Big Stick acting funny on 20......???

[WX2MIG]

I put this old Super Big Stick up yesterday, connected it with an old piece of Rat Shack RG-58, and tuned it up on 20 meters. I was able to get to tune up to a solid 1.2:1 SWR on CW with the key. Then when I switched to SSB and attempted to transmit voice the SWR's would start off flat, then quickly go whacky and shoot up.......
The station I was calling kept saying I'd start off strong then quickly fade, they thought it was band conditions, but I know different, it was the antenna...

Now like I said, the coax is of questionable quality, as are the PL-259 connections, it could be the wire, but I was also told these antennas have a capacitor and resistor installed inside, and if I access these items, and jump them out it will fix the problems. According to this source, about a foot below the connection between the top and bottom sections is an air pocket that can be seen with a strong flashlight, this is where I'll find the offending capacitor and resistor. I need to cut an access hole in the fiberglass, clip out the cap, and resistor, jump out their connection points, then patch the hole with fiberglass. This fix is "supposed" to allow this antenna to not only tune up cleaner on more frequencies, but also handle more power.....

Have any of you guys ever heard of this fix, or done it.....?

I figure after next payday I'll pick up another length of new Rat Shack coax with factory PL's installed, and try it again, if the problem remains, then it's definitely the antenna and not the wire.

Also, I was able to tune this antenna up fairly flat on 20 and 17 meters, right around 2:1 on 15 and 12 meters, but I could only get it down to around 3:1 on 10 meters, and my TS-130S would only transmit about 10 watts out, now this radio has been able to punch out 50 to 60 watts with a 3:1 match on other bands, but on 10 meters it'll only do 10 watts....what's up with that.....

 

[W5LZ]

First thought is that you may be expecting more than can reasonably be expected from that particular antenna. It may be -usable- on 20 meters but it was never designed for that band so expect less than optimal performance.
Second thought, and not much of one since I've never torn one apart to find out, is that while a capacitor can be useful, why would anyone want a resistor in a vertical antenna, it sure wouldn't be useful. And then thinking about that capacitor, wonder what it's voltage rating is/was? Especially when used out of it's expected frequency range, that voltage rating better be quite high. From your description, it could certainly be at least part of the problem.
'Rat Shack' coax. While I can't say any coax with the 'Tandy' name on it is worth anything anymore, I kind of doubt if it's a significant cause of what's happening. Just not very likely, which doesn't say it can't be at least a part of it (but I doubt it).
Reworking a fiberglass antenna is going to be such fun! It's just not be worth the trouble for me (itchy/scratchy/allergic reaction to fiberglass sort of thingy). Sell the thing and put up a vertical of the same length. You'll get a dollar or two out of it, and at ~least~ the same performance from some other vertical.
You can make almost any antenna work almost anywhere. The key word in that is 'almost'. With the way you seem to have things put together, you may have just found one'a them 'almost's. Wanna try something a bit different? Do so! Quit when it isn't fun anymore.
- 'Doc

 

[Highlander_821]

Never mind, wrong antenna.

 

[SR385]

What I'm guessing is, you are saturating the matching system once you get to operating on it. Once you heat them up, like a cheap balun design, the properties change pretty wildly and you will see fluctuations like that.

You would be better off feeding plain old wire...e.g. bypassing that matching section with a jumper as advised.

Just because you have a match, doesn't mean you are radiating anything ;-).