LED lighting has the potential to become the main MF/HF noise source for us. FCC *radiated noise* limit testing can produce much lower measured levels than some consumer installations. The driver for
LED lamps no doubt comply with FCC conducted emissions. The noise is almost entirely differential mode. Think of a signal on an open wire t-line; it does not radiate (much). But, the asymmetry in the
My calculations assume that the LED lamp conducted emissions are at the FCC limit at a single frequency in the 160 meter band. This is not real world. I'll buy a lamp and characterize the conducted e
I did some research and Maxim makes ICs for offline LED lamps such as the Home Depot lamps. The switching frequency is 50 to 330 kHz and the incoporate frequency dithering to reduce EMI. The standard
Dan that is how I do it and have measured the base referred ground loss resistance of my 30' vertical to be around 5 ohms. _______________________________________________ UR RST IS ... ... ..9 QSB QS
Roy, you didn't specify the vertical length of your inverted-L but I'll assume it is 50' and that your base-referred ground loss is 5 ohms. Using NEC-2 for the 1/4 wavelength inverted-L I get a 2:1 V
The program W6ELProp gives the take-off-angle needed for any path. Looking at 80 meter paths (it does 801-0 meters) the angles for DX paths are in the range of 3-15 degrees. Dave WX7G _______________
If the radiation at 3 degrees is -8.9 dB relative to the maximum amplitude we can still work DX. _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
I use #14 stranded THHN wire from Home Despot because it's easy work work with. _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
The W7NQN line filter is a differential-mode filter. You need a filter that is designed for common-mode filtering. _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw?
I don't like diff mode only filters because they have diff mode to common mode conversion due to component tolerance. I don't see a fuse in the NQN filter and it us rated for only 7 amps. To be used
Tom, I don't doubt that you performed the cable TI measurement correctly but I have seen folks take data that is actually the TI of the test fixture and not the cables under test. What TI impedance d
20 uH should be sufficient at the base of a 1/4 wave length vertical. Such an inductor can be close-wound with insulated #4 wire, diameter 8", 8 turns. It should survive intact except for the insulat
30 watts is correct for 1500 watts in a 50 ohm system and a coil Q of 226. The power loss is 0.1 dB and the coil temp rise is around 20 deg C. _______________________________________________ UR RST I
My mistake. Now then, for lighting we don't really want much inductance between the antenna and ground. For a 100 kA strike rising in 2 us 1 MV is developed across 20 uH. Instead we want a sturdy spa
I agree with Tom and Bob that the big, heavy choke is not needed. Even it offers too much inductance to be an effective lightning path. A spark gap is the thing to use across the choke or shorted 90
Yes a direct hit should vaporize a spark plug. For a 100 kA hit two 1" diameter rounded steel balls may survive. Note that Ross Engineering uses carbon balls on their spark gaps. At 50 kA/us every in
A low impedance tower ground is important. Google TOWER FOOTING RESISTANCE for an IEEE ppt. on this. I would aim for a couple of ohms. That means several long rods. __________________________________