For those suffering from close down in the QRO position when using a
grounded antenna loading/matching coil at the base of the antenna, an
external LPF in the TX line will cure the problem. I acquired a Ropex
recently and on testing into my antenna found this problem and I know
other suffer the same. I do not have a cct of the rig otherwise I might
be able to do an internal modification to rectify the situation.
With the LPF added I can now load the tx into the 50 ohm configured base
loaded, grounded inductor at the antenna base.
The ARRL antenna h/book has the details for constructing a suitable LPF.
I use T200-2 cores and 1200v rated poly capacitors. This LPF will handle
up to 1kw of RF and is also suitable for other
73 de Mal/G3KEV