I don't have direct experience with cheap
knock-off / "generic" / made in China
But, I recommend against them, (and against even LMR-400 itself) for a few reasons...
a) LMR-400 is a bit stiff....has a solid copper-clad aluminum
center conductor, and a low-density-foam dialectric...and requires a bit of quality control to manufacture correctly....(as well as care upon installation
LMR-400 is not really a good choice here....if you need an ultra low-loss flexible cable, use LMR-400UF or Davis Bury-Flex....both use stranded-copper center conductor, and are more flexible, and more feasable for use in tight spots and/or where bending is required....
Further, if you are going to be installing you own connectors on LMR-400, you're apt to nick the copper cladding and expose the alum wire, giving rise to future connection issues / corrosion
b) In my 40 years in communications
, there are few constants...but one constant is:
and connectors always end up costing you more!!!
In addition to lots of Heliax, flexible cables I've used: Times LMR-240, LMR-400UF, Belden 9913, Davis "Bury-Flex", and many variants of mil-spec/"RG" series (213, 214, etc.), as well as non-mil-spec cables (RG-8x, etc.)....
And, I've worked on / repaired more systems with cheap cables/connectors, than I care to remember....
Spend the extra $50 on the "real thing"....and you'll be ahead of the game!!!
c) With the distances of cable runs on the average sailboat, the loss differences between "ultra low-loss" cable (LMR, etc.) vs. normal low-loss cable (Foam dialectric, etc.) vs. normal cable (mil-spec 213, etc.), are slight....so worrying about the last 1/10 of a db is only done by fanatics like myself...
d) Have a look at Davis RF, for all your cable needs....either bulk or pre-made assemblies....I've done business with them for years, great people!!!
Davis RF Co. - Coax Cables
Davis RF Co. - Amateur Products, Low-Loss Braided Coaxes
Davis RF Co. - Bury-FLEX Flexible Low-Loss Coax
Also look at Texas
Towers, they have coax and assemblies as well....and I've also done business with them...great guys there as well!!!
Texas Towers, Coaxial Cable Page
Texas Towers, Coax Jumpers Page
As you see, even if choosing ultra low-loss cable, the costs aren't too high....depending on how much cable you're looking at (maybe 100'???), you're probably going to spend less than $150.....
I do hope this helps...
s/v Annie Laurie