I installed a 2 meter ground plane antenna on my tower, up 40 feet. I tuned it to SWR of 1.3:1 at about 8 feet above ground with 30 feet of LMR200 coax. Then installed it on the tower well above obstructions with approximately 65 feet with 3 patched together lengths of feed line in an attempt to utilize ($$) what materials I have on hand (two lengths of LMR200 and one of LMR600). The SWR has jumped to 2.4:1. I have lowered and raised the tower a number of time attempting to adjust the antenna length to get the swr down with no success.
This setup involves 3 adapters/connectors not including the connectors at the antenna and transmitter.
I attached 3 #31 ferrite beads at the antenna which lowered the SWR from 2.6:1 down to the above stated 2.4:1.
This is probably not a good method for running a feed line. The only thing I can think of at this time is to run a single length of coax from the antenna to the wall, transition through the wall and a single length to the transmitter. This would remove 2 connectors.
With a single coax you had a good SWR but when adding coax (I think it is a female connector on both sides) the SWR went up. Definitely the problem is in one of the coaxes. Although it may also be a problem in the female connector that connects the coax.
What I would do is test the coax and see which one is bad and also the connectors. The best thing is a coax line without a tie, but I understand that you are using your other coax to save money, I also sometimes do things like that hehehe, 73’
Hmm…I think I will start with the last length of coax I added. For the most part I assemble my own feed lines. It is possible that the connectors may have a poor connection to the shield and or center conductor on either of both ends.
This lenght of feed line has a PL259 on one end and a SMA on the other to match the fitting on the LMR600 I had purchased preassembled. Those SMA connectors can be a bugger to assemble.
I had a home brew 2 meter half-wave dipole connect to the LMR600 earlier along with the feed line running to the radio. It was tuned to under 1.5:1 when assembled. When I installed it on the tower the SWR went up to 2:1, which I expected would happen. Rather than tune it up on the tower I replaced it the ground plane up on top of the center mast along with additional coax. Giving it some thought, the last addition of coax is a good place to start.
That is a possibility. Although, I took this measurement right after I raised the tower back up, before any weather exposure. The LMR600 is fitted with a weather proof N connector on one end and an SMA on the antenna end. I’ve kept the antenna end sealed up, but, I guess water intrusion is still possible.