> I found this page on a website interesting because he talks
> about the different fm transmitters and part 15 compliance.
>
http://global-cm.net/distribu.html
>
I don't know who wrote the text on that URL (partial clip below), but they are WAY off the mark as far as what Part 15 allows for systems in the FM broadcast band.
Part 15 does NOT allow a "100 mW maximum limit" for Part 15 FM systems. That is a Part 15
AM Rule.
A radiated power of only ~11.4 nanowatts is needed to generate the maximum legal Part 15 FM field from a simple 1/2-wave dipole. Ramsey, EDM and the "Pico" units all are rated for _far_ more power than necessary for legal Part 15 FM operation at the maximum legal field strengths.
+ + +
PARTIAL CLIP from global-cm.net
"RF output level of about dBmV translates to just under
100 microwatts of power. This is about 20 dB less than that found
on the typical Ramsey FM 10, which is close to the legal power limit
in the United States, under 10 milliwatts ( dBmV). Adding an
amplifier to match the ballpark legal limit of 100 milliwatts
( dBmV) is somewhat difficult for the layman to calculate. It is
correctly described as 250 microvolts received on a 1-meter dipole
antenna, distance at 3 meters from transmitting antenna. A very
efficient antenna when connected to the Ramsey units can actually
put you over the legal limit. Their FM-25 unit when set to the
"export" output position and coupled to ANY antenna will exceed
the FCC limits. Do at your own risk, but be well aware of the pen-
alties, should you be so unfortunate as to be made an enforcement
example.
How to get the PCFM up to near the legal power level? The cheap
and "dirty" way would be to connect an inexpensive VHF distribution
amplifier to the output of the PCFM, and then to an antenna system.
The PICO TA-25 will get you within 5 dB of the 100 mW maximum limit.
Just over dBmV is a pretty respectable power level, if you are
on a restricted budget."
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