[AMRadio] AM Amps


Geoff w5omr at w5omr.shacknet.nu
Sat Mar 26 11:52:52 EST 2005


Donald Chester wrote:

>> From: "Robert M. Bratcher Jr." <bratcher at pdq.net>
>
>> I wonder how many AM'ers run more than the legal 375 watts? I've 
>> thought about it...
>
>
> Check out the regs in Part 97.  There is no mention whatever of 375 
> watts.


Don is right.
The legal maximum amount of power *ANY* Amatuer Radio Operator can run, is
1,500 watts, Peak Envelope Power, regardless of mode.

Personally, I still say that there should be some experimenting done on 
75m with Narrow-Band
Frequency Modulation.  In fact, somewhere in Part 97, there is a line 
that says (paraphrased)
"FM can be run on HF, as long as it's no wider than a conventional AM 
signal."

Some people (Jim/WD5JKO springs to immediate mind) have experienced with 
"Sliver-Band"
FM on 40m, wedging inbetween a couple of AM Broadcast stations on 7.155 
and 7.160Mc, if
memory serves correct.

The point is, if 1500W pep is the MAX, then why -not- run FM w/2.5kc of 
deviation, as long
as it's legal?

Excite the big rig with a modern day rice-box on FM, check the deviation 
levels, adjust to 5kc
and load 'er up!

I've heard phase distortion on FM before (10m) that accompanies QSB and 
as far as I'm concerned,
there's not much difference between phase distortion, and selective 
fade.  Bottom line in both is,
the signal is unreadable, but when it's strong, "full quieting" takes on 
a different effect, if operating on
FM (or Phase modulation, for that matter, ala Central Electronics Lab 
xmtrs).

The reason some people (incorrectly) think that there's a 375w limit on 
AM now (since we had the
old "1kW DC Input to the final" law repealed in 1991) is that 375w, at 
100% modulation with a sine
wave equals 1,500w PEP output.  That's absolutely ridiculous, though... 
who (does anyone know?)
talks in pure sine waves?

We've been down this road before, and we'll probably go down this road, 
again... but for those who
don't know, there's been a lot of math, and discussion done in this 
realm, and the results can be found at
h ttp://w5omr.shacknet.nu/~wa5bxo/asyam/Amplitude%20Modulation.htm
(I mirrored the information here, because qsl.net is so slow, these 
days.  Cut 'n' paste the link to your
browser, and remove the space between 'h' and 'ttp:/'  ... thrwarting 
off web-crawlers and spying robots)

73 = Best Regards,
-Geoff/W5OMR





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