GPS CAble Length Question

After a 17 year tenure the antenna on my GP 35 has bit the big one. It still works, but the threaded section that holds it to the mast - won't. So, I purchased a new GPA021S to take it's place, problem is it came with a 10" (that's - inch) cable which won't quite make it to my unit. So. Is there a reason all of the factory cables are either 10 pr 15 meters? Would it not be feasible to make a cable out of - say - RG6X that was maybe 3 or 4 meters long and would that affect reception? If that's doable, should I splice the cable and use the factory supplied fitting for the GPS end, or can I buy the appropriate fittings somewhere? Grazzi!

The GP21 has a 10 meter cable and the GP21S has a "short" cable. It is designed for commercial boats where the antenna replacement has a connection close to the antenna for ease of replacement. You can talk to your dealer about buying an TNC extension cable made of RG8X and it will work perfectly.