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OLD BIG STICK DISSECTION AND STUDY

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darticus

Active Member
Oct 17, 2011
104
4
28
Trying to see what makes an antenna work.
I was given this antenna but it had a high SWR. I replaced the screw on section on the bottom where the coax connector goes on as it was bad but still has a bad SWR.
Cutting windows into the sides until I found the workings that was causing a short from the ground to the top where the whip screwed in. Here is some pics of the mess. The resistor, I can't see
colors too good, and not sure of the cap size.
Can you tell what the size of the cap is? It reads .38n on the 200n selector on the multi meter. Is it electrolytic or mylar? Can I replace with any cap? This resistor read .8 ohms with my meter. Don't think this is right. Maybe you can see better than me. Colors look like gray gray blue gray wide silver or gray. I know if I replace the cap and resistor it will work! This is an old BIG STICK. I do have another big stick that works. Ron
 

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BIG STICK

Yes that"s a silver mica capacitor and the resistor looking thing is actually a wirewound choke search online for the color code to reveal it"s value check
the connections from both sides of the coax below these parts and see if both have contact with the so239 at the bottom of the antenna

RCB
 
Looks like your problem is at the coax cable completely corrored,I have the same trouble with an old A-99,replacing the coax cable with a new section and the SO-239 female connector fixed the problem,I will replace the capacitor and the resistor too in your case,the A-99 matching circuit is a little different
 
All things considered, I think you'd be better off throwing it away. That 'window' has destroyed the structural strength of the thing, for one reason. Save the cap and other parts if you want, but from the looks of th corrosion present, who knows what else may be wrong.
- 'Doc
 
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That seems to be a choke or a coil. I think the old big sticks were 1000 watts. How can I get a coil like that? I think I can epoxey and fiberglass the windows and be able to use it. I need to know how to get a choke like that. The corrosion is in just that 1/2 inch area and can be cleaned up.
Just think I can fix it and learn something. Maybe I can get it working. The resistor is a coil of some type . How can I find out? calling the company today. Bet they don't know!
Maybe I can explain it better. When I put a wire on the coax 239 screw on at the bottom and connect it to the metal where the whip screws in there is a short causing the top whip to be grounded and a very high SWR. The short seems to be accross the coil as it reads short. I have another big stick and there isn't any short from base ground to whip connector. Is there a way to tell the size of the coil from measuring the good antenna? Is a coil the same as a choke? Thanks Ron
 
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darticus said:
That seems to be a choke or a coil. I think the old big sticks were 1000 watts. How can I get a coil like that? I think I can epoxey and fiberglass the windows and be able to use it. I need to know how to get a choke like that. The corrosion is in just that 1/2 inch area and can be cleaned up.
Just think I can fix it and learn something. Maybe I can get it working. The resistor is a coil of some type . How can I find out? calling the company today. Bet they don't know!
Maybe I can explain it better. When I put a wire on the coax 239 screw on at the bottom and connect it to the metal where the whip screws in there is a short causing the top whip to be grounded and a very high SWR. The short seems to be accross the coil as it reads short. I have another big stick and there isn't any short from base ground to whip connector. Is there a way to tell the size of the coil from measuring the good antenna? Is a coil the same as a choke? Thanks Ron
Click to expand...

Ron, where at on the antenna is this device? Is it at the base or near the top of the first section? How about a picture showing this?

I always thought the BS was probably a sleeved dipole inside.

That thing will probably work to test it if you just add a wire to the tip equal the top element and hang it in a tree. I cut inside an A99 and fix a bad solder job, and hung it up, and it worked, but I took it completely apart up to the top of the first section.

Or, if you don't want to take it all apart to test, just put it together and hang it up. You might have to support these delicate parts somehow, from just hanging out there.

Thanks
 
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The choke or coil seems to be a gray gray blue gray or gray gray blue gray gray. Here is a drawing. THIS STUFF is by the top of the bottom section. Ron
 

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That's a high value resistor, not a coil, and serves as a connection to ground for impedance matching. The short section of coax below it also serves in that impedance matching.
Is that a good way of doing that impedance matching? No. it isn't, but it 'works'. If you'll remember, that antenna was recommended for use with a particular length(s) of feed line. That was another means 'they' used to make that antenna 'seem' so good, and make it usable.
It isn't that hard to 'fool' an SWR meter, and that was how most people measured the 'worth' of an antenna (and still do, unfortunately).
Do your self a favor, trash it.
- 'Doc
 
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darticus said:
The choke or coil seems to be a gray gray blue gray or gray gray blue gray gray. Here is a drawing. THIS STUFF is by the top of the bottom section. Ron
Click to expand...

That is what I guessed after looking at your pictures. So in some ways it is similar to the Gain Master in that it is center fed and uses a capacitor, with the exception of the choke at the base.
 
THANKS EVERYONE FOR YOUR HELP! I want to get this working with a low SWR as it was back than. Than fix the cutouts and display it. I can't beleive the Shakesphere co. got back to me with this great info. I must have found a worker that knows about this stuff.
This antenna was discontinued back in 1981, but the capacitor is 180 pf (picofarad) and the Inductor is a .68 uH (micro-Henry).
NOW how to get these parts. We may get this working. Ron
 

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