I'd like to recommend to others my solution. An Alpha Delta Model TT3G50
While it may not be as inexpensive as winding your own chokes etc, it is a whole lot easier. I have a double male connector on the back of the K2/100/AT100 and it feeds the amplifier or antenna. I never move it. BTW I have a coax fed dipole and on 80 meters I deal with substantial SWR's when I get up to the fone band. Sometimes as high as 5:1 because my antenna is tuned on 3530 KHz. My amplifier, an Ameritron 811H doesn't like that, so I have a tuner, a MFJ 989B - this is the one to have, the coil is on a ceramic form and doesn't come "un-sprong" as other models do. Anyway, it has a switch in it to put your rig on a dummy load when not on the air. Between the two, it provides (I believe) an excellent measure of protection. TR, WB6TMY ____________ At 04:46 AM 11/14/2009 -0500, Don W3FPR wrote: >While that RF Choke is well and good from the standpoint of static >discharge, I strongly suggest you move it outboard of the KPA100. >With the original KPA100 design, there was a 100 uH choke located at the >antenna jack. That choke was removed along with the improved T/R switch >design. - The reason - that choke could (and in some cases did) couple >with circuits in the base K2 and cause a parasitic oscillation to occur, >especially when operating on 40 meters. >So while I do encourage you to use such a choke, I also encourage you to >mount it somewhere in your antenna system outside the K2/100 enclosure. >If you have an antenna switch, open it and install the choke at the >'input' jack. If you have an amplifier that is always in line, install >it at the amplifier input. Worst case, if you have no convenient place >to mount it in the shack end of your antenna system is to use a small >die cast box with a male chassis mount UHF connector on one side and a >female UHF jack on the other, place the choke in the enclosure, wire the >connector centers together, and mount the box directly on the KPA100 >SO-239 jack. > >As for the gas discharge tube, that may do a good job, but do calculate >the gas tube voltage rating assuming a 3:1 SWR at the 100 watt level - >it should not fire with that peak RF voltage. By my quick calculations, >a 200 volt breakdown gas discharge tube would be about right. >Mount the gas discharge tube at the same place as the RF Choke. > >For the best protection, disconnect the antennas when the K1, K2, K3, >KX1 are not in use - or even better use an antenna switch to switch in a >dummy load instead of the antenna. > >73, >Don W3FPR Tel: . . . 707-832-4304 ______________________________________________________________ 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
