What does the FCC really mean?

[Tom WA3KLR]

From Title 47 (Telecommunications) Chapter I (Roman numeral one) of the Code of Federal Regulations  
(10–1–10 Edition).  Chapter 1 is for F.C.C.

PART 97—AMATEUR RADIO SERVICE

Part 97.3  Definitions

97.3(b)(6) PEP (peak envelope power). The
average power supplied to the antenna
transmission line by a transmitter during
one RF cycle at the crest of the
modulation envelope taken under normal
operating conditions.

So power is measured where the transmitter meets the transmission line.  This is the transmitter output.  Can't be plainer.  If the impedance at this point is other than 50 Ohms then the power measurement may not be convenient for most people.

97.313 Transmitter power standards.
(a) An amateur station must use the
minimum transmitter power necessary
to carry out the desired communications.
(b) No station may transmit with a
transmitter power exceeding 1.5 kW
PEP.
(c) No station may transmit with a
transmitter power output exceeding 200
W PEP:
(1) On the 10.10–10.15 MHz segment;....... and on and on with specific band limitations.

[M1ECY]

Well, that seems clear enough to me - certainly leaves no question that the power is measured at the entry point to the antenna feedline.

Looks like the lowest loss feeders are the way forward to make the most of everything.

[WA2OLZ]

"From Title 47 (Telecommunications) of the Code of Federal Regulations Chapter I (Roman numeral one) (10–1–10 Edition)"

Spot on. That resolves (and dissolves) any mystery.

[W1ITT]

I have seen fairly recent FCC reports of visit to CB stations where they speak of a linear amplifier, and state that it was warm to the touch, indicating recent operation.  I wonder how long it's been since the inspector teams actually hitched up a Bird wattmeter or an oscilloscope to anyone's output terminal.  Legend has it that the Commission went to the output power standard so that inspectors wouldn't have to reach into someone's homebrew glomming amplifier with meters to measure voltage and current.
I have thought if one wanted to run illegal power (perish the thought) that the way to do it would be either to run some 90 ohm Russian coax with some of their arcane connectors to which no adapters exist, or else to run a balanced wire output from the transmitter, of some odd unspecified impedance, into a load that was purposely reactive. 
I recall when I was a Novice, occasionally running a DX-60 at 90 watts input, up past the red line that indicated 75 watts input.  But, realizing that the FCC vans were always lurking just around the corner, I cranked the power back pretty quickly, thus saving myself from a lengthy residence at a Federal house of corrections.  Back then, I believed!

[wa3dsp]

While it is measured at the transmitter output may I remind you that the difference between 1500 and 2000 watts is barely noticeable if at all noticeable at the receive end. On the other hand your electric bill will go up and your equipment reliability will go down.  So trying to get a few extra watts at the 1500 watt level is fruitless.

Good antennas and transmission lines are important to get that power to the ether. A 3db gain antenna is sure cheaper than running an additional 1500 watts.


Happy New Year!

[Steve - K4HX]

I've been aware of hams using 1 kW broadcast transmitters on the amateur bands since the 1980s. This amounts to easily several dozen (at one time there was a list of close to 100 but not all were 1 kW). I've never heard of one being inspected or fined.

[W1RKW]

I have to concur with similar comments regarding behavior and the FCCs response to complaints of such.   The current and most often MO is squashing complaints of malicious interference if one reads the FCC website. Unless a complainant can prove another amateur is running "obscene power" (a term coined by W2VJZ) the FCC will not go out of their way to bring out the equipment to test your station. 

[KF1Z]

I've heard story that said the fellows in the black vans pulled in... asked the
station operator to transmit....
Yup 1400 watts output... you're good.

Of course this was in AM... nothing but carrier, no modulation   

[wa3dsp]

Well again I go back to what the heck difference does it make. If we go by the common definition that 1 S unit = 6dB   then at the 1500 watt PEP level you would have to run 6000 watts to gain 1 S unit. Hardly a worthwhile use of power. As we go up in power the required power vs. gain gets crazy. At 50KW a 1 s unit gain would require 200KW. On the other hand at lower powers you can achieve a lot of gain with modest amounts of additional power.  From 5W to 80W is 12dB or 2 S units.

[k7pp]

"what difference does it make"?
That's a fair question.

1/2 an S unit up from the noise floor can make the difference you're asking about.
If you like to DX, like I do then higher power is very helpful.

As far as "enough power needed to maintain communication" goes,   it's hard to quantify if you're calling CQ or contesting.   By the time you figure out what the appropriate power is, the QSO is over.

The original intent of the post was to try and find out what my fellow hams thought might be the FCC's
standard as the location where power output should be measured.  In many broadcast installations,  an RF ammeter is located at the base of each tower.   Since the base impedance of the tower is known and part of the station proofs,  power to each antenna is easily calculated.    

If I had read the "definitions" section as one poster pointed out,  I would have found my answer.
The FCC want's to measure power output on the back of a "box" at the hams station.
They could care less how much power is delivered to the antenna.   I get it.

Having undergone no less than 31 inspections over my Commercial Career, I can tell you that in 90 percent of the cases,  the inspector just wanted to look at the paperwork to check license expiration dates.  The other 10 percent involved Intermod complaints and in one case interference to a cordless telephone.  We hardly ever went to any of the many hundreds of paging transmitters I supervised.

I see a close parallel to running high power to those in my classic car hobby.
Many spend many thousands to squeeze just another few horsepower from an otherwise very adequate engine.  Quarter mile improvements could be measured in the 100th's of a second yet,  it was done as part of the joy of the hobby.

Having the ability to run the limit is part of the "joy of the hobby" for me.   I also don't have any problem with those who like to run a couple of watts because it doesn't make any difference to their operation.  I admire their dedication.   There is something compelling about talking 1000 miles on a few watts, so I understand.  It's just not for me.
Thanks to the posters for helping me understand how my peers see this.

  

[Steve - K4HX]

All true but completely irrelevant for 99% of AM operation. I'm pretty sure that you're not running AM to work DX that is 0.5 dB above the noise floor. 

[k7pp]

" work DX that is 0.5 dB above the noise floor"

Just for clarification,  Steve,  I referenced 1/2 S unit or 3 db not .5 db.

Not that anyone needs my approval, but I support anyone operating low power 100 percent.

[Steve - K4HX]

I'll amend my statement - I'm pretty sure that you're not running AM to work DX that is a 3 dB above the noise floor. My point remains the same.

That said, I've worked a fair amount of DX on AM. Some of those stations had high power, some didn't. Most had better than average antennas. The notable exceptions were on 10 meters where both low power and average or below antennas are often involved. But these were only when the band was hot. When it's so-so, the guys with the yagis and power stand out. In other words, the antenna is usually more important than the power. If you have both, you have it all.

And I do approve of those who run high power 100 percent of the time!     And my ears are very thankful.

Hope to hear your big rig on the air soon.

[k7pp]

Well,  Steve,  I should start a new post but it's interesting you bought that up.  I'm located in Western Washington out on the Coast.   I HEAR lot's of stations on the East Coast and even down into some of the Southern States.  I also hear folks I normally talk to in Eastern Washington and Oregon work them from time to time.
I normally run about 145 watts with my old Valiant and it does a fairly good job.   I hired a tree climber to hang my dipole at 153 feet and it matches perfectly on 3870 with no tuner.   
Most of the East Coast guys are S4 to S6 here and my noise level is usually an S3.
They don't hear me at all.  Not even a whisper.  I've even resorted to being polite and using good operating practices....Hi
The locals here me fine on either my 40' dipole or my 153' dipole.   There doesn't even seem to be much difference in the antennas close in.
So,  You see,  I have taken the antenna thing to heart.   I'm just not sure what else to do besides more power.
It makes me wonder what those guys are running back there.

[Steve - K4HX]

You will hear the guys with the better antennas, at least most of the time. Most people are running antennas (usually dipoles) at 60 feet or less. The guys with the dipoles at 80-90 feet stand out at the longer distances. I've also used a K9AY and a Beverage on receive to reduce the noise floor and pull out more stations.

Some of us on this end of the continent have made specific efforts on 75 meters to work the west coast on several occasions throughout the winter months in recent years. Unless the conditions are exceptional, only those with high antennas and/or good locations are heard or relatively easily heard on this end. Sometimes signals are extremely strong. I've worked stations from the northwest that were 5/9+20-30. On one exceptional night, I worked a 7-land station, even though I had mistakenly tuned up into my 160 meter coax-fed dipole!

I'm sure that I will be able to hear you, given your set up.

[flintstone mop]

I've been aware of hams using 1 kW broadcast transmitters on the amateur bands since the 1980s. This amounts to easily several dozen (at one time there was a list of close to 100 but not all were 1 kW). I've never heard of one being inspected or fined.

Very true! The FCC is looking for the band polluters that are running way in excess of our little 1.5KW P.E.P. power. The folks who interfere with other services.
Running anything past 2KW of carrier really stresses typical Ham radio antenna systems.
Running a 1KW AM carrier vs a 375 W carrier is not worth the electricity to produce that small increase. No one on the receiving side will notice a difference. Now a 5KW carrier will be noticed.
I have used broadcast transmitters at 250 W and get excellent reports. The secret will always be the antenna.
A short dipole 30 feet high off the ground going through most cheap tuners on 160M, is not an antenna.
Read Steve's (K4HX) other replies.
Fred

[k7pp]

Well,  perhaps you're right, Fred.  I have this vision of a couple of guys in suits pushing
my 1500 lb transmitter into the back of a white van.
Maybe I should re-think running a broadcast transmitter and stick to my little Ranger.
I'd hate to be known as K7 Power Pig or K7 Peter Polluter,  Hi

Pete, K7PP

[W3RSW]

Pleased to meet you Kryptonetic Seventh Popular Person ! 

Bet Ur 1.5k lb. baby really sounds FB.

[flintstone mop]

Well,  perhaps you're right, Fred.  I have this vision of a couple of guys in suits pushing
my 1500 lb transmitter into the back of a white van.
Maybe I should re-think running a broadcast transmitter and stick to my little Ranger.
I'd hate to be known as K7 Power Pig or K7 Peter Polluter,  Hi

Pete, K7PP

NOPE! always run high power. 25 watts is a big struggle on AM, unless you have a helluva antenna system.
The band polluters are the ones who operate their equipment with all knobs full clock-wise and overdrive the linear amp. The CB types with poorly designed transmitting equipment.
Fred