Today I’m tuning the Yagi after raising it another 6–7 metres on the upgraded mast. As expected, the resonant frequency has shifted higher, so the job is to bring it back down into the right part of the band. Rather than starting again, I’m extending the elements slightly and trying a simple little loop on the ends – partly for RF behaviour, partly because it just feels like a neater way of doing it. This "loop fix" is not about current heating the ends – it’s voltage trying to escape. A sharp tip concentrates it like a lightning rod. Add a loop and suddenly nothing to see. Another way of looking at this is that at high power, a sharp element tip is basically trying to turn into a tiny plasma ball (corona discharge). If we round it off, it never gets to form = lot less heat.
This video covers:
dropping the tower again (of course…)
measuring and extending the driven element and reflector
a quick-and-dirty field method using an SWR calculator
checking and correcting alignment on the beam
dealing with wind, rope stretch and the realities of working at height
and a first check of the new resonance once it’s back up
There’s also a bit of discussion around:
why height changes tuning
why every part of a mast system is effectively a single point of failure
and how small gains (a few dB here and there) all add up to a noticeably better station
I’ve slightly overcooked the length – but it’s close enough for now and easily trimmed later.
Next job will be building a proper choke to replace the temporary one, and squeezing a bit more performance out of the system.
Thanks for watching – see you on the next one.
PS : the "loop fix"… It’s not current heating the ends – it’s voltage trying to escape. A sharp tip concentrates it like a lightning rod. Add a loop and suddenly nothing to see. Another way of looking at this is that at high power, a sharp element tip is basically trying to turn into a tiny plasma ball. If we round it off, it never gets to form. Easy. Callum.