Don is totally right. But, cutting to the chase, put a 100K resistor across your coax before it gets to the receiver. Easy, no RX mods, just put a 100K resistor ... 1/2W will do fine ... into a PL259. Put a UHF T-connector on your radio, put the antenna on one leg, put your resistive PL259 on the other.
Trust me, you *CAN* fry the input stages to your radio and it won't even look like you're doing it as you are. Been there -- done that, more than once, we all learn slowly. :-) No bleed = charge builds up in the input capacitance, it will eventually take something out. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org On 9/8/2012 8:03 PM, Don Wilhelm wrote: > OK a bit of explanation is in order. The K2 (and K3 as well as the K1) > control power based on measuring the actual output power and adjusting > the drive to provide the requested power level. That means a device > capable of measuring the RF output is necessary. > Well, that is the wattmeter in the KPA100 - it uses Schotky 1N5711 > diodes because those have been chosen to provide the best response with > respect to frequency and power level. > > Yes, those diodes are a bit "tender" with respect to static. Those > diodes live right at the antenna terminals and are quite susceptible to > static charges. The K2 (K3) power control system will give you the most > consistent power control (because it is a closed loop), but to operate, > it must be able to measure the output power. and the diodes that do that > task are susceptible to static discharges. > > Yes, go out and find yourself some resistors between 22k and 100k and > connect them across your feedlines. > > Note that I do not care about the path to (earth) ground - while that > may be nice, IMHO it will not help with the equipment damage from > antenna induced static charges. Yes, the station should be connected to > earth ground, but for purposes of lightning protection rather than > static discharges from antennas. > > There are 3 grounds in a ham station - AC safety ground (see NEC > requirements), Lightning safety grounding (see Ron Block's papers at > Polyphaser,.com) and RF ground. The RF ground is the most elusive, > because it does not include any hard connection to mother earth. > "Ground" in this sense is a point of commonality, or a point where the > RF voltage is zero. That condition occurs at the feedpoint of a > balanced antenna - the zero voltage point directly between the feedpoint > terminals. > > OK, I am mixing a bit of the theoretical and the practical, but take to > heart, it is not hard. When the wavefront moves from the feedline into > the antenna, the conditions change from conduction (obeying Kirchoff's > laws) to radiation (obeying Maxwell's wave equations). Where the > transition point occurs is indeed a mystery. > > That has nothing to do with the "ground question".. Everything needs to > have a return path, and I believe that is valid for RF as well as for DC > conditions. This is the Kirchoff stance,, but there are those who argue > than the Maxwellian equations offer a better explanation. That may be > true, but there is little difference. > > My goal is not to "solve" this inconsistency, but just to add a bit more > information (OK, to justify my conclusions be they right or wrong). > > 73, > Don W3FPR > > On 9/8/2012 10:07 PM, stan levandowski wrote: >> Thanks, Don. I have a homebrew doublet with a gas discharge center >> insulator and I have been under the (apparently incorrect) assumption >> that I've been well protected from static buildup. I've also got a >> coaxial switch which is dialed into the dummy load when not in use. >> >> Guess, I better go out and buy a 22K resistor now and fnish the job ;) >> >> Appreciate the tip. >> >> 73, Stan WB2LQF >> >> >> On Sat, Sep 8, 2012 at 9:17 PM, Don Wilhelm wrote: >> >> >>> >>> The Gas discharge tubes are effective against large charges - the >>> ones I have will squelch a voltage in excess of 600 volts, but below >>> that level, they will do nothing. That 600 volt surge is enough to >>> take out the diodes in the K2 KPA100. The K3 has more protection. >>> but still should not be trusted when it comes to static charges. >>> >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.2197 / Virus Database: 2437/5257 - Release Date: 09/08/12 > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
