"Michael Coslo" wrote in message
...
Cecil Moore wrote:
Michael Coslo wrote:
People have been sending tiny amounts of RF up their antennas to find
out things about it since before Methuselah, ...

Mike, do you really think the Nephilim were people?

I guess it depned on whther you thing they were descended from the
begatten of Seth and Cain or the Anakim.

I wonder if they used an antenna analyzer on the Ark??

Nope the Doves had Radar (;-)
Lamont

Bob Miller wrote:

I have an Oak Hills Research WM-2 QRP Wattmeter, which includes a
0-100 milliwatt scale.

With an MFJ 269 Antenna Analyzer hooked to the transmitter side of the
wattmeter, and an MFJ dummy load hooked to the load side of the
wattmeter, I get a reading of 3 milliwatts forward, 0 milliwatts
reflected.

Not sure whether the FCC is concerned with signals at the 3 milliwatt
level...

Most if not all the part 15 rules are defined in terms of field
strength, not power. 3 mW is way, way more than enough to exceed some of
the limits on some frequencies, when connected to even a poor antenna.
For example, Part 15 shows, in 15.209, that intentional radiators aren't
allowed to produce a field strength greater than 100 uV/m (with
exceptions) at 3 meters from 30 - 88 Mhz. 3 milliwatts will produce
*1,000 times*, or 60 dB greater than, this amount when connected to an
isotropic antenna. Hook it to a dipole to get another few dB. The limit
for class A digital devices (one class of unintentional radiators) is
the same in that range, according to 15.109. So don't think that just
because you consider a signal to be QRP that it's legal.

That said, I agree that chances of prosecution are zero for using these
devices unless serious and/or intentional interference results. And I
strongly agree with the folks who have said that the last thing you want
to do is force a specific ruling on the matter from the FCC.

Roy Lewallen, W7EL

Roy Lewallen wrote in news:13cv2n6r7q05s78
@corp.supernews.com:

....
Most if not all the part 15 rules are defined in terms of field
strength, not power. 3 mW is way, way more than enough to exceed some
of
the limits on some frequencies, when connected to even a poor antenna.

I wrote a little article to inform people in the BPL debate... it started
out as:

How much radiated power does it take to create an S9 signal?

Try this quick quiz:

What is the EIRP of a 7MHz transmitter that results in a S9 signal at a
receiver located 1km from the transmitter, is it closest to:

1. 5 Watts;
2. 1 Watt;
3. 300 milliWatts;
4. 5 milliWatts;
5. 3 microWatts.

Answer: e, it is just 3 microWatts EIRP.

Remember that it takes less than a nanoWatt EIRP (ie 10E-9 Watts, a
thousandth of a millionth of a Watt) of leakage of radiofrequency energy
at 7MHz from BPL enabled power lines 10 metres from a dipole to cause S9
level interference.

Are you ready for BPL enablement of your home and neighbourhood?
http://www.vk1od.net/bpl/AreYouReady.htm

Owen

Michael Coslo wrote:
You been out of town? I haven't heard much from you lately.

I have moved to a new QTH and only had dialup for
awhile - hardly worth the effort of dialing.
--
73, Cecil http://www.w5dxp.com

I have moved to a new QTH and only had dialup for
awhile - hardly worth the effort of dialing.
--
73, Cecil http://www.w5dxp.com
===================================
Cecil , Great antenna web site . Intent to implement your 'no tuner'
dipole with 450 ohms feeder by adding bits of feeder operated by relays
with quadruple change over contacts.
I assume it is alright to build the lot in a box made of MDF with the
450 Ohms ribbon coiled up.
An open perspex sheet would be somewhat difficult to accommodate in my
shack.

Frank GM0CSZ / KN6WH north of Scotland

Highland Ham wrote:
Cecil , Great antenna web site . Intent to implement your 'no tuner' dipole with 450 ohms feeder by adding bits of feeder operated by relays with quadruple change over contacts.
I assume it is alright to build the lot in a box made of MDF with the 450 Ohms ribbon coiled up.
An open perspex sheet would be somewhat difficult to accommodate in my shack.

The only way to coil up 450 ohm line is to keep all
parts of each coil at least 3-4 inches from all other
coils. A spiral will work but you certainly *cannot*
successfully coil up balanced ladder-line as you
can with unbalanced coax.
--
73, Cecil http://www.w5dxp.com

On Sat, 25 Aug 2007 08:31:08 -0500, Bob Miller wrote:

On Fri, 24 Aug 2007 18:50:30 -0700, Roy Lewallen
wrote:

Bob Miller wrote:

I have an Oak Hills Research WM-2 QRP Wattmeter, which includes a
0-100 milliwatt scale.

With an MFJ 269 Antenna Analyzer hooked to the transmitter side of the
wattmeter, and an MFJ dummy load hooked to the load side of the
wattmeter, I get a reading of 3 milliwatts forward, 0 milliwatts
reflected.

Not sure whether the FCC is concerned with signals at the 3 milliwatt
level...

Most if not all the part 15 rules are defined in terms of field
strength, not power. 3 mW is way, way more than enough to exceed some of
the limits on some frequencies, when connected to even a poor antenna.
For example, Part 15 shows, in 15.209, that intentional radiators aren't
allowed to produce a field strength greater than 100 uV/m (with
exceptions) at 3 meters from 30 - 88 Mhz. 3 milliwatts will produce
*1,000 times*, or 60 dB greater than, this amount when connected to an
isotropic antenna. Hook it to a dipole to get another few dB. The limit
for class A digital devices (one class of unintentional radiators) is
the same in that range, according to 15.109. So don't think that just
because you consider a signal to be QRP that it's legal.

FYI, I checked the MFJ-269 manual, and it claims: "a relatively pure
(harmonics better than -25dBc) signal of approximately 3 Vpp
(aproximately 20 milliwatts) into 50 ohms."

So my measurement of 3 milliwatts on the wattmeter could have been
low.

Bob
k5qwg



That said, I agree that chances of prosecution are zero for using these
devices unless serious and/or intentional interference results. And I
strongly agree with the folks who have said that the last thing you want
to do is force a specific ruling on the matter from the FCC.

Roy Lewallen, W7EL

During the 1960's I engineered the antenna systems that flew on the early TIROS weather satellites. The
antennas radiated both RHCP and LHCP. In the earthward direction the gain was approximately 3 dBi. At the
ground station I operated the antenna had a 16 dBd gain at the beacon frequency of 136 MHz The beacon xmtrs
output power was 5 mW. While the satellite was at maximum slant range (just over the horizon) of 1800 miles,
the signal level from the beacons was several dB over S9 on R-390 receivers with their associated frequency
down converters.

Walt,W2DU

Perhaps the answer here is to only use the analyzer on bands that are
not in active use at the time, like say Noon on 75 meters. I'm
speaking of when propogation is dead on thise bands because of time of
day.

Would the legality of it change? Probably not, but by doing it that
way you would have minimized the possibility of intererfering with any
other users that could hear you.

On Sat, 25 Aug 2007 19:42:26 -0400, Walter Maxwell
wrote:

On Sat, 25 Aug 2007 08:31:08 -0500, Bob Miller wrote:

On Fri, 24 Aug 2007 18:50:30 -0700, Roy Lewallen
wrote:

Bob Miller wrote:

I have an Oak Hills Research WM-2 QRP Wattmeter, which includes a
0-100 milliwatt scale.

With an MFJ 269 Antenna Analyzer hooked to the transmitter side of the
wattmeter, and an MFJ dummy load hooked to the load side of the
wattmeter, I get a reading of 3 milliwatts forward, 0 milliwatts
reflected.

Not sure whether the FCC is concerned with signals at the 3 milliwatt
level...

Most if not all the part 15 rules are defined in terms of field
strength, not power. 3 mW is way, way more than enough to exceed some of
the limits on some frequencies, when connected to even a poor antenna.
For example, Part 15 shows, in 15.209, that intentional radiators aren't
allowed to produce a field strength greater than 100 uV/m (with
exceptions) at 3 meters from 30 - 88 Mhz. 3 milliwatts will produce
*1,000 times*, or 60 dB greater than, this amount when connected to an
isotropic antenna. Hook it to a dipole to get another few dB. The limit
for class A digital devices (one class of unintentional radiators) is
the same in that range, according to 15.109. So don't think that just
because you consider a signal to be QRP that it's legal.

FYI, I checked the MFJ-269 manual, and it claims: "a relatively pure
(harmonics better than -25dBc) signal of approximately 3 Vpp
(aproximately 20 milliwatts) into 50 ohms."

So my measurement of 3 milliwatts on the wattmeter could have been
low.

Bob
k5qwg



That said, I agree that chances of prosecution are zero for using these
devices unless serious and/or intentional interference results. And I
strongly agree with the folks who have said that the last thing you want
to do is force a specific ruling on the matter from the FCC.

Roy Lewallen, W7EL

During the 1960's I engineered the antenna systems that flew on the early TIROS weather satellites. The
antennas radiated both RHCP and LHCP. In the earthward direction the gain was approximately 3 dBi. At the
ground station I operated the antenna had a 16 dBd gain at the beacon frequency of 136 MHz The beacon xmtrs
output power was 5 mW. While the satellite was at maximum slant range (just over the horizon) of 1800 miles,
the signal level from the beacons was several dB over S9 on R-390 receivers with their associated frequency
down converters.

Walt,W2DU

"Jimmie D" ) writes:

I think I remember a test conducted to see how much power it would take to
communicate across the United States coast to coast. They started out making
the contact at near legal limit and were still able to detect the signal at
just a few milliwatts. As I remember a few was less than 10. I am sure this
was part of a ham magazine article from many years ago. perhaps someone else
here knows the details better than I.

Don't forget that the rise of QRP activity forty years ago came due
to the realization that you didn't always need high power.

ANd one subset of QRP is to try to communicate with as little power
as possible. Sometimes that was deliberate, dropping power until
the signal was no longer receivable at theother end.

Michael VE2BVW

Jimmie D wrote:

...
I think I remember a test conducted to see how much power it would take to
communicate across the United States coast to coast. They started out making
the contact at near legal limit and were still able to detect the signal at
just a few milliwatts. As I remember a few was less than 10. I am sure this
was part of a ham magazine article from many years ago. perhaps someone else
here knows the details better than I.


Jimmie

It seems to me, many here have suggested there are "tons" of active hams
out there; some have even went so far as to claim the bands are "crowded."

Surely, taking in to account the above, the few brief milliwatts from an
analyzer are of no real consequence amongst this "rf pollution" ... and
ten milliwatts would never make it across such a country of such active
hams.

Regards,
JS