Owen Duffy wrote:
XMTR -- 2m of RG58 -- Bird43 -- 1.2m of RG213 Bird43 -- 20m RG6 (75 ohms) -- antenna.

I don't have any argument with your results. Try this instead.

XMTR -- 2m of RG58 -- Bird43 -- 1.2m of RG6 Bird 43 -- 20m RG6 -- antenna

The second Bird will NOT indicate the actual SWR on the RG6.
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73, Cecil http://www.qsl.net/w5dxp