Replacement Cable for SYV-50-3

[AK-Survey]

Hello,

I'm looking to replace an existing cable as part of my company's GPS survey system. We have an external radio for increased range. The existing cable is labeled "SYV-50-3   8352M." I found this to be manufactured by Lianstar in China (link to product: http://www.lianstar.com/en/SYV-50-cable.php). We have this set up with TNC connector on one end, with the other end directly into our antenna base mount. I see no indication whether this is SYV-50-3-1 or 50-3-4.

What I'm looking for is a good replacement cable that would replace this as it gets very stiff in the cold. My primary conditions are sub-arctic to arctic use (i.e. needs to be flexible to at least -40F/C) and repeated flexing, even when cold. We don't plan on a length greater than 10 ft. I have been told by separate sources that this is essentially RG-58, and also that it is replaceable with LMR-240.

Can anyone give suggestions before we invest in a potential custom-built cable? We're running up to 35W, 450-475MHz.

Thank you,

David