Re: Measuring Resonant Frequency of Traps
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Although it may qualify as "fancy" equipment for the "desert island" scenario, an antenna analyzer can easily show you the SWR of a filter at a given frequency, and you can manually plot a curve if you like, or else just watch the values as you go up/down in frequency to eyeball it. I do this for building/tuning band pass filters: 50ohm load on one end, analyzer on the other. Works great.
On Wed, Dec 18, 2019 at 10:51 AM k6whp < k6whp@...> wrote: Thought I'd throw this out for the group. I got trapped [sorry!] into schooling some "Baofeng Techs" (FNGs) who are interested in getting into HF about building trap antennas. Of course, being new, they do not have the luxuriant array of test equipment we seem to stack up over the years so I wanted to suggest to them ways they could construct traps and prove out the resulting resonant frequencies of same.
They will be pointed to the appropriate theory, formulas, and internet calculators to derive the component values, inductance, number of turns, etc. but after they have built the traps, I wanted to provide them with a crude but decent method of determining the resonant frequency. (It would not do, after all, to have them wind a 20m trap resonant at 16 MHz.)?
Assume they have a brand new transceiver, can afford a decent VSWR meter, and can lay their hands on stuff like #47 panel lights, LEDs, wire, coax, etc. and know how to solder. They know ought of antenna analyzers, don't have a clue what a GDO is, and other "desert island" stuff like that.
Appreciate any ideas.
--
William, k6whp
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"Cheer up, things could get worse. So I cheered up and things got worse."
-- Ryan Flowers W7RLF
https://miscdotgeek.com
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