Antenna rewiring

I recently rewired a mobile antenna so I could reroute the wire without adding to it with a splice. I added about 5' to the coax to get it to where I wanted without excess coax. I used some new Radio Shack RG58 coax I bought years ago, but I noticed the amount of shielding wire seemed very skimpy or pathetic. The question is, can that quality coax have a negative effect on my tuning the antenna? I get almost a flat SWR on channel 40 and a 2-1 on channel 1 and can't raise the antenna anymore. I can't add a spring because there is already one in the system. I have 2 other antennas I'm going to junk and thought about swapping coax and connector or is it a waste of time? I'm open to ideas.

 

Thanks for the input and I will do some checking with my multimeter but I don't believe I can remove the spring because it is part of the mounting system and the SWR readings say the antenna is already short so if anything I think I need a longer top element which I found on another center loaded antenna which I will swap out tomorrow. Me being a perfectionist is a pain when it come to settling for less. LOL Thanks again

 

Sorry my first post may have been miss leading. I did not splice two pieces of coax together because I know that is asking for trouble. The antenna originally had a 10' coax and I replaced it with a completely new 15' piece of Radio Shack RG58U coax and a New coax connector that I already had around my place. When you are retired and on fixed income you tend to watch how you spend your money. I'm beginning to see why Radio Shack in going out of business like all companies who cheapen their quality. The antenna was a New Scosche antenna from Walmart that was Cheapened up and junk out of the box but I couldn't return because I lost the receipt. That same brand antenna I bought years ago and had great success with but as usual they made it look the same but changed the internal design and I'll never buy it again. But it's physical size fit my application for my little daily driver. I've already spent too much money on this Hobby and will just use another one of my antennas and make it work. The original question was ( Will cheap coax have a negative affect on SWR ) I remember back in the day dealing with coax that had more shielding wire in it, and I will find some of that if need be. Thank to everyone for your response.

 

Just to let you all know I went back to my old Scosche antenna with the 10' coax shoved thru the passenger door and got a SWR of 1-1.1 on channel 1 and 1-1.2 on channel 40 and it was a Flat Liner on channels 17 & 19 the 2 channels I use most. That equals no signal loss from what I've read. I'll fix the other one when I find the good coax or use it for parts.