Most people I know who repair their boatanchors have relied on the HP 410C.? These are readily seen for sale with the RF probe and these have been converted to solid state.? See
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Ashley repairs and makes custom boards for the 410C,? I have 2 from her and they are well worth it .? There is also a SO-239 coax interface adapter available where you can use the RF probe to directly measure transmitter output.