[CW] Charts of Radio Morse and American Wire Morse.

[Donald Chester via CW]

>BTW, if this is the fellow who created the power limit rule for AM he is
just out of it. 
>Richard Knoppow WB6KBL

Yes, that's the guy.


>There is no special power limit rule for amplitude modulation (AM) or
double sideband amplitude >modulated full carrier.

>The power level for all modes is 1500 watts peak envelope power output.

>The problem - to the AM'ers - is that the old definition of power limit was
1,000 watts input.  >When AM double side band full carrier was run it would
be 4,000 watts peak envelope power input and >the output would be higher
than the new definition of maximum power allowed of 1500 watts PEP.  It
>would be something around 2,500 watts PEP if the AM operators ran their old
1,000 watt input >carrier with 100% modulation and this would be twice the
power permitted.

>David N1EA


That's the party line according to Johnston. But in reality every other mode
enjoyed a power increase, but (legal) AM power was reduced in half. After
many years of trying and not succeeding, Johnston finally was able to land a
substantial a blow to AM, even though he couldn't pull off eliminating it
from the amateur bands. From the earliest days of radio, the amateur power
limit for AM was 1000 watts input. Then the rules changed; your "Maserati"
that you once could legally floor is now stuck in third gear if one is to
obey by the letter of the rules. That hindered the maximum output of AMers.
Not to condone illegal amateur radio activity, but if the rules are changed
on you in mid-stream to your disadvantage, how much respect will you tend to
have for them?


>The reason it was changed was to give amateur operators more power
authorization.  

Not according to the FCC rulemaking docket. The FCC's stated justification
was that poking round inside the high voltage circuitry of an unfamiliar
transmitter to measure DC voltage and current, posed a safety hazard to FCC
field personnel. One FCC official stated in an interview in CQ Magazine that
they wanted to change the old DC input rule to output power because it was
"antiquated" - "not so much a problem but more an embarrassment to the
Commission".

In the original NPRM the FCC claimed their intent was "to improve the method
of measuring transmitter power, not to change the actual power level
amateurs use". But then they went on to claim that structuring the new power
limit in such a way as to preserve historic AM power would make the wording
of the rule too cumbersome.

Shortly after the US adopted  the output power standard, Canada followed
suit. The section that defines the Canadian power limits reads as follows:
 
"(b) where expressed as radio-frequency output power measured across an
impedance matched load,
(i) 2,200 W peak envelope power for transmitters that produce __any__ type
of single sideband transmission, or
(ii) 750 W carrier power for transmitters that produce any other type of
emission."

Canadians must be more intelligent than United States-ese. They have a power
limit rule that makes a distinction between SSB type modes and AM type
modes, yet is short, simple and concise.  The FCC stated in their Report and
Order that they adopted the rule as it is, because they couldn't figure out
how to do that.

>Years ago the cost of R.F. Output PEP measuring devices was quite
expensive, now they're much more >reasonable and in fact most hams have such
a device.

The FCC rejected the idea of an__ average __ power output limit, purportedly
because measuring average, or mean, output power is more complex than
reading peak power. Actually,  basing the measuring instrument on a
thermocouple RF ammeter  would have been simple and low-cost. A typical
Hammy Hambone RF "wattmeter" does not measure power at all; it's a simple RF
voltmeter whose scale is calibrated in power in watts, on the assumption
that the transmitter is working into a perfectly matched 50-ohm non-reactive
load. A "watt" meter could just as easily consist of an RF ammeter with a
scale calibrated in watts output into a 50-ohm non-reactive load. A
thermocouple meter is a true RMS-reading instrument. "Average" or "mean"
power is calculated via Ohm's law, based on RMS voltage and RMS current. The
"average" power reading on a meter like the Bird 43 bases its reading on
"average" RF voltage.  Here is where the rub comes in. Please note that (1)
average power = RMS voltage X RMS current,  NOT average voltage X average
current.  (2)There is no such a thing as "RMS power" or "RMS watts" even
though you often see the term misused in connection with commercial
products.

A true average-reading wattmeter is now commercially available, the Bird
APM-16. See
http://www.birdrf.com/Products/Wattmeters_Line%20Sections/PortableWattmeters
/APM-16_Average-Reading-Power-Meter.aspx 

Johnston appeared obsessed with P.E.P. and had been pushing for some kind of
power limit based on P.E.P. since the 1970s. Originally, in a
"Restructuring" docket that was never adopted, they proposed 2000 watts
P.E.P. output. Then, in another proposed re-write of the rules, they
suggested a "temporary" limit based on P.E.P. INPUT, until a "better
solution" could be arrived at.

Don k4kyv 





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