What is definition of Transmitter?

[KO6YB]

Hello AMForum,

The FCC law states the maximum PEP of ham transmitters at 1500 watts  . The seems to not include loses in an (external) antenna tuner and feedline and or balun loses, as these ARE NOT part of the transmitter.

What limits apply in a phased array where (in this instance) each antenna element is powered by it's own PA amp, or even it's own transmitter so as to achieve adjustable phase and amplitude? This could be four, six , or ? number of "transmitters". I am going to guess the sum power must not exceed the 1500 PEP. But, this does seem counter to the "understanding" that it is the one-box "transmitter" that the power limit applies to. Does the FCC have any rules on this instance?

Thanks, Stan

[WD8BIL]

The seems to not include loses in an (external) antenna tuner and feedline and or balun loses, as these ARE NOT part of the transmitter.

No, they are part of the antenna system.

[KA0HCP]

Phased arrays and remote multiple transmitters are not specifically addressed in Part 97.   The logical extension of the 1500w rule is that the sum total output of the transmitters is limited to 1500w as well.

Antenna systems and accessory losses don't change the transmitter power output limit.

Two examples show that the FCC does recognize the difference between transmitter power output and overall system output.   First is the 50w ERP reference to dipole, for 60m.  And the other is the discussions regarding the coming 630m band with limits of 1w or 5w ERP referenced to Isometric (can't think of correct term) as defined by ITU.

[W3RSW]

All following is my opinion only: Parsing definitions beyond "Forest through the Trees" can get one confused. In addition to others' thoughts:

"Antenna" means the composit of all the elements, regardless of type.  Could be a plethora of rhombics or phased arrays separated by wavelengths.  The combination is the antenna. Here your allowed almost unlimited experimentation.

"Transmitter" means a composit of all the final active elements, be they separate tubes or transistors  in PP or PP parallel feeding a combiner of any sort, on one board or a combination of other boards having their active devices through their remote combiners feeding separate elements of antennas hooked up with coax, in proper phase, etc.  

As far as phase goes, anything out of correct phase or to to the wrong element or sets of elements will get you a radiated power reduction, hence it always behooves you to make sure all phases are where they're supposed to be anyway, whether fed by separate boards or one.

In summary, if you truly want separate transmitters on separate boards  feeding separate antenna elements with all the concomitant complexity and cost of exact frequency timing, component phase timing synchronization, split power supplies, you name it, etc. between possibly several wavelengths separation, then your probably applying for the recriprocal of radio astronomy experimental reasons anyway,  hence an experimental license where you can define your request for greater than 1500 PEP per board or sets of boards, or are power and /or heat dissipation limited for the final devices chosen.   This applies in the digital world too.  Mode and pulse class too.  There is always an upper limit for a device, Class E or otherwise.

Phased arrays as in Navy destroyers' radars are for specific purposes. If you want to duplicate this for directive amateur arrays hence beaming your signal, then sky's almost the limit in enhancing your ERP through antenna experimentation  Antenna cost probably goes up as a cube function of complexity compared with the essentially one dimensional doublet.  

But hey, there's little but bureaucratic and cost nightmare from keeping you from pushing the envelope. Just be aware that every push results in further restriction of definition by adverse ruling and what you thought of as friendly parties in response.  

[flintstone mop]

In the U.K. a transmitter is a SENDER

[w4bfs]

a real transmitter is a maul

[DMOD]

Hello AMForum,

The FCC law states the maximum PEP of ham transmitters at 1500 watts  . The seems to not include loses in an (external) antenna tuner and feedline and or balun loses, as these ARE NOT part of the transmitter.

What limits apply in a phased array where (in this instance) each antenna element is powered by it's own PA amp, or even it's own transmitter so as to achieve adjustable phase and amplitude? This could be four, six , or ? number of "transmitters". I am going to guess the sum power must not exceed the 1500 PEP. But, this does seem counter to the "understanding" that it is the one-box "transmitter" that the power limit applies to. Does the FCC have any rules on this instance?

Thanks, Stan

Let's look at the Systems view and then look at precedence:

An AM broadcast RF transmission system is shown below in the pdf file.

The transmitter is the RF generating subsystem that is defined with respect to total power output, modulation, emissions, etc.

The precedence for defining transmitter characteristics and performance is found in FCC Parts 73.14 to 73.15 (and other parts) where the transmitter characteristics are well defined.

Therefore, the power output of the transmitter is defined.

The Effective Radiated Power (ERP) is the total power in a specified direction which is determined by power division, phasing, and orientation of the antenna system. So we should differentiate transmitter output with total ERP.

Now, as to the actual meaning of the 1500 Watt PEP figure, and as to how it is to be interpreted, well, we have had numerous discussions on that topic as can be found by searching.

Phil - AC0OB

[W3NE]

This is why the law profession is growing so rapidly.

Bob-NE

[w1vtp]

Hello AMForum,

The FCC law states the maximum PEP of ham transmitters at 1500 watts  . The seems to not include loses in an (external) antenna tuner and feedline and or balun loses, as these ARE NOT part of the transmitter.

What limits apply in a phased array where (in this instance) each antenna element is powered by it's own PA amp, or even it's own transmitter so as to achieve adjustable phase and amplitude? This could be four, six , or ? number of "transmitters". I am going to guess the sum power must not exceed the 1500 PEP. But, this does seem counter to the "understanding" that it is the one-box "transmitter" that the power limit applies to. Does the FCC have any rules on this instance?

Thanks, Stan

Stan

What an interesting comment.  There is a technique where an exciter illuminates hundreds of elements in a phased array.  These elements in turn feed power amplifiers which in turn reradiate to elements that are rotated 90 degrees (orthogonal to the receive element).  These elements are in turn controlled with it's phase and amplitude so that a very strong beam is formed. 
 
I wonder how a visiting FCC unit would measure the total power of such an array?

Application?  How about radiating the moon with this very powerful beam so that folks listening to this signal could hear it with a small beam pointed at the moon.

Al

PS: My emphasis of quoted comment.

[Opcom]

This discussion comes up from time to time and always reminds me of the Kabuki where the actor's mask changes from the nice guy to the demon and back. The station can not hold up a 4500W mask when rag chewing and then quickly grab a 1499W mask when the inspector comes to visit.

In enjoying the Kabuki, the audience suspends its belief during sudden and odd changes in a character, but at a ham station the FCC is not present for its enjoyment and not likely to suspend its belief when something seems strange.

There should be a goal of having the station to where, if or when the government wants to inspect it, it will meet the rules.

While a set of transmitters each making 1500W might not get a citation right then, the official who is not satisfied or who is befuddled by a scientifically bizarre station would likely be coming back later with someone competent to decide what you are doing right or doing wrong.

That includes measuring power at non-coaxial/OWL outputs of transmitters, if indeed they feel it is worth the trouble, or maybe they just see 3500W input and cite. Or maybe they just add up the watts driving each antenna. Then you got to answer the letter and explain. Some things are not worth doing. Tricking the FCC at the risk of the license is one, and cheating on the wife or one's taxes is another.

That's the crux of the biscuit. They decide if the station is operated right or wrong. No Kabuki.

[W3RSW]

Precisely.

[WD8BIL]

Well there's nothing wrong with running multiple legal limit transmitters simultaneously. Contest stations do it all the time.

But I suspect running multiple legal limit transmitters in a SINGLE system would likely be deemed a no no.
 

[W3GMS]

My belief is that the FCC intended it to be the power out of the transmitter / amplifier.  That is why as users try to pick low loss transmission lines and efficient devices further down the line between the output of the power generating stage and the antenna. 

If I remember right, the FCC went to the output power rating so it could be measured "easily" at the station with a power measuring device as compared to the power input method requiring intercepting high voltage and high current paths.

I would suspect that if the FCC wanted to inspect ones station, they would come with their own watt meter and dummy load and connect it to the last RF generating device in the transmitter chain.

73,
Joe-W3GMS     

[flintstone mop]

My belief is that the FCC intended it to be the power out of the transmitter / amplifier.  That is why as users try to pick low loss transmission lines and efficient devices further down the line between the output of the power generating stage and the antenna. 

If I remember right, the FCC went to the output power rating so it could be measured "easily" at the station with a power measuring device as compared to the power input method requiring intercepting high voltage and high current paths.

I would suspect that if the FCC wanted to inspect ones station, they would come with their own watt meter and dummy load and connect it to the last RF generating device in the transmitter chain.

73,
Joe-W3GMS     

This is interesting  Joe,
I have tried these experiments at my station into a dummy load. TX set for 375 watts carrier and a run-of-the-mill Bird watt meter with peak reading capability. Voice modulated with audio processing on and a reliable AM mod monitor (REA AM monitor) showing 120% pos peaks and about 97% neg and the peak reading meter never gets close to 1500 PEP. Even making a steady sound with my voice in the mic.
Now, I injected a single tone into the system and adjust modulation for the above mod monitor readings and that peak reading meter is right there close to 1500 P.E.P.
We know that it would be an extreme rare moment that the FCC would ever visit a Ham station, unless there were serious RFI to an emergency comm system, or a Ham op is running excessive power, like 10kw.
And running extreme power takes serious hardware to handle that amount of RF. SWR at any level is a disaster!!!

[KO6YB]

The Group, thanks for the replies and humor. the question was an "easy" one. As for the comments that it is the output of the final or collection of final output devices seems reasonable but not completely. Just as it was stated, if the FCC were to come out, with a dummy load and measurement equipment, it would not be hooked up to the final tube(s) or transistors. It most likely would be the output connection the transmitter assembly and most likely 50 ohms. I am not sure I have seen a tube with a 50 ohm output impedance. So, if the output network in the transmitter box is more of an antenna tuner, I believe its losses would also factor into  to the measured output. If an antenna tuner were a separate box, then it would not count. My thinking is that each phased antenna was an antenna on its own, each free stand vertical, no mechanical linkages. Thanks to kb4qaa.

W3RSW, thanks for defining Antenna. So, it is most properly called a phased array antenna rather than a phased array of antennas. View point makes a difference. Yes, there are complications to such an antenna, beyond the scope of the question at hand.

Law profession? Do not get me started.

Al, radiating the moon. I don't know if I could get a sharp enough beam. I have tried it with my led flashlight, but could not detect any results. Maybe I should have waited a few seconds. No, maybe I should have waited for a full moon, so I could see where I was aiming.

Actually I have now been shamed by this reply. I had considered downing pigeons with focused megawatt pulses from parallel 4cx1000s cooled by cylinders of dry ice pushing down on each anode. OK, I won't. But is was tempting.

Yes Beefus, it is a maul. A bean only diet can drive one to such thoughts.

Opcon, I think your very wrong with this Kabuki analogy and mask changes. It happens all the time when the IRS knocks at a door and states we are here to help you, with a pleasant face and smile. Right. That too can change very, and you will suspend disbelief.

WD8BIL, so was my guess as I elaborated on the title question. Just not sure the reasoning.

I must admit, the collection of responses was a laugh, and it keep going for a few days. such exuberance rhetorical wit going in so many directions.

Actually I have not intent, no need to exceed the legal output power, nor cause any adverse ruling to the hobby. Pigeons or not. Perhaps they might land on the end of a dipole. Other hams have built phased arrays for HF. There is an extra acre in my back yard doing nothing but vegetating. I am in the country, up at 3000 feet. Some peaks in the distance but view good low horizons in most directions.

After looking at how some phasing is attempted with coax delays, and RF power splitting, RF power switching, large amount of Expensive L and C networks, the idea of using solid state 200-300 amplifiers at each antenna feed point looks nice. Such devices as gang able sync'd DDS and being software adjustable, to provide phase and amplitude such seems doable. And I like AM, always did.

I have recently received a large amount of 500 and 750 hardline, will use to make upcoming ant project.

Thanks for the responses.
Stan KO6YB

[Pete, WA2CWA]

I am also interest in putting up (first) a turnstile for 80 / 40 using fan dioples,
have not seen on the internet anybody doing that.

Stan KO6YB

I would suggest starting a new topic for this question. Makes it easier for members to track and respond to interests.

[KO6YB]

thanks, I agree. I will modify it out. Will post it when time permits.

[Opcom]

I believe you misunderstood what I wrote. The reply to it does not make sense the way it is worded. Anyway a hypothetical question like that is always a parlor game. The real interest here is in practical applications so if you have some interesting work going on and want information exchange then be sure to post the details as well as results of your experiments in the new topic so all can see what's being accomplished.

[w4bfs]

......Yes Beefus, it is a maul. A bean only diet can drive one to such thoughts.....

Stan KO6YB

perhaps but much more noticeable are the smoke detectors going off .....

[W1ITT]

I think everyone knows the intent to 97.313 even if the wording is not precise enough to save it from curious parsing.  I recall that when power was stated as input, it was input to the stage "or stages" providing power to the antenna.  A select few ran cathode driven amplifiers with very QRO diver stages, and the drive power was mostly passed on to the antenna, but the meters on the final showed something that appeared legal.
If one wanted to make things difficult, he could build a California Kilowatt with balanced line output, matched to some odd impedance or, if unbalanced, use some strange Eastern Bloc coaxial cable of some non-50 ohm impedance with some of the unfamiliar connectors that I have seen in that part of the world.  I suspect that the Field Engineers come with a 50 ohm Bird wattmeter, a few slugs, and some type N to UHF adapters, or maybe even 7-16 DIN if they are well provisioned.
That having been said, while I watch the FCC proceedings, I can't remember the last time I saw anything of the FCC busting a licensed Amateur for QRO.  They have bigger fish to fry.  But it's all fun to contemplate over a frosty beverage.

[KD6VXI]

I was visited at 17 years old because my radio was causing interference to my neighbors (also the landlord and owner of the property both houses sat on).

They did show up with a Bird and an assortment of slugs.

--Shane
KD6VXI

[DMOD]

Well, for me it was at 14 YO.

They visited my dad while I was at school.

Dad said, "I don't know what they meant, but they said you need to clean it up."

So I added some filtering and "de-turboed"   my Eico 720.

They never did ask to see the rig.

Phil - AC0OB

[Steve - K4HX]

If the FCC thinks that you are running illegal power, they will take a field strength measurement before they visit you. Even if you did the kabuki, they would know, since the FS would be lowered.

That's said, unless you are bringing attention to yourself in other ways (illegal operation in some other way, being obnoxious on the air, wide/splatter, etc), the likelihood of ever being busted for illegal power is about the same as being stuck by lightning.

[KO6YB]

Hello Phil, thanks for the account from your teens. Nice to know some in the FCC used just enough "encouragement" instead of a too heavy handed approach.

Stan

[W3RSW]

Well if the FCC does field strength measurements before the visit, let's hope they're smart enough to realize if they're in front of the beam of a phased array, or off the sides or back. Let's hope They're smart enough to realize that you have a switching system and what set of phases it was set on when they took the readings.  Perhaps they'll just measure your transmitter or combined sets of transmitter outputs and call it a day.  Sooner or later your conglomeration of 600, 450, 300 and 75 ohm lines will frustrate them into probably making a poor decision for you if your phased array isn't one of the standard and easily modeled types.

If not, Let's hope the Bird / ERP formulae DF'ing (humor)!engineers are willing to commit the time to measure all you possible phase lash-ups if you have a complex antenna, the down field complainers in relation to your field and then tell them to go pound sand.

Would be helpful if one of the inspectors was a knowledgeableham. --Yeah, right.
You as a ham don't have any specific phase distribution directions to observe unless you've been assigned such by order for specific past interference problems.  They've also assigned time slots, quiet hours, etc., but that's another topic.

Darn iPad, took to long to write this well and even that's doubtful.