The theory I’ve read and my recent practical experience supports that. With my new RigExpert AA-35 I measured the VSWR of my 20/10/6 linked dipole in the back garden and found the ‘min’ shifted a lot [often outside the band!] if I changed the inverted V angle by much (e.g. by tying the wire ends to trees instead of pegging them to the ground). BTW: the AA-35 also found an intermittent connection at the ‘rig end’ RG174/BNC [so worth the investment in an AA].
Been reading a lot online about CMC and CMC chokes in the last 48 hours. And I get confused about CMC chokes and 1:1 baluns. It seems they do different things but there can be some overlap. Both my linked dipoles have 1:1 baluns (for my unbalanced coax feeder). I read a balun can afford some CMC rejection. But maybe not enough in some situations?
My 60/40/30 inv-v is designed for the ends to be “1x FMF walking pole height” or “1 standard Scottish hill fence” above ground The 30/20/17 was designed with 5m cord end pieces to get the angle right. I had 50m of 1.5mm yellow Nylon cord so no problem making long ends and they wind up to nothing much. This ensures the V is correct. Like you, I was surprised how a small change in angle makes such a change in the match.
That’s what I used for the CMC in the picture I posted above (that toroid + BNC sockets fits nicely in one of the small ABS boxes that SotaBeams sell). I have noticed a little warmth after running 10w through it with the MPAS Lite, so I think its definitely doing something. Not enough to worry about the lost RF though.
Yes I’ve wondered about that - if you flip the feed round so the CMC is at the radio end I wondered if the coax outer would act as a bit of a counterpoise. I might use that as a fallback in the event I forgot my radials
I am using a plastic cable drum that arrived with either rg174 I had purchased or ethernet cable supplied for work, it holds 15m para cord, 20m of sota beams HD wire and 10m of mini 8 feeder total weight is 1.5kg.
This setup is only used close to the vehicle whilst away with work and has not been used for SOTA activations.
The 30/20/17 was designed with 5m cord end pieces to get the angle right. I had 50m of 1.5mm yellow Nylon cord so no problem making long ends and they wind up to nothing much. This ensures the V is correct. Like you, I was surprised how a small change in angle makes such a change in the match.
