Better late than never.
I did some tests on an HP Network Analyzer regarding the multiple adapters subject.
The results were kind of interesting. Here's a zip with some not-so-high quality pix.
There is a pic there showing the adapter 'rig'. It's a mix of 'N', 'BNC', and some 'TNC' connectors. There's around 25 connections in this chain.
The names of the files describe the measurements. I never did buy into the whole .25db per connection loss. The vertical scale on all pix is 1dB and the freq. span is 500 mHz....50 mHz/div.
At 450 mHz the total loss is only .16 dB..... a far cry from the estimated 6 ish db of loss if you go by .25/connection. Much more loss though at 2.45 gHz center, but still only 2.1 dB @ 2450 mHz. The curve is much more rough though, probably a lot to do with the adapters rapid change in diameter.
I also included SWR measurements for 450 & 2.4 as well.
(Back to work.)