High SWR and signal decrease - antenna problem?

[Turbo T]

I've been recently having a problem that just comes and goes in terms of my 2 meter radio set up.

My set up consists of a Yaesu FT 2800M radio, a Ringo Ranger II antenna and 40 ft of LMR-400 coax. I keep an SWR meter in line with the radio.

I have noticed that sometimes my radios signal will decrease by 3 or 4 bars as opposed to normal and if I key up the SWR is over 5:1. Yet later on the same day without doing anything all of the sudden the signal strength will return to normal and the SWR will be at 1.3:1.

Since my antenna is mounted way up on a pole I haven't had the time to really trouble shoot. I have so far verified that there is continuity at the end of the coax between the center lead and the ground. I know this indicates a short.

However, since it comes and goes (and is not all the time) and also since the radios signal decreases (even on the strongest repeater that is 10 miles away and can be heard for miles) this has me wondering if this is a potential antenna problem...? How common do Ringo Rangers have issues such as mine?

I mean i could be wrong, but I would think if the coax itself were shorted (such as if someone stuck a pin in the coax) that the signal strength would remain the same.....right?

Thoughts?

Thanks in advance.

 

[IRock817]

I'm no tech by any means, but I think the coax will show resistance when hooked to the antenna.
Good luck

 

[Robb]

You might want to check the coax connectors on both ends very carefully. Some where it is going open - probably when wiggled. If not with the coax; then the antenna has a loose connection. One or the other - or even both. If you bought the kind of coax that has pre-installed crimp-on PL-239 connectors; then they may be the problem. You might want to do all of this before someone has to troubleshoot/fix your radio when the finals fail.

 

[W5LZ]

That Ringo Ranger will normally show a short is measured at the end of the feed line, or at the input of the antenna, it's normal. If you take a look at the matching system, that ring, and trace out the connections, you'll see they are a direct short. That's at DC, but not at AC, and all RF is AC. Your coax isn't pinned, and I doubt if there's anything wrong with it.
If there's a change in the impedance it's usually for some other reason dealing with the antenna, or feed line, or both. Something is changing physically. Best thing would be to take the antenna down and make sure it's all still there and still assembled correctly. Remove the feed line and check for it being shorted, or opened. It should show that it's 'open' if removed from the antenna. If it isn't, then you've found the problem. If it isn't shorted, then take a very good look at that antenna, that's where the problem may be. Anything loose, not like it was originally, anything changed? Also 'walk' the feed line to see if there's any pins, or other damage. Does it move a lot, check for broken places, anything different.
My money would be on the antenna having a problem of some sort.
- 'Doc

(In 40 some years, I've only seen coax 'pinned' once. It was mine, and I had done the pinning for a particular reason.)