I wrapped my anteanna amp is self amalgamating tape and put it up the mast (I’v heard they are waterproof anyway … but I suspect the connectors are not)
200km … not that good, a simple dipole can achieve that
maybe the tube enclosing the coco is absorbing signal …
- Can you take a sample of the tube used to enclose the coco put it in a microwave oven alongside a cup water then zap it for 30 seconds - if the tube gets warm it absorbs microwave signals.
- repeat with a painted tube see if the paint is a problem.
It’s easy to make a bad coco - with the element lengths off if the velocity factor doesn’t match the cable
It could be worth trying a simpler setup as illustrated in ads-b-flight-tracking-f21/confused-about-antenna-design-t19969.html
I’m thinking of something like this with the vertical just stuffed into the top of amplifier (seal over with silicon caulk), and the earth plane wires soldered to a penny washer (or drilled copper/brass coin) fixed to the thread
https://farm9.staticflickr.com/8657/16333155950_afddce3083_o.jpg … that should give you 300-400km
You can tell what range should be achieveabl by going to heywhatsthat.com/ - say where you are, what your antenna height is, select ‘in the air’ set the altitude to 38000 ft. zoom out to see the ring.