I'm using a ATU200 ATU, that can operate up to 150 W and uses a weather proof case.
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I've mounted the unit with a coaxial connector output. Not as it is on the kit.
I've been trying to fix my unit for the last three weeks with no success.
I decide to rewind the tandem transformer and replace the diodes, as may people say to do ( changes to 1N5711). My antenna is on top of an apartment building, a random wire with the sequence of a 1:1 choke balun and a 9:1 unun.
I've tested the antenna with nanoVNA close to it. All Z values were ok for the ATU-100.
My problem is: if my ATU ( my version is weather proof and can be installed outside close to antenna), With the ATU on 14th floor and 38 m of RGC213 the tuning is almost perfect for all bands from 80 to 10 m, with an exception (1.8:1) on 20 m.
But, when it seats close to the balun/unun with a short (1.5 m of coaxial cable), the ATU is totally unreliable. It's useless! : ( Sometimes the unit enter on an infinite loop an never find the good combination.
The case where it is mounted is plastic made bud shielded on internal side with copper foil adhesive tape.
I'm giving up to use it close to the antenna!
I'm lost.
Anybody have an idea of what is going on??
