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Author Topic: Legal Limit on 160?  (Read 41009 times)
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W2VW
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« Reply #50 on: November 23, 2010, 09:15:47 AM »

And some people want to regulate bandwidth Roll Eyes
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WD8BIL
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« Reply #51 on: November 23, 2010, 10:35:28 AM »

The guys in my band have been getting wider the last few years!
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K1JJ
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« Reply #52 on: November 23, 2010, 10:45:11 AM »

http://amfone.net/Amforum/index.php?topic=9216.0

BTW, looks like an excellent thread in 2006 here adressed the peak reading issue. Take a look especially at Stu's measurements. He concluded that the scope method is the most accurate and the Bird (using the aftermarket peak reading kit) read ~200 watts low on peaks when using 1400 watts pep. (About -17% low) Interesting.    

However the good news is the unit by N8LP is very accurate for peak power as agreed upon by both Stu and Frank/GFZ.

See:  
http://www.telepostinc.com/  


I use the scope/formula method for accuracy and monitor the peak Bird but may look into this N8LP unit.  


These power discussions may get lively, but in the end we all do more reading and thinking - that's a good thang.... Wink

T
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« Reply #53 on: November 23, 2010, 11:34:23 AM »

A test method is provided. Measure the average power of one cycle of RF at the peak of the modulation envelope. Pretty simple, most certainly far more simple than the arcance mil-specs.

I requested the FCC provide a test method and a time constant on PEP when they came up with this crazy method. They never responded. In the Mil world a test method is provided.
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WA1GFZ
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« Reply #54 on: November 23, 2010, 11:35:34 AM »

at what time constant?
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k4kyv
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Don
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« Reply #55 on: November 23, 2010, 11:38:52 AM »

I requested the FCC provide a test method and a time constant on PEP when they came up with this crazy method. They never responded. In the Mil world a test method is provided.

That would make sense for measuring average power output, but would be meaningless for PEP. With voice modulation, the average reading meter would be treated much like a VU meter, with a prescribed time constant.  That's the way they prescribed measuring input power for years, by measuring plate current using a DC meter with prescribed time constant. Fluctuations in PEP reading are due to shortcomings in the measuring instruments, and are not inherent to the definition. It is average power (with does fluctuate with voice modulation) that determines how brightly the transmitter lights up a light-bulb dummy load, heats up a resistor, how loud a signal it puts on the air and how much interference it causes, in other words, the purpose of the power limit.  The power at the crest of occasional voice peaks is irrelevant to all the above, except when determining factors like the amount of linear head room available in the amplifier. All told, DC input is a more meaningful measurement of signal loudness than is PEP.  The most relevant method would be to use a true average-reading power meter, like the Bird APM-16. A thermocouple rf ammeter is also a true rms-reading device and thus may be calibrated to read true average power, but is too sluggish for indicating voice peaks.

The Bird 43 does not indicate true average power except when applied to a steady unmodulated carrier or FM or FSK carrier.  It measures average rf voltage, with the scale calibrated in watts into a 50 (or 75Ω) load. With voice modulation such as SSB, it substantially underestimates average power.  Average power is based on rms voltage and current, not average. A true rms-reading meter is a square-law instrument, requiring active devices and is more complex than a simple diode rectifier feeding a DC movement, which reads average, not rms voltage, and this is the case of the Bird 43 and probably all the hammy hambone wattmeters on the market. This explains the higher cost of the APM-16.

This "average" business can be confusing.  Average power = rms voltage X rms current, not average voltage X average current.

The ITU Radio Regulations define the terms Peak Envelope Power, Mean Power and Carrier Power with regard to a radio transmitter. The terms are defined as:
Quote
  * Peak Envelope Power 'pX' (s1.157) means the average power supplied to the antenna transmission line by a transmitter during one radiofrequency cycle at the crest of the modulation envelope taken under normal operating conditions.
   * Mean Power 'pY' (s1.158) means the average power supplied to the antenna transmission line by a transmitter during an interval of time sufficiently long compared with the lowest frequency encountered in the modulation taken under normal operating conditions.
    * Carrier Power 'pZ' (s1.159) means the average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle taken under the condition of no modulation.
http://www.gira.pt/Docs/RR%20Vol1-e.pdf  (Scroll to page 21, pdf page 33)


Strictly speaking, the PEP bullsh!t hurt the slopbucketeers as much as it did AMers, assuming the leenyar is run cleanly without a lot of processing and not driven to flat-topping.

http://vk1od.net/measurement/SsbTxPower/MeasureSSBTxPower.htm
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« Reply #56 on: November 23, 2010, 11:44:34 AM »

Any time constant long enough to measure the average power of one RF cycle.  T= 1/f

at what time constant?
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K1JJ
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« Reply #57 on: November 23, 2010, 12:06:54 PM »

Measuring AVERAGE power as far as regs are concerned is a dinosaur. A standard Bird average reading meter is worthless here. So is a thermocouple. To play their game, we need to add on the peak reading modification board OR get a better, more accurate peak power meter OR use the scope and formula.  The FCC evidently doesn't give a rat's ass about average power anymore. It's a peak game.

As Huzman suggested, like it or not, peak power is the current rule.  It doesn't matter if it's my 12% duty cycle Belcher putting out 180 watts average (1500w pep) or it's a dead carrier or RTTY or CW at 1500w average. Both are seen as maximum power in the eyes of the regs.

That said, we could choose to be either Clark Kent, Superman, The Thing or Spiderman...  or find a way to change the regs back to the old E X I.


Here's my point... load a linear amplifier up to as high as you can with a dead carrier. Push it to the limit right to the point of saturation. Let's say it's 1500 w output dead carrier. Then put in some ssb or AM voice programming. Assuming the audio is at a certain threshold level, there will be SOME voice peaks that hit 1500 w out at their peaks. Add some audio processing to bring the average up to a higher average  level and the voice peaks are STILL never going to exceed 1500 watts out.  So whats the difference between loading an amp up dead carrier and then choosing what density of audio to run? The highest power peaks are the same in the eyes of the regs.


I realize average power is what lights a bulb and all that, but the regs don't use that guideline anymore. Personally, I'd rather see average power used for everything too - it means more.  But if one wants to monitor their compliance, then a peak reading device is required.  Accuracy in the real whirl will vary as we have already discussed.

T
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k4kyv
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« Reply #58 on: November 23, 2010, 12:28:53 PM »

When they passed the new regs, they deleted the requirement for having instruments capable of accurately measuring transmitter output power, an acknowledgement that the procedure would be too difficult for the expected technical expertise of a typical amateur licensee. In the R&O, they stated that amateurs are able "to use means other than accurate measurement to determine their transmitter power".  Elsewhere in the text they stated something to the effect that amateurs would no longer be required to measure power; they would just be required to comply. Go figure.

Under the old rules, accurate measuring instruments were required for DC inputs exceeding 900 watts.  That had little more meaning than the above, since one could always claim to have been running 899 watts, while their "inaccurate" measuring instruments failed to indicate that they were really running 3 kw.

As for time constant for measurements of average voice signal levels, by definition a VU meter is supposed to take "300ms to stabilise, and should show only minor overshoot". IIRC, the FCC prescribed a 250ms time constant for the plate current meter in a slopbucket linear. There is no such thing as mechanical meter movement with a time constant short enough to measure the average power of one RF cycle,  T= 1/f. By the nature of the laws of physics, it necessarily integrates average power taken over the time required for several audio cycles of modulation.
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Don, K4KYV                                       AMI#5
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Steve - WB3HUZ
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« Reply #59 on: November 23, 2010, 12:40:00 PM »

Quote
There is no such thing as mechanical meter movement with a time constant short enough to measure the average power of one RF cycle,  T= 1/f. By the nature of the laws of physics, it necessarily integrates average power taken over the time required for several audio cycles of modulation.

Sure, if you use the meter to directly make the measurement. Remember, a meter is just an indicating device, not a measuring device. A powered, peak reading circuit can make the measurement and drive the meter. It's been done for decades.
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« Reply #60 on: November 23, 2010, 12:42:43 PM »

My point exactly Don. Even 1/F is too fast as Mr. Nyquil would tell you
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« Reply #61 on: November 23, 2010, 09:22:43 PM »


...That said, the real issue is not how accurately we anally measure 1500 watts pep. It's really about our intentions as shown by the size of the finals and infrastructure we run in reality.  For example for ssb, a pair of 3-500Z's says one thing. A pair of 3CX-3000A7's says another... Wink  
  
T

I really can't agree with that statement, even with the sly smilie.

The person that previously owned JAWS II the 3CX3000A7 amp was using SSB and the story is that it was built and then used to "prove a point". I have no more info on what point. The only point really available for examination was that someone did excellent work.

How many SSB 3CX3000's does it take to equal an AM BC rig? It appears the question of tybe types is a sacred cow that is best left undefiled. Otherwise before we know it, people will be arrested for felony posession of shoestrings.


* shoestring_letter.jpg (133.13 KB, 650x842 - viewed 636 times.)
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« Reply #62 on: November 23, 2010, 09:34:52 PM »

Nixon's the one.



klc
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K1JJ
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« Reply #63 on: November 23, 2010, 10:40:38 PM »

"I really can't agree with that statement, even with the sly smilie. "


If you knew me better you'd find you're preaching to the choir... Grin


T

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« Reply #64 on: November 24, 2010, 05:46:26 AM »

A test method is provided. Measure the average power of one cycle of RF at the peak of the modulation envelope. Pretty simple, most certainly far more simple than the arcance mil-specs.

I requested the FCC provide a test method and a time constant on PEP when they came up with this crazy method. They never responded. In the Mil world a test method is provided.
I think the FCC gave up trying to measure PEP. There is nothing out there that is affordable for a Ham to own that meaures PEP. That's the kicker for this PEP mess. Adjust your TX for whatever power makes you smile and schwang the monkey. Remember that higher power will start stresing antenna parts and tuners and PL259's,,,,,,,,this is getting closer to 2.5kw outpoot. heeee heeee Has anyone read any FCC arrests for excessive PEP?,,,,,,,,,
FRED
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« Reply #65 on: November 24, 2010, 02:40:35 PM »

Has anyone read any FCC arrests for excessive PEP?,,,,,,,,,
FRED

Nope! I haven't seen one for the amateur service in recent years. Most enforcement actions regarding power levels in the last year seem to be for 11 meter infractions, and run something like this:

  "It has come to the attention of the Federal Communications Commission that
   at various times in the last several months you have operated overpowered
   transmitting equipment on 11 meters that has interfered with communications in
   the 10 meter band, for which a license is required."

or...

  "The general rule is that consumer electronics are protected only by
   manufacturer design from receiving any unwanted radio signals
   and home electronics have no priority over any radio or broadcast
   service. Nevertheless, if a CB operator is operating at excessive power
   levels, it is the responsibility of the CB operator to correct the
   problem."

It's always interesting to browse the "Warning Letters" section.

http://www.fcc.gov/eb/AmateurActions/Welcome.html

Incidentally, I do love the wording used by the FCC when they respond to consumer complaints about interference to their toasters and other such important appliances:

  "...consumer electronics are protected only by manufacturer
   design from receiving any unwanted radio signals and home
   electronics have no priority over any radio or broadcast
   service."

I sure wish that kind of language was thrown around 30 years ago when I had a nasty complaint about TVI (neighbor 500 feet away with a Radio Shack mast mount preamp) and one for telephone RFI (neighbor 1000 feet away with a horrific self-installed phone-intercom system). It seems like we were pretty much on our own back then to sort that crap out.
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« Reply #66 on: November 27, 2010, 10:15:38 PM »

Funny thing ... the CB regs talk about AM carrier output at 4W.

And besides, isn't there something about meter inaccuracies from where the meter is located on a length of coax? IMHO Feces is just giving us a guideline and really do not intend the compliance be one of accurate measurement. They are implying just don't run 5kW when 1.5kW will do. The FCC just doesn't care until they get complaints, and even then it's only complaints from other services that are important to them at a given moment in time.

325W carrier 100% mod is fine for most. Is it 1500W PEP ... yup. But who cares. Apparently nobody. Take it from me. Worry about your antenna and radiated power. I've run 450W carrier 100% mod and I haven't strapped anybody.  "50W Fred" straps me! Grin

John, W2WDX
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k4kyv
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« Reply #67 on: November 28, 2010, 01:07:41 PM »

And besides, isn't there something about meter inaccuracies from where the meter is located on a length of coax?

I recall at a hamfest FCC forum shortly after the power output rule went into effect, someone asked that very same question. The moderator  responded something to the effect that for the purposes of power output measurement,  the FeeCee inspector would place the meter at the "output terminals" of the transmitter.

Now, that might be clearly defined and unambiguous for the typical appliance operator working his ricebox or leenyar directly into the coax feedline of his G5RV.  But what if he is using a tuner; is the "output terminal" defined as the SO-239 on the transmitter or amplifier, the output terminals of a transmatch, or if he is using open wire feeders, the ceramic terminals on the tuner where the "ladder line" is attached?

In the case of homebrew transmitters, it could be a whole different story. It is the operator who designed and built the transmitter who defines exactly what constitutes the "output terminals".  If one decides to construct a rig so that part of the output tank circuitry is located remotely from the rest of the transmitter and coupled via a link of coax, twisted pair or parallel-wire transmission line, then the "output terminals" could be the ones located on the wall of the "dawg house", feeding the transmission line that leads directly to the antenna.

This is particularly true with solid state rigs that have untuned outputs. With hollow-state transmitters, the tank circuit is an impedance matching network, usually a link-coupled, PI or PI-L network, contained in the cabinet as an integral part of the transmitter. With to-day's solid state designs, the tank circuit is no longer included in the transmitter cabinet but is sold as a separate unit and called a "transmatch", which the owner must pay extra bux for. The rig will work without the transmatch if and only if the load is close to purely resistive 50 ohms.  As soon as anything more than a slight mismatch occurs as indicated by a SWR that is a little higher than 1:1, the transmatch is needed to allow the rig to deliver full power into the load.  In other words, a tank circuit is still required after all, but it is now sold as an "extra" or "accessory".

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Don, K4KYV                                       AMI#5
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« Reply #68 on: November 28, 2010, 02:29:27 PM »

That brings up a good point. The transmitter ends at the point where the antenna is connected. It is reasonable to push 1800W peaks into a tuner when the match is so difficult that only 1500 comes out. There are reasons why antenna tuners are large enough to dissipate heat. Consider those 'wideband' folded dipoles with the 600 Ohms termination in the center. The power converted to heat in the termination should be subtracted from the TX output because it is not being radiated. Nonetheless Uncle Charlie is going spot the largest cabinet in the room and ask where the coax connector is. That is just how things are. Those running QRO could make use of a T pad before the PA for special occasions.
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« Reply #69 on: November 28, 2010, 05:34:41 PM »

From what I understand, a high profile generated, sneak QRO visit from Charlie might work something like this...

They park down the street and take a field strength measurement while you're on the air. They stop by (with another car) and axe you to load up the rig. It doesn't matter what power you load up as long as they can measure it with their wattmeter and take an identical field strength reading down the street.

Let's say you load up to a measured 1500w out for them. If the previous field strength reading was 3db louder, you're busted... Grin


Assuming you were previously using a horizontal antenna, the way around this would be to switch on a vertical antenna the second time, giving a stronger local groundwave signal - providing a much stronger field strength reading. This would make your 2nd test pass easily. Something akin to faking a urine drug test, I suppose.

I've never heard of this type of visit actually being done in practice, but seems like a viable method if their motivation was high due to high profile jamming complaints, etc..

T
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« Reply #70 on: November 28, 2010, 07:26:52 PM »

Uncle Charlie is going spot the largest cabinet in the room and ask where the coax connector is. That is just how things are.

Then you show him there is no coax connector.  Just a ceramic feed-through with a bare wire attached.  Grin

Roger, N4IBF (SK) was paid a visit after a guy down the road had persistently complained about RFI to his AM broadcast radio, keeping him from listening to the baseball game. The inspector measured the power output from Roger's BC-610.  The only measuring instrument he had with him was a Bird 43.
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Don, K4KYV                                       AMI#5
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« Reply #71 on: November 28, 2010, 09:14:51 PM »

Don said:
Quote
Roger, N4IBF (SK) was paid a visit after a guy down the road had persistently complained about RFI to his AM broadcast radio, keeping him from listening to the baseball game. The inspector measured the power output from Roger's BC-610.  The only measuring instrument he had with him was a Bird 43.


See, all they care about is 'dem Bird Watts'.  Wink
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« Reply #72 on: November 28, 2010, 09:26:59 PM »

 "  See, all they care about is 'dem Bird Watts'.  Wink  "


Thats cause the Bird watts are the best watts there is...  havent you heard that the Bird is the word?



klc


.--. .- .--. .-   --- --- --  .-  -- --- .--   -- --- .--
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« Reply #73 on: November 28, 2010, 09:35:06 PM »

BAH-BAH-BAH-BAH-BAH-BAH-BAH-
BAH-BAH Omma Maw Maw Bah Bah Omma Maw Maw


http://www.youtube.com/watch?v=9QypTBjlFCM
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« Reply #74 on: November 28, 2010, 09:37:24 PM »

"  See, all they care about is 'dem Bird Watts'.  Wink  "


Thats casuse the Bird watts are the best watts there is...  havent you heard that the Bird is the word?



klc


.--. .- .--. .-   --- --- --  .-  -- --- .--   -- --- .--

Poppa eeew maux maux
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