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.

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.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

Jerry Stuckle wrote in news:lraskh$gup$1@dont-
email.me:

Most
unlicensed transmitters are in the 100-500 mw range, and have a coverage
of maybe 100 feet.

That sounds right. I thought nanowatts seemed a bit small a claim. I probably
need about 10mW based on what you said there. (I think it was Wikipedia's
article that stated the nanowatts, but as so often happens, there was no
mention of the antenna and actual radiated power, no hint of what efficiency
(or lack of) resulted.

I won't retry for now. Messing around with a direct wired link to the
external aerial is more fun for a while. ETM on a PL-390 is as fun as many
people have said it is...


And picowatts aren't even worth discussing.


I should never have mentioned them.

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?

--

Rick

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.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

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.

--

Rick

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.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

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?

--

Rick

On Thu, 31 Jul 2014 21:29:11 -0400, rickman wrote:

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?

He's right. The receivers aren't that sensitive. For example, I just
excavated the Silicon Labs Si470-31 data sheet, which shows an FM
sensitivity of 1.1 uV into 50 ohms for a S+N/N ratio of 26dB. The
reason is the wide (200KHz for FM and 500KHz HD Radio) occupied
bandwidths. The bigger the bandwidth, the more noise gets in, and the
lower the sensitivity. Crudely, double the bandwidth and lose -3dB
(i.e. half) in sensitivity.

Much depends on the antennas and the field strength sensitivity. Let's
see what the Friis Equations produces. If I assume a best case of a
2dB gain dipole at the transmitter, but a crude earphone cord antenna
at the receiver (-3dB at best). Then what I get is:
TX 27dBm (500 mw)
TX ant 2dB
path loss ????
RX ant -3dB
RX sens -107dBm
Path Loss = 27 + 2 -3 -107 = 81 dB
Plugging into:
http://www.proxim.com/products/knowledge-center/calculations/calculations-free-space-loss
I get 1.7 miles at 100 MHz. Looks like it should work.

Things get messy when I run the numbers again with the typical
receiver sensitivity found in analog receivers. These have typical
sensitivity of 9 dBf. That's dB(Femtowatts) or 10^-15 watts
reference. Converting to a milliwatts reference, that's:
9*10^-15 watts / 1*10^-3 watts = 9*10^-12
converting to dB, or 10 log of the ratio:
dB = 10*log(9*10^-12) = 10 * (-11) = -110 dBm
which is allegedly 3dB more sensitive than the all digital chip. I
don't believe it. So, with 3dB less sensitivity, you should get about
half the range or 0.85 miles.




--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...

On Thu, 31 Jul 2014 21:29:11 -0400, rickman wrote:

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?

He's right. The receivers aren't that sensitive. For example, I just
excavated the Silicon Labs Si470-31 data sheet, which shows an FM
sensitivity of 1.1 uV into 50 ohms for a S+N/N ratio of 26dB. The
reason is the wide (200KHz for FM and 500KHz HD Radio) occupied
bandwidths. The bigger the bandwidth, the more noise gets in, and the
lower the sensitivity. Crudely, double the bandwidth and lose -3dB
(i.e. half) in sensitivity.

Much depends on the antennas and the field strength sensitivity. Let's
see what the Friis Equations produces. If I assume a best case of a
2dB gain dipole at the transmitter, but a crude earphone cord antenna
at the receiver (-3dB at best). Then what I get is:
TX 27dBm (500 mw)
TX ant 2dB
path loss ????
RX ant -3dB
RX sens -107dBm
Path Loss = 27 + 2 -3 -107 = 81 dB
Plugging into:
http://www.proxim.com/products/knowledge-center/calculations/calculations-free-space-loss
I get 1.7 miles at 100 MHz. Looks like it should work.

Things get messy when I run the numbers again with the typical
receiver sensitivity found in analog receivers. These have typical
sensitivity of 9 dBf. That's dB(Femtowatts) or 10^-15 watts
reference. Converting to a milliwatts reference, that's:
9*10^-15 watts / 1*10^-3 watts = 9*10^-12
converting to dB, or 10 log of the ratio:
dB = 10*log(9*10^-12) = 10 * (-11) = -110 dBm
which is allegedly 3dB more sensitive than the all digital chip. I
don't believe it. So, with 3dB less sensitivity, you should get about
half the range or 0.85 miles.
================================================== =====

When I was in the Navy, I was detached from my ship for a short school. I
bought a Radio Shack FM broadcaster that used a 9v battery. A couple of
guys and I fashioned a folded dipole for the FM band as the transmit antenna
and used a BCB radio for the audio input. We pushed the folded dipole a few
feet out a second-story window on a broom handle and proceeded across the
base to see how far we could hear our signal on a portable FM radio.

We went about a 1000 feet before the signal became useless, although there
were some dropouts closer than that. I do not know the output of the device
in milliWatts, but I suspect it is much less than the nominal 100 milliWatts
that limits the no-license operation.

"Sal"