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Rapid storage and deployment of 50ft RG58 coax

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 :slight_smile: 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.

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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 :slight_smile:

Jonathan

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Hi Mark

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.

Info from the side shows SD 200k from hafner spools SD200K Hafner Spools

Few pics below beer mat for size comparison


73
Graeme

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Works for me!

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