Is an Antenna Analyzer an FCC violation?
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
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