Re: Balloon breaking previous records U3B-25

HF
 

Hi Dave,
Thanks for the mass data on the tripole vs trap dipole options.  If the 7.5m element had a trap in it, it would get a little shorter for resonance because of the inductance of the LC trap that's below resonance, as you mention.  But that's a very small mass reduction and 0.3 grams is a big mass addition!  If it were to be pursued, one way to tune it would be to set it up on a regular transmitter with a feedline to the SWR meter or antenna analyzer, hung out in the open as high as possible.  Once the trap location and overall length are set, transfer it to the balloon transmitter.  I've done something similar to this when making parasitic elements from wire for a Bird-Yagi-Uda where the wire for the parasitic element is different from the material used for the DE.  I tuned it as a dipole at the approximate height where the BYU would be installed, then added and subtracted 5% from the length to make the director and reflector.
Cheers
Halden VE7UTS

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