I've never seen an HF Yagi with an air core balun at the feed point. Such baluns for HF were typically a foot or more square! (The only ones I ever messed with were mounted in the shack to connect a single-ended rig output to a balanced feed line.)
By the 1980s ferrite baluns were very commonly used almost everywhere, so I'd put money on your having a ferrite balun on that yagi. If the balun was abused, physically, with too much RF heating or by moisture getting into the housing, it may be damaged. The same is true for traps. 73, Ron AC7AC -----Original Message----- Someone mentioned the baluns on older yagis were air-core. I have an older Hygain TH3mk4 with original balun (big black box connected to the hairpin stub and driven element. The antenna is probably 20-30 years old, so I wonder if anyone can tell me if it is likely air-core or ferrite? Any advantage in replacing it? I found that I had to use a tuner after installing it at 50-feet even with element lengths adjusted to min SWR per manual. Now I wonder if this may be due to an aged balun? The used antenna only cost me $75 so not a big investment. But it does seem to "work" DX OK. I worked T32 on 10m on Saturday with only 8w SSB from my K3/10. But eventually I will be running 300w so this may matter more. Note that the tuner is required on all bands 20-15-10m. 10m was the hardest and would not tune very well in any position of the driven element. Tuning was done with antenna pointed straight up when at ground level with reflector essentially at the ground. I expected some shift in resonance once the tower was raised (all antennas installed before raising with a crane). I suppose this may also point at bad traps (but for $75 it works). 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? DUBUS Magazine USA Rep dubus...@gmail.com ====================================== ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
