
Suppose I have the power amp mounted to a pole so there is no line loss at all?   
Suppose I measure and adjust my transmitter so that I have 1.5 KW presented to the feed point on the antenna?   Will that meet the spirit of the rules?

Opinions?

73s
Pete

[n1uvi]

part 97 simply states

 No station may transmit with a
transmitter power exceeding 1.5 kW
PEP.


I assume that the 1.5 KW PEP means the average power of a single
RF cycle at the peak of a modulation envelope, at the output of the rig
minus any line losses

I might be wrong

[WA2OLZ]

How, then, does the FCC define "Transmitter Power" as used in 97.313? Part 97.3 provides definitions but there is no definition of "Transmitter Power" in 97.3.

I do not find any specifications in Part 97 that specify where or how power is to be measured.

Therefore, I would choose to measure output power at the endpoint of the transmitter - amplifier - tuner - feedline - matching device, the final connection at the antenna itself. My transmitter could then be loaded for whatever power is needed to provide the full 1.5KW PEP at the antenna.

So much for my armchair lawyer analysis of Part 97.

[M1ECY]

I think I would take the common sense approach to this.

1.5Kw at the antenna feedpoint makes the most sense to me (it is also where we Brits have to take the power maximum from, but we are only talking 26dbw PEP at the feedpoint)

I can't see how the playing field could be levelled any other way - as the original poster points out, feeder losses are a variable factor.

It is quite odd that there is no mention of where the power is to be measured, but as with our license conditions, there are probably a number of grey areas.

Cheers
Sean

[kb3ouk]

I think they mean at the output of the transmitter, before going through any antenna tuners, feedlines, etc. But that makes me wonder, if I built two transmitters, both which run the legal limit, then build a combiner and feed a single antenna from the output of the combiner, which is being fed by both transmitters on the same frequency at the same time, would that be legal? I say yes, because I have not found anything in part 97 that says you cannot run two transmitters at the same time on the same frequency, and if the FCC is defining the power limit by the power output at the transmitter, then the power level at the output of the combiner doesn't matter, as long as the power at the output of the transmitters is not over the legal limit. If you could make the transmitters and the combiner work, you could almost have an unlimited power output, I think a combiner that has 4 inputs would be nice, build 4 375 watt class D/E transmitters, feed the combiner with them, and you are legally running 1500 watts of carrier. The only thing I could see wrong would be if the FCC would consider the oscillator, modulator, and power supply as part of the transmitter, if they didn't then you could get away with a single oscillator, power supply, and modulator feeding the multiple RF amplifiers, but if they would then you would have to have an oscillator/power supply/modulator for each RF amp, and have to worry about getting everything synchronized. The other idea that I've often thought about playing with is two synchronized transmitters feeding seperate antennas, that idea would be the easiest to try out, and would still have pretty much the same effect, as long as the receiving station wasn't in a location where the signal from the two transmitting antennas were 180 degrees out of phase.

[k7pp]

Why don't I cut to the chase and be truthful!

I have a Collins 20 V and would like to run as much power as legally acceptable under the rules.
Since this beast can put 4KW PEP into a transmission line,  I want to radiate as much as legally possible.
I have a transmission line with 3db loss.   I plan on presenting 1.5KW PEP to the Balun.
So,  if I start with 780watts X 1.414 X2 +780/2, I should end up with 1492.92 PEP at my Balun. I plan on making an actual measurement with a through line wattmeter and keeping it in my records just in case the impossible happens.    
Would I be in compliance of the rules using this scenario?

73's
Pete

[w1vtp]

This is a completely editorial comment guys but this subject has been covered in great detail on this forum.  Maybe one of the moderators can make suggestions on where the references are.  I'm lousy at doing searches.

Please don't go down the trail of transmission line losses and antenna gain.  The power is measured at the transmitter. Period.

Transmission losses etc are used when calculating MPE (Maximum Permitted [RF] Exposure) which is a environmental health and safety issue.

Help moderators! 

Al

[K1JJ]

If an FCC inspector stopped by to measure power output, he would most likely want to stick his 50 ohm Bird wattmeter on the output of an SO-239  jack on the transmitter.  I doubt we could convince him to climb up the tower and take a measurement up there.  If the system used all high impedance open wire feeders off a balanced tank, he would probably pass.  (Maybe multiply E X I like the old days, but certainly not open the transmitter cabinet to verify)

Feedlines and antennas: I don't think they are concerned if someone is running a monster antenna that has +13dB gain over a dipole - or a mobile whip that has a -13dB loss over a dipole - or has a feedline with a -13 dB loss.   It's all about conveniently measuring the amplifier's power output directly at the SO-239 connector to comply with their admittedly hard-to-interpret law.

Based on Riley's inspections years ago, he was more concerned about behavior complaints received about a  ham - or that this guy was building an amplifier on the bench with TWO 8877s rather than actually axing the guy to load up his working amplifier. It was more like, "What are this guy's intentions?"

Things have certainly changed since the 50's and I think they have become more concerned with complaints based on offensive behaviour, QRMing, etc.  It is much easier to get into trouble with 100 watts acting like an a-hole rather than  being a FB OP running 3KW....

T


 

[WA2OLZ]

if I start with 780watts X 1.414 X2 +780/2, I should end up with 1492.92 PEP at my Balun.

(780*1.414*2) = 2205.4  I admit it's been a number of decades since I studied this stuff but I don't know where the +780/2 comes from.


By the way, 4KW is considered QRP by some of those guys that 'own' 20 meters!

[k7pp]

These are all valuable comments and I appreciate them all.  

I even agree for the most part.

Please direct me to a place in the rules where it says that transmitter power is measured on the output of the box.  The closest I can come is output of the transmitter.  
This will help me if I'm ever inspected as I could quote the rules.

If this scenario is true,  I could but a box on the tower with no transmission line and go from the box to the balun with the full 1.5 kw.  I agree this is a very gray area.
I agree that there are people that are running 10KW transmitters with 40000 ERP to the antenna and put out a nice clean signal.   They just don't talk about it.

I'm not one of them.
I just want to be ready for an inspection after the FCC cleans up 3840.  LOL.

BTW,  I based my calculations on 1.414 times the carrier for lower side band plus 1.414 times carrier for upper sideband plus carrier and then, divided by two which would account for the 3db transmission line loss.
Did I screw up?

[WU2D]

Typically with the FCC rules, the hows are listed separately in other sections. For instance for Part 90 which deals with intentional radiators like two-way radios, and for Part 97, the methods are all in Part 2 and you are expected to go there and cite those.

§2.1046   Measurements required: RF power output.
(a) For transmitters other than single sideband, independent sideband and controlled carrier radiotelephone, power output shall be measured at the RF output terminals when the transmitter is adjusted in accordance with the tune-up procedure to give the values of current and voltage on the circuit elements specified in §2.1033(c)(. The electrical characteristics of the radio frequency load attached to the output terminals when this test is made shall be stated.

(b) For single sideband, independent sideband, and single channel, controlled carrier radiotelephone transmitters the procedure specified in paragraph (a) of this section shall be employed and, in addition, the transmitter shall be modulated during the test as follows. In all tests, the input level of the modulating signal shall be such as to develop rated peak envelope power or carrier power, as appropriate, for the transmitter.

(1) Single sideband transmitters in the A3A or A3J emission modes—by two tones at frequencies of 400 Hz and 1800 Hz (for 3.0 kHz authorized bandwidth), or 500 Hz and 2100 Hz (3.5 kHz authorized bandwidth), or 500 Hz and 2400 Hz (for 4.0 kHz authorized bandwidth), applied simultaneously, the input levels of the tones so adjusted that the two principal frequency components of the radio frequency signal produced are equal in magnitude.

(2) Single sideband transmitters in the A3H emission mode—by one tone at a frequency of 1500 Hz (for 3.0 kHz authorized bandwidth), or 1700 Hz (for 3.5 kHz authorized bandwidth), or 1900 Hz (for 4.0 kHz authorized bandwidth), the level of which is adjusted to produce a radio frequency signal component equal in magnitude to the magnitude of the carrier in this mode.

(3) As an alternative to paragraphs (b) (1) and (2) of this section other tones besides those specified may be used as modulating frequencies, upon a sufficient showing of need. However, any tones so chosen must not be harmonically related, the third and fifth order intermodulation products which occur must fall within the −25 dB step of the emission bandwidth limitation curve, the seventh and ninth order intermodulation product must fall within the 35 dB step of the referenced curve and the eleventh and all higher order products must fall beyond the −35 dB step of the referenced curve.

(4) Independent sideband transmitters having two channels by 1700 Hz tones applied simultaneously in both channels, the input levels of the tones so adjusted that the two principal frequency components of the radio frequency signal produced are equal in magnitude.

(5) Independent sideband transmitters having more than two channels by an appropriate signal or signals applied to all channels simultaneously. The input signal or signals shall simulate the input signals specified by the manufacturer for normal operation.

(6) Single-channel controlled-carrier transmitters in the A3 emission mode—by a 2500 Hz tone.

(c) For measurements conducted pursuant to paragraphs (a) and (b) of this section, all calculations and methods used by the applicant for determining carrier power or peak envelope power, as appropriate, on the basis of measured power in the radio frequency load attached to the transmitter output terminals shall be shown. Under the test conditions specified, no components of the emission spectrum shall exceed the limits specified in the applicable rule parts as necessary for meeting occupied bandwidth or emission limitations.

[39 FR 5919, Feb. 15, 1974. Redesignated and amended at 63 FR 36599, July 7, 1998]

[WA2OLZ]

W2UD - you have just opened a whole new world of government-speak for me to wade through. I've been licensed for over 50 years and embarrassed to confess I never before heard of Part 2. Obviously I have a lot more reading to do!

Thanks & 73
Jack
WA2OLZ

[k7pp]

Mike;
The only thing I see addressing power output is 97.313,b
Good engineering practices can be found in several other sections of the rules as you pointed out.
Your examples are a good place to go to find them.   
If I were to be inspected,  could I be held accountable for anything outside of part 97?
If I were,  should it not be part of the Amateur Radio license test? 
At the time I got my Commercial license,  there were no Amateur part 97 questions in elements 1-4,  which meant I was not expected to know them.
If I were inspected,  could I not indicate I would be willing to acquiesce to the wishes of the inspecting officer while pointing this out, citing I had made a good faith effort to abide by the letter of the law?
(don't mistake this as being argumentative,  I am just interested in my options)

The FCC was beyond vague when they wrote the part 97 rules concerning power.  They never did get around to stipulating where the power was to be measured.  The answer is spelled out in other parts of the rules concerning Land Mobile but so are allot of other rules non binding as far as Amateur Service.

I just got through reading through part 97 again this evening and just haven't found anything that addresses this and unlike Part 90 which does and goes into great detail as you pointed out,  is it
binding to Amateur operation?   


Respectfully,
Pete

[Opcom]

I'd be OK if an FCC inspector wanted to see my station.

Anyone who worries should be prepared to be measured at the transmitter. I believe they have the equipment to test a transmitter with built-in tuner or open-wire feed ceramic insulators, etc. just need a voltmeter, ammeter, and phase meter. I bet it is all inside one expensive instrument with a handle on it.

The FCC also can take field strength measurements. That way, a difference between a 3000W and 1500W signal is possibly evident, and someone who is tricky with a secret switch or the turn of a variac wheel may still be found out or cause suspicion if the field strength suddenly is changed.

At some point, one could ask, what could be wrong that would cause the FCC to send an inspector to my station?

I don't think it is for having some unintentional 1800W peaks, or some occasional splatter. It is not for the slightly incompetent or occasionally careless operator. It is for intentional scofflaws, trouble makers, and for checking on RFI complaints.

[KF1Z]

Not sure that I understand what is so confusing about "where to measure transmitter power".

and.....

ignorantia legis neminem excusa     

[WD8KDG]

Mike;
The only thing I see addressing power output is 97.313,b
Good engineering practices can be found in several other sections of the rules as you pointed out.
Your examples are a good place to go to find them.   
If I were to be inspected,  could I be held accountable for anything outside of part 97?
If I were,  should it not be part of the Amateur Radio license test? 
At the time I got my Commercial license,  there were no Amateur part 97 questions in elements 1-4,  which meant I was not expected to know them.
If I were inspected,  could I not indicate I would be willing to acquiesce to the wishes of the inspecting officer while pointing this out, citing I had made a good faith effort to abide by the letter of the law?
(don't mistake this as being argumentative,  I am just interested in my options)

The FCC was beyond vague when they wrote the part 97 rules concerning power.  They never did get around to stipulating where the power was to be measured.  The answer is spelled out in other parts of the rules concerning Land Mobile but so are allot of other rules non binding as far as Amateur Service.

I just got through reading through part 97 again this evening and just haven't found anything that addresses this and unlike Part 90 which does and goes into great detail as you pointed out,  is it
binding to Amateur operation?   


Respectfully,
Pete

Prego! Its in there Pete. I didn't bring the regs back to the house; but it said, at the output of the transmitter. To me that means make the measurement between the transmitter and feed line.

The real issue is how to make the measurement, not where. At the date the change was made to PEP, little or nothing was on the amateur market that could. (or that most amateurs could understand) So here we are beating the dead horse again.

The ARRL and FCC blew it; should of stuck with a plate voltage meter & amp meter. Then of course we wouldn't anything to gripe about.

73's
Craig

[k7pp]

It's my fault,  Craig.  I just didn't ask the question properly.

In this day and age,  the output of the transmitter may be hard to define.
You and I think of it as a Box with an SO 239 on it.
Anything past that Box is the output.
 Really?
In a solid state rig,  the PA could be in a tower mounted
Box with zero feed line between the output and the antenna.
Is the last box along the transmission line the transmitter output?   Think about it a minute.
If it was,  what would it have to have in it to be considered the transmitter output?
An exciter?  A PA,  A tuning unit?   Dunno...
You could run the legal limit to the wire in this configuration or run
two thousand watts out of a box on the ground and suffer enough feed line loss to put
you well under the limit at the end of the feed line.
So,  what is the FCC really interested in?

They understand this issue as in an AM part 15 transmitter running 100mw,  the antenna is limited to 9 meters (excluding anything under ground)and the FCC stipulates that any feed line involved is part of the overall antenna length.
That's why manufacturers of LPB equipment make the actual transmitter to mount at the base of the antenna in order to be able to radiate over the entire 9 meters.

I'm thinking the FCC needs to take a look at the rules and nail a few things down but every time they do,  it's not going to go well for us so I'm just going to keep my mouth shut. Hi
I was just looking for a possible different take on current thinking.
I must have given the wrong impression as I'm not trying to get away with anything.  If I were,  I'd just do what others have done and not asked but I really do value the opinions on this board.  Unlike others,  most of the guys here have had some real "up to their elbows" experience and know a thing or two.

Pete

[M1ECY]

Could you not just contact the FCC directly, and ask for clarification?

We had similar problems over here with specification of Foundation License approved equipment - there was, and still is a grey area regarding modified commercial VHF sets - because these sets were not as the manufacturer let them leave the factory, the letter of the license conditions forbids Foundation licensees from using transmitters of this type.

Frustrated by the conflicting views, I contacted OFCOM (our version of the FCC) to get the situation clarified, by return, I was sent a full, and clear to understand position from them, which effectively spells out that FLs are not allowed to use these sorts of equipment on the air, full stop.

I would have thought the FCC, who by the sounds of things are a whole lot more effective than our OFCOM would be more then happy to explain in a language that is simple to understand their requirements - typical government department documents are far too self contradictory.

[K4RT]

If the regs are not specific, then you've got some wiggle room. My suggestion is to leave it alone. Contacting the FCC runs the risk of giving a bureaucrat a reason to draft an NPRM.

[WU2D]

The FCC rules and the rulemaking process are confounding, imperfect and actually represent a living record of ideas, technological progress, best practices of fairness, democracy, individual power and big think. Some rules are legislative but many are interpretive only. Virtually every company I have worked for has kept an FCC lawyer or expert legal firm on a retainer. You can do it yourself or you can use labs and lawyers. There is no one crisp answer on many issues. As there is no one answer, many times research and experience rule the day. If so and so got warned or fined, our company may get warned or fined...When you deal with case law, politics and fairness in an open system of experts, volunteers, lawyers, legislators, broadcasters, government safety the FAA and other users and manufacturers (many or most of whom are hams), crazy things get put into the rules.

[WD8KDG]

It's my fault,  Craig.  I just didn't ask the question properly.

In this day and age,  the output of the transmitter may be hard to define.
You and I think of it as a Box with an SO 239 on it.
Anything past that Box is the output.
 Really?
In a solid state rig,  the PA could be in a tower mounted
Box with zero feed line between the output and the antenna.
Is the last box along the transmission line the transmitter output?   Think about it a minute.
If it was,  what would it have to have in it to be considered the transmitter output?
An exciter?  A PA,  A tuning unit?   Dunno...
You could run the legal limit to the wire in this configuration or run
two thousand watts out of a box on the ground and suffer enough feed line loss to put
you well under the limit at the end of the feed line.
So,  what is the FCC really interested in?

They understand this issue as in an AM part 15 transmitter running 100mw,  the antenna is limited to 9 meters (excluding anything under ground)and the FCC stipulates that any feed line involved is part of the overall antenna length.
That's why manufacturers of LPB equipment make the actual transmitter to mount at the base of the antenna in order to be able to radiate over the entire 9 meters.

I'm thinking the FCC needs to take a look at the rules and nail a few things down but every time they do,  it's not going to go well for us so I'm just going to keep my mouth shut. Hi
I was just looking for a possible different take on current thinking.
I must have given the wrong impression as I'm not trying to get away with anything.  If I were,  I'd just do what others have done and not asked but I really do value the opinions on this board.  Unlike others,  most of the guys here have had some real "up to their elbows" experience and know a thing or two.

Pete

Hi Pete,

I hear you. In just about any case, wouldn't the FCC measure the power (PEP) of the final PA? (amateur use, Part 97)  Doubt that Binh Nguyen, the Resident Agent here in the PNW, would accept my PEP output from the VFO of the Ranger used as the exciter of the Johnson Desk KW. HI

All this PEP stuff needs to be kept real simple. A KISS level is needed for some, gotta only have to watch the munkey swing the needle. Needle points to 1500, you are there.

As others have stated before; the RF output of some transmitters aren't 50 ohms, etc., & this opens other cans of worms. Don't poke the FCC in their eyes, giving them a reason for a visit.



73's
Craig

[k7pp]

You've got a good point,  Craig;

Well,  as I said, I value input and hence the question.   I don't have all the answers.
I do have an interpretation and I suppose if visited by an FCC inspector,  the worst that could happen is
he could disagree with me.  In that case,  I would adjust or align in such a manner as to conform to his
take on the situation.   Then,  I could take it up with a request for rule making.
Doing so ahead of time always seems to get the Ham on the short end of the stick, so to speak.

Thanks all for your input.

Pete

[KA7WOC]

Interesting discussion you have started Pete.
I deal with a different federal regulatory branch using CFRs.  From phone calls to DC years ago a learned that the regulations are always written purposely vague.  This is because it is very seldom that any two cases are identical.  By keeping the rules vague the inspector has leeway to interpret.  In my case the onsite inspector usually has the last word.  Even when I talked with the fellow who wrote particular paragraphs and got his exact intentions the local inspector's interpretation was what I had to live with.

[WD8KDG]

Pete,

Binh has been to my shack twice in the last couple of years. As you know the Part 15 RFI sux here in Springtucky. All the grow lights drive me crazy. I pushed the issue of RFI and that put me on the radar. Binh monitored my transmissions as well and I bet you he had the equipment in his vehicle to measure the frequency, band width, and power level without having to be at the shack.

Binh mentioned both the RFI & my station info on his visits. I was running legal power, etc; but Binh has to look at both parties. Be careful when poking the FCC in the eyes.

Craig,

[Tom WA3KLR]

We've hashed over this topic before in the AM forums.  Here is one thread and it has links to other threads as well.

http://amfone.net/Amforum/index.php?topic=20087.0

Happy New Year.