Brenda Ann wrote:
"John - KD5YI" wrote in message
. . .

My guess is 3 mW.

John

The level is the same as emissions within the CB band:


Sec. 15.227 Operation within the band 26.96-27.28 MHz.

(a) The field strength of any emission within this band shall not exceed
10,000 microvolts/meter at 3 meters. The emission limit in this paragraph is
based on measurement instrumentation employing an average detector. The
provisions in Sec. 15.35 for limiting peak emissions apply.
. . .

The amount of power applied to an isotropic radiator which will generate
10,000 uV/m at 3 meters is 30 microwatts. This assumes that the 3 meter
distance is in the far field, or that it's measured in the far field and
extrapolated to 3 meters as though 3 meters were in the far field, which
is the method and assumption used by the FCC.

A simple dipole reduces the permissible power to about 23 uW, and ground
reflections will typically nearly double the field strength, so a safe
power level would be about 6 microwatts into a dipole antenna over
ground for someone interested in conforming to the regulations.

Roy Lewallen, W7EL

Roy Lewallen wrote:
Brenda Ann wrote:

"John - KD5YI" wrote in message

. . .


My guess is 3 mW.

John


The level is the same as emissions within the CB band:


Sec. 15.227 Operation within the band 26.96-27.28 MHz.

(a) The field strength of any emission within this band shall not
exceed 10,000 microvolts/meter at 3 meters. The emission limit in this
paragraph is based on measurement instrumentation employing an average
detector. The provisions in Sec. 15.35 for limiting peak emissions apply.
. . .


The amount of power applied to an isotropic radiator which will generate
10,000 uV/m at 3 meters is 30 microwatts. This assumes that the 3 meter
distance is in the far field, or that it's measured in the far field and
extrapolated to 3 meters as though 3 meters were in the far field, which
is the method and assumption used by the FCC.

A simple dipole reduces the permissible power to about 23 uW, and ground
reflections will typically nearly double the field strength, so a safe
power level would be about 6 microwatts into a dipole antenna over
ground for someone interested in conforming to the regulations.

Roy Lewallen, W7EL


Hey, Roy -

My 3 mW answer was for 30 meters. I think that ratios correctly to your 30
microwatts at 3 meters. Yes?

John

John - KD5YI wrote:

Hey, Roy -

My 3 mW answer was for 30 meters. I think that ratios correctly to your
30 microwatts at 3 meters. Yes?

Yep, that's right. And I finally got curious enough to look up the
actual regulation. According to section 15.225(a), intentional radiators
at 13.553-13.567 MHz are allowed 15,848 uV/m at 30 meters, which is
about 4.75 mW to an isotropic antenna in free space. There's also a
0.01% frequency stability requirement which would imply crystal control.
And any emissions extending outside the band have to be about 54 dB
lower, 30 uV/m at 30 m.

Roy Lewallen, W7EL

Roy Lewallen wrote in
:

John - KD5YI wrote:

Hey, Roy -

My 3 mW answer was for 30 meters. I think that ratios correctly to your
30 microwatts at 3 meters. Yes?

Yep, that's right. And I finally got curious enough to look up the
actual regulation. According to section 15.225(a), intentional radiators
at 13.553-13.567 MHz are allowed 15,848 uV/m at 30 meters, which is
about 4.75 mW to an isotropic antenna in free space. There's also a
0.01% frequency stability requirement which would imply crystal control.
And any emissions extending outside the band have to be about 54 dB
lower, 30 uV/m at 30 m.

Roy Lewallen, W7EL



So if N9OGL's transmitions are legal power wise, he would basically be
broadcasting for the kids across the street. Maybe he could take song
requests. They can just shout out their front doors what songs they want
him to play.

SC

So if N9OGL's transmitions are legal power wise, he would basically be
broadcasting for the kids across the street. Maybe he could take song
requests. They can just shout out their front doors what songs they want
him to play.

SC

I can copy perhaps 8 beacons on 13.555 MHz from all across the U.S.
Assuming they too are running the power level Roy calculated, N9OGL's beacon
should also be copyable.

Dale W4OP

"Dale Parfitt" wrote in
news:R0aCg.15333$l95.9940@trnddc08:



So if N9OGL's transmitions are legal power wise, he would basically be
broadcasting for the kids across the street. Maybe he could take song
requests. They can just shout out their front doors what songs they
want him to play.

SC

I can copy perhaps 8 beacons on 13.555 MHz from all across the U.S.
Assuming they too are running the power level Roy calculated, N9OGL's
beacon should also be copyable.

Dale W4OP


You don't need to tell me the strengths of CW. I'm a CW advocate.
Just listen to the NCDXF beacons on 14.100. You can easily hear the 100mW
tone all over the world when there is propagation with a simple antenna.
I'm just saying the RF Todd is puting into his antenna has to be quit low
if he is transmitting legal power wise.

Sc

Slow Code wrote:
Roy Lewallen wrote in
:



So if N9OGL's transmitions are legal power wise, he would basically be
broadcasting for the kids across the street. Maybe he could take song
requests. They can just shout out their front doors what songs they want
him to play.

SC

Not true.
I have an AM "beacon" running some test groups smack dab
in the middle of the HiFer/ISM 22M allocation. At maximum power
I am at the legal limit. Most of my tests are -20dB from that level and
I
have copied my "becaon" from over 100 miles away twice. I was -6dB
down from max, and was rather shocked. Don't rule out the odd fluke
path.

If you ever hear a YL reading a set of word pairs each followed by
a ID nubmber in cut morse, that is my odd little station.

I normally keep the power -63dB down from max legal, and only boast
it while actually conducting tests.

Terry in central KY

wrote in message
oups.com...

Slow Code wrote:
Roy Lewallen wrote in
:



So if N9OGL's transmitions are legal power wise, he would basically be
broadcasting for the kids across the street. Maybe he could take song
requests. They can just shout out their front doors what songs they want
him to play.

SC

Not true.
I have an AM "beacon" running some test groups smack dab
in the middle of the HiFer/ISM 22M allocation. At maximum power
I am at the legal limit. Most of my tests are -20dB from that level and
I
have copied my "becaon" from over 100 miles away twice. I was -6dB
down from max, and was rather shocked. Don't rule out the odd fluke
path.

If you ever hear a YL reading a set of word pairs each followed by
a ID nubmber in cut morse, that is my odd little station.

I normally keep the power -63dB down from max legal, and only boast
it while actually conducting tests.

Terry in central KY

Give me the exact frequency Terry.

Dale W4OP

Roy Lewallen wrote:
John - KD5YI wrote:

Hey, Roy -

My 3 mW answer was for 30 meters. I think that ratios correctly to your
30 microwatts at 3 meters. Yes?

Yep, that's right. And I finally got curious enough to look up the
actual regulation. According to section 15.225(a), intentional radiators
at 13.553-13.567 MHz are allowed 15,848 uV/m at 30 meters, which is
about 4.75 mW to an isotropic antenna in free space. There's also a
0.01% frequency stability requirement which would imply crystal control.
And any emissions extending outside the band have to be about 54 dB
lower, 30 uV/m at 30 m.

Roy Lewallen, W7EL

Do what??? The power output can vary depending on a number of things
including coax and antenna, you can run 1,000 watts and come up 10,000
uV/meter at a distance of 30 meters. As the FCC Office of Engineering
and Technology has stated in their bulletin which deals with Part 15.

"What is the relationship between "microvolts per meter" and Watts?
Watts are the units used to describe the amount of power generated
by a transmitter. Microvolts per meter (µV/m) are the units used to
describe the strength of an electric field created by the operation of
a transmitter. A particular transmitter that generates a constant level
of power (Watts) can produce electric fields of different strengths
(µV/m) depending on, among other things, the type of transmission line
and antenna connected to it. Because it is the electric field that
causes interference to authorized radio communications, and since a
particular electric field strength does not directly correspond to a
particular level of transmitter power, most of the Part 15 emission
limits are specified in field strength."

Todd N9OGL
OMEGA ONE BROADCASTING

N9OGL wrote:
Roy Lewallen wrote:

John - KD5YI wrote:

Hey, Roy -

My 3 mW answer was for 30 meters. I think that ratios correctly to your
30 microwatts at 3 meters. Yes?

Yep, that's right. And I finally got curious enough to look up the
actual regulation. According to section 15.225(a), intentional radiators
at 13.553-13.567 MHz are allowed 15,848 uV/m at 30 meters, which is
about 4.75 mW to an isotropic antenna in free space. There's also a
0.01% frequency stability requirement which would imply crystal control.
And any emissions extending outside the band have to be about 54 dB
lower, 30 uV/m at 30 m.

Roy Lewallen, W7EL


Do what??? The power output can vary depending on a number of things
including coax and antenna, you can run 1,000 watts and come up 10,000
uV/meter at a distance of 30 meters. As the FCC Office of Engineering
and Technology has stated in their bulletin which deals with Part 15.

"What is the relationship between "microvolts per meter" and Watts?
Watts are the units used to describe the amount of power generated
by a transmitter. Microvolts per meter (µV/m) are the units used to
describe the strength of an electric field created by the operation of
a transmitter. A particular transmitter that generates a constant level
of power (Watts) can produce electric fields of different strengths
(µV/m) depending on, among other things, the type of transmission line
and antenna connected to it. Because it is the electric field that
causes interference to authorized radio communications, and since a
particular electric field strength does not directly correspond to a
particular level of transmitter power, most of the Part 15 emission
limits are specified in field strength."

Todd N9OGL
OMEGA ONE BROADCASTING




C'mon, Todd. He qualified it by saying "4.75 mW to an isotropic antenna in
free space." It is just a way to get a "feel" for how much power might be
required based on the FCC uV/m limit under certain theoretical conditions.

I would start with a calculation like this if I were designing a transmitter
whose signal has to meet those limits. I think that would be better than
starting with a 1000W transmitter when only a few milliwatts is required.

When was the last time you used an isotropic antenna? How was your trip to
free space?

John