I need to construct a heavy-duty choke to be installed from the feed point of my 160 meter vertical to ground, for static drain and for lightning protection. How large does the wire, form, and induct
It all depends upon how much survivability you want, nothing will survive a direct hit. Any 1.5 to 2.5 mH choke will suffice, just look at the safety choke in a commercial amp for the smallest choice
Phil, This is like any shunt or series choke problem. The choke needs to be several times the impedance at the insertion point. In a case like this you don't want too much choke, which many people t
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
One method of dealing with this problem, particularly if one is using an FCP, where the IMPEDANCE is higher at the feedpoint than a resonant feed, is to go to ground with a 5 meg 10 watt resistor in
That is only 226 Ohms at 1.8MHz and at 1500W will be dissipating about 30W in a 50 Ohm system but Phil didnt say how he is feeding his tower which is resonant well below 160M. Yes it will work as wel
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
That choke is probably too small and will change SWR, but thankfully reactance in reactances does not dissipate power. Reactance simply stores and returns energy. 226 ohms of resistance would be abo
70 turns 2" diameter over 4" length would be 100 uH, and with an air core and #16 magnet wire would have a Q of about 200 or so. That's 1000 ohms impedance, a few hundred thousand ohms parallel resis
No, it isn't. 1500 watts is 273 volts into 50 ohms. If Q is 226, and reactance 226 ohms, Rp is 51,077 ohms. 273 volts is 1.46 watts heat. To get 30 watts of heat with 226 ohms reactance, Q would hav
My Mistake: I misplaced a decimal. Q would have to be near ten in the coil with 226 ohms reactance and 1500 watts to make 30W heat, not near 1. The other numbers are correct. A Q of ~200 is about 1.5
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