On 8/1/2014 8:45 AM, rickman wrote:
On 8/1/2014 8:00 AM, Jerry Stuckle wrote:
On 8/1/2014 12:37 AM, rickman wrote:
On 7/31/2014 9:47 PM, Jerry Stuckle wrote:
On 7/31/2014 9:29 PM, rickman wrote:
On 7/30/2014 9:40 AM, Jerry Stuckle wrote:
On 7/30/2014 1:22 AM, Lostgallifreyan wrote:
Jerry Stuckle wrote in
news:lr9ohj$33f$1@dont-
email.me:

But the amplifier you're trying to use is meant to feed a receiver
directly, not another antenna. So output is going to be very
low (on
the order of microwatts) - much lower than any amplifier which
feeds an
antenna.


Small point, but.... Microwatts. Those new legal microstransmitters
are said
to be in NANOwatt range output, but allegedly work on the distance
scales I'm
interested in. Microwatts should certainly have worked, but despite
the crude
test dipole being good (on standard wired reception test anyway), it
didn't
work for transmitting even a foot or two with the radio's whip
parallel to
the upper part of it. If nanowatts should have, the MAR-6 looks like
driving
picowatts, if I'm lucky.


I would suggest you check again. Receivers aren't that sensitive.
Most
unlicensed transmitters are in the 100-500 mw range, and have a
coverage
of maybe 100 feet. And picowatts aren't even worth discussing.

I'm unclear, is mW microwatts or milliwatts as you wrote it? The
reason
I ask is that a 500 milliwatt transmitter would certainly have a
receivable distance much greater than 100 feet, no?


According to standards, mW is milliwatts. uW (actually, greek "mu"W
but
I'm not using a charset here that defines it, so the standard is "uW")
would be microwatts.

I'm not asking about the standard, I'm asking what you meant by mW. Why
do you say with a power level of 500 mW (27 dBm) a transmitter would
only have a range of 100 feet? With the low bandwidth we are discussing
this seems to be *very* short.


I follow the standards.

Not much more than that. Remember - the commercial FM band has +/-
75kHZ deviation. Additionally, there are limits as to the antenna on
Part 15 devices - you can't, for instance, place a 6db gain antenna 200'
in the air.

Realtors around here use them to advertise houses; they place one in the
house with a recording that describes the house with a sign out front
showing the frequency. Reception from the street is typically within a
couple of houses either side.

Our college radio station ran 10 watts to a 3db gain antenna on top of
one of the dorms. The dorm was only 3 stories plus attic, so the
antenna was maybe 40-45 feet in the air. Good coverage was about a 2-3
mile radius with a typical portable receiver (or car); an external
antenna on the receiver obviously extended that.

Ok, if you are talking about 500 milliWatts, how do you get 100 feet
from that?


Portable receivers have notoriously poor antennas and receive
sensitivity. A whip antenna is better, but awkward. An external
antenna on a good receiver will receive a fair amount further - but
that's not portable. Plus building, etc. will attenuate the signal
(concrete is really bad - add steel rebar and it's even worse).

Like anything else - you *can* get farther than 100 feet, but that's
about all you can expect reliably.

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