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Cruiseomatic
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I've got a Solarcon "Antron 99" that I "want" to use. Note the want in quotation marks. It can hear but hardly transmit. Currently it is approx. 14.4 ft. from ground to tuning rings. Mounted to a steel pipe which is held to a galvanized fence post. A99 Base is grounded with wire down the post and not insulated from mounting post. SWRs will not change when the rings are turned now that I freed them some. I also have a 3 ft. whip on the same post for my PRO-164 with coax also grounded to A99 with a mirror mount for a 102" whip grounded to the same. Basically, I have a common ground for everything. Whether its all there or not, story doesn't change. I have another post with my SWR readings located here: http://forums.radioreference.com/antennas-coax-forum/220602-swr-mixture-what-gives.html
From what I'm told, It can barely reach across the Houston ship channel on the east beltway 8 side. And trying to shoot skip is nearly impossible.
Is this "antenna" that inefficient or is there a way I can set it up to work? I'm open to any ideas. Thought about isolating the post from antenna and just using the wire as the counterpoise. What do you all think?
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LtDoc
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That 'ground wire' isn't a counterpoise, it's only a ground wire for safety. The 'A99' (and Imaxx too) use the feed line as the counterpoise (or the 'other hapf' of the antenna).
I have no idea why those tuning rings aren't having any effect on the matching of that antenna. It means that something isn't 'right', though. So, taking a look at everything, the antenna it's self, the feed line, maybe the color of socks you're wearing, is a very good idea.
What kind of shape is that 'A99' in? If those rings were stuck, I have to assume it isn't very new, so what else could be 'wrong' with it?
I would think that getting across the ship channel down there would be quite a bit 'less' than that antenna is capable of, so there's got to be more going on than is apparent.
good luck.
- 'Doc
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Cruiseomatic
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IIRC, it is around 10 years old and been airborne since new. Fiberglass is "fuzzying" off at certain points. And it uses the feedline as the counterpoise? Wow. Well, I do have 14 ft. of it outside. 8-9 running down the post and 4 along the fence. Freed the rings to move about 5 threads either way. Maybe I'm moving them "wrong"? Instead of together they should be apart? Given current finances, Really can't get anything else and I need the height of this thing so a dipole is out. If I could, I would love to get an Imax 2000 for this setup. Coax is RG-8/U.
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LtDoc
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If it's just the 'outside' that's not in 'good' shape, then it's probably refurbishable. If the electrical stuff inside is also a problem, then the cheapest option is just trash it. Of course, that depends on how handy you are with fiberglass and electrical thingys.
At this point, since the thing isn't really doing you much good, it probably wouldn't be a loss if you tried to 'fix' it. Or, if you've got the means to do so, just use the top section as a typical 1/4 wave whip and that fence as the 'ground'/counterpoise.
If you've got a tree that over-hangs that fence, and enough feed line to reach, nothing says you can't just use plain wire of the correct length and that fence as an antenna. Lot's of possible options, you ain't 'stuck' yet.
- 'Doc
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Decent with electrical repair, Not so much with fiberglass. With the tree, Alot of times if not all the time, When a good storm comes through, Tress give up and start shedding. It would fall apart. Literally. If I went the 1/4 option, from what I've read, I would have negative gain with it. At least with this I have "zero". With the whole thing being fiberglass and glued shut, How would I "dissect" it to "fix" it without cutting it up?
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Cruiseomatic
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Got the thing down, Found out why the rings didn't work, ( They need to be together and these weren't. Looked like it but weren't.) Had the SWRs down to 1.4 on 1 and 40 and 1.3 on 19. I thought it was "perfect" although SSB was still a mess. Got it back up and mounted and now 40 is 1.7 and 1 is almost 2.5. Didn't help I dis-mounted and re-mounted this POS solo...Fighting 10 ft. of pipe and 18 ft. of swaying fiberglass is NOT fun. I'm about fed up with this thing. If this thing doesn't need a "ground", What would make it change like that? Only difference is when I adjusted it, it was 2 ft. off the ground and now it isn't. Really Really wish I could get an Imax 2000 and trash this A99.....Same company but ALOT better antenna.
ermin
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Cruiseomatic said:
Got the thing down, Found out why the rings didn't work, ( They need to be together and these weren't. Looked like it but weren't.) Had the SWRs down to 1.4 on 1 and 40 and 1.3 on 19. I thought it was "perfect" although SSB was still a mess. Got it back up and mounted and now 40 is 1.7 and 1 is almost 2.5. Didn't help I dis-mounted and re-mounted this POS solo...Fighting 10 ft. of pipe and 18 ft. of swaying fiberglass is NOT fun. I'm about fed up with this thing. If this thing doesn't need a "ground", What would make it change like that? Only difference is when I adjusted it, it was 2 ft. off the ground and now it isn't. Really Really wish I could get an Imax 2000 and trash this A99.....Same company but ALOT better antenna.
I have heard that these antennas occasionally have an internal electrical connection problem. By the sound of things that is the problem. I don't know if you can "non destructibly" take the fiberglass cover apart to fix the electrical part inside.
Might be easier to get another antenna
73
Ermin
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Cruiseomatic
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ermin said:
I have heard that these antennas occasionally have an internal electrical connection problem. By the sound of things that is the problem. I don't know if you can "non destructibly" take the fiberglass cover apart to fix the electrical part inside.
Might be easier to get another antenna73
Ermin
That's what it sounds like to me also. Took it back down. I was able to tune to get 1.0 SWR on 19 and 1.1 on both 1 AND 40. Once I stood it up, same readings came back as before... I even insulated the base from the mounting pole. Nothing. Rings don't help that much either. On the ground she'll tune perfect, Once airborne, She hates life...
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Cruiseomatic
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Found the problem. Bottom portion has no continuity. Replacing it Monday, hopefully.
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LtDoc
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Glad you found the problem.
Don't get too tied up with the 'gain' thing. It's nice to have, but certainly nothing to worry about a lot. There are gobs of those 'negative' gain 1/4 wave antennas in everyday use, they work just dandy. May not hear everything out there, but neither do the super huge 'gain' antennas. At the very worst, they would do better than a broken 1/2 wave, right? 
- 'Doc
Just for the #3// of it, when you replace that bottom section, tear the broken one apart to see what the problem was. Not a lot you can do about it, but it'd be nice to know.
prcguy
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Here is an article showing whats inside an A99 and it doesn't look to difficult to take apart. The top sections are just wire so you only have to take the bottom section apart to possibly fix it.
http://www.g0vqy.co.uk/pdf/a99.pdf
prcguy
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Doc, Tried to take it apart last night. Was told a method to try without cutting it apart. It was to heat the glue up on the bottom before the base and break it off. I did. It will barely turn and not budge. I banged the base and twisted. Nothing. Thinking of just using the dremel on it. Can't hurt. It doesn't really work. Which could explain why it acted so "inefficient" for so long. Could never really shoot skip, People had a hard time hearing me.... I hope this "new" section helps if I can get it Monday before class. It'll be no fun, Get the new section, get it to the house then have to sit in class for 3.5 hours before I can play with it......
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nanZor
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Cruiseomatic said:
And it uses the feedline as the counterpoise? Wow............................... I would love to get an Imax 2000 for this setup. Coax is RG-8/U.
Run, don't walk to this description of the common-mode issues and patterns with the A99 / Imax 2000 - it will be an eye opener! The following talks about it in detail at the bottom of the page, along with pattern plots:
See the patterns near the bottom of the page and note even what the "best case" looks like. This could save you from some hair-pulling.
prcguy
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EZNEC is a wonderful tool and can give amazing results of real life antenna performance, but only when the user inputs all the needed data and knows how to drive the program. I suspect W8JI has not completely modeled the feed point of the A99 based on the resulting antenna patterns.
His statement "Feedline shield current is 100% of antenna current" would explain the wild upward main lobes he gets, which emulates the radiation pattern of a wire that's many half wavelengths long and not that of a single half wave antenna which is what the A99 is.
I'll agree the antenna is not perfect and feedline decoupling is probably lacking a bit, but W8JI is claiming the coax is radiating as much as the business end of the antenna, which in my experience its not.
I've played with an A99 and compared it to a few other antennas on 10m like an original Hy-Gain Penetrator, Shakespeare Big Stick and a broad band military Bicone and at the distant horizon the A99 did just fine and as expected.
I also paid particular attention when tuning the A99 with more than one length of coax and did not see any change in VSWR that concerned me.
prcguy
hertzian said:
Run, don't walk to this description of the common-mode issues and patterns with the A99 / Imax 2000 - it will be an eye opener! The following talks about it in detail at the bottom of the page, along with pattern plots:
See the patterns near the bottom of the page and note even what the "best case" looks like. This could save you from some hair-pulling.
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nanZor
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prcguy said:
His statement "Feedline shield current is 100% of antenna current" would explain the wild upward main lobes he gets, which emulates the radiation pattern of a wire that's many half wavelengths long and not that of a single half wave antenna which is what the A99 is.
Not to nitpick, but note that that statement was for the 5/8 wave Imax 2000 with no radials. This is the same kind of pattern performance I get when scaled down to vhf/uhf 5/8 wave antennas sitting on a wooden box with no ground. Then again, I'm not W8JI, so I'll have to let him speak for himself.
I've played with an A99 and compared it to a few other antennas on 10m like an original Hy-Gain Penetrator, Shakespeare Big Stick and a broad band military Bicone and at the distant horizon the A99 did just fine and as expected.
Cool - was there any sort of groundplane or radials involved?
In any event, I think that the op might want to try isolating the mast, and maybe running a radial or two at least and compare before/after results..
prcguy
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No ground radials on the A99 I had and if it had a hot coax problem it was not very apparent.
Cool - was there any sort of groundplane or radials involved?
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Cruiseomatic
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1. How did this end up in the scanner antenna forum and 2., I cut that Anton I wanted to use up. Just the base though. I'm STILL waiting to get the new base for it. I did find the problem why the one I have wouldn't work. Corrosion all over the copper and the cheap coax used from the connector to tuning load had split the insulation and shielding. However, Looking at it, everywhere the article that was written about this antenna being exposed, had solder joints. Mine is soldered everywhere whereas the article writers hadn't. Hit-and-miss on Q.C. I suppose.
