I've used RG8X, RG58, LMR400, and LMR400 ultraflex cables. Is there any cable that is in between these in terms of thickness/flexibility and loss? It seems like there's a big difference between the LMRs and the RGs.

I haven't tried RG213. Is that any good?

"Low Loss" and "Flexible" are usually mutually exclusive! I've used RG213 - it's exactly the same as UR67.

RG223 is quite nice, similar thickness to RG58 and double shielded with silver conductors.

I quite like Westflex WF103. They claim that the insertion loss is as low as 5 dB over 100 m at 100 MHz.

Eupen EC400 claims even lower 4.2dB/100m:-
http://www.broadcastwarehouse.com/eupen ... 46/product

Sounds obvious, but buying quality connectors and knowing how to put them on properly is key! The cheap ones often don't fit well and can give dodgy connections, or connections that are prone to failure.

Westflex 103 isn't particularly flexible but does give the best value for loss against cost. I had a good look around a while ago and couldn't really find anything which was as easily available and could match its price/ performance ratio.

Any thoughts on this stuff?

http://vi.raptor.ebaydesc.com/ws/eBayIS ... 3945905131

I use Westflex 103 and it's never failed me

Messi & Paoloni ULTRAFLEX 10
Works brilliantly low loss and flexible as fuck!