40 feet is close to one wavelength on 12 meters, so that would be a 'troublesome' length (a multiple of 1/2 wl).
If the choke is at the feedpoint, the feedline can pick up RF radiated from the antenna. Perhaps try it near the rig. Alternatively, try adding a 10 foot piece of coax to the feedline. Or, as Ron suggested, try attaching a 10' piece of wire to the ground terminal of your rig. The end of the wire should not be connected to anything and may develop a high RF voltage in operation. On 10/3/2012 4:50 PM, Barry wrote: > I set up a common mode choke with 3 turns of coax through 2 ferrites, similar > to the figure 2 on p. 18 of this document: > http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf > I placed it outside, near the feedpoint. it did not change anything. > > Geoff, I have 20-25 ft of coax outside and about 15 feet inside. > > Barry W2UP -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ ______________________________________________________________ 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
