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Post by zman on Jun 10, 2009 19:11:30 GMT -5
I have been playing around with my Astrobeam and i cannot get a decent SWR whatsoever no matter what I do. Adjusting the driven element, changing coax, using different coax, using small jumper coaxes of a different type, tuning the antenna away from metal, raising the antenna away from the ground, and pretty much anything else i know provides no changes. What am I doing wrong?  I do know the antenna doesnt have the dual RG 59 jumper coax. could this be the problem? I about to throw this antenna across the yard and cut it up for scrap aluminum! |
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Post by Marc on Jun 17, 2009 14:38:07 GMT -5
I would say that the RG-59 matching harness is the prob.
Will prob need it to get the standing wave down.
Marc
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Post by zman on Jun 19, 2009 21:16:42 GMT -5
I have tried everything. I am about to throw in the towel.
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Post by zman on Jun 22, 2009 21:42:46 GMT -5
Its going into my scrap aluminum antenna parts pile. I am done messing with it.
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Post by badnews456 on Jun 24, 2009 2:32:08 GMT -5
I had one in the past it is junk get a v quad . BADNEWS
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Sandbagger
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Post by Sandbagger on Jun 24, 2009 7:01:38 GMT -5
I had one in the past it is junk get a v quad . BADNEWS Perhaps you had a bad one? I also had an Astrobeam back in the 80's and it was a fantastic performing antenna. Better gain and a deeper null than a standard 3 element. Far more back rejection than a PDL or even a Moonraker 4. I could drop the signal of a guy 7 doors down the street from me, from a +30db over S9, down to a little over S9. People 3 miles away could step over him. I could unscrew the coax from the back of the radio and get a stronger signal from him. Truly amazing. I'm sorry I got rid of it when I moved. I'd love to have it back now..... |
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Sandbagger
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Post by Sandbagger on Jun 24, 2009 7:04:09 GMT -5
I have been playing around with my Astrobeam and i cannot get a decent SWR whatsoever no matter what I do. Adjusting the driven element, changing coax, using different coax, using small jumper coaxes of a different type, tuning the antenna away from metal, raising the antenna away from the ground, and pretty much anything else i know provides no changes. What am I doing wrong? I do know the antenna doesnt have the dual RG 59 jumper coax. could this be the problem? I about to throw this antenna across the yard and cut it up for scrap aluminum! I had an AB back in the 80's. I remember it had a length of coax that was evidently used to match the impedence. It was not RG59. It was thick like RG8. I'm thinking it was RG11, which is 75 ohms. If you don't have that matching stub, that's likely your problem. |
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Sandbagger
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Post by Sandbagger on Jun 24, 2009 7:05:11 GMT -5
Its going into my scrap aluminum antenna parts pile. I am done messing with it. Send it to me! I loved those antennas. ;D |
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Post by Sniper..Unit 305 on Jun 25, 2009 7:34:54 GMT -5
Its going into my scrap aluminum antenna parts pile. I am done messing with it. Send it to me! I loved those antennas. ;D Heck if you don't send it to Sandbagger then give me a pm, I sure would like to have it for spare parts ! Sniper |
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Post by zman on Jun 29, 2009 12:23:48 GMT -5
No its staying here. I simply took it apart and have it all stashed away neatly in the garage rafters. Oh someday i will take it back out and see what i can do for it.
Sandbagger; did you have the pigtail coax on your Astrobeam when you had yours up?
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Sandbagger
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Post by Sandbagger on Jun 29, 2009 21:37:59 GMT -5
No its staying here. I simply took it apart and have it all stashed away neatly in the garage rafters. Oh someday i will take it back out and see what i can do for it. Sandbagger; did you have the pigtail coax on your Astrobeam when you had yours up? Yes, there was about a 3 or 4' pigtail included. It was thick like RG-8, but it was not RG-8. I'm thinking it may have been 75 ohm cable, but I'm not certain. |
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Post by zman on Jun 29, 2009 22:01:01 GMT -5
Ok. Now the NOS Astrobeam i had in 2002 did have a RG-83 coax pigtail. I thought the RG 83 was a bit odd, but now that you mention it that was proabably used to bring the SWRs down. I sold that NOS Astrobeam for about 150.00. I wish i had kept it though.
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Post by Sniper..Unit 305 on Oct 17, 2009 14:36:53 GMT -5
No its staying here. I simply took it apart and have it all stashed away neatly in the garage rafters. Oh someday i will take it back out and see what i can do for it. Sandbagger; did you have the pigtail coax on your Astrobeam when you had yours up? Yes, there was about a 3 or 4' pigtail included. It was thick like RG-8, but it was not RG-8. I'm thinking it may have been 75 ohm cable, but I'm not certain. I had PM'ed Sandbagger and tossed around the harness question on the Astrobeam also. Quite a few of us locals were trying to figure out the harness question also since my match was NOT good at all...anywhere without my antenna tuner. The match was a 3.7.1 at its lowest on 27.235 where it was its lowest, and that was without a harness. I was under the belief that a friend from 30yrs ago had his astrobeam up without a harness, but I had to be mistaken on that assumption. We found out that some of the astrobeams came with twin rg59u 75 ohm cables at 6' long wired in parallel for an outcome of 35 ohms. This cable harness was then inclosed in a shrink tube and mounted at the antenna to match it in. Some other astrobeams came with a single length of rg83u (same thickness as rg8u) at 6' long and this cable is 35 ohms to begin with. These differences must have occurred in different time periods when the antennas were built. I do not believe that the rg83u cable is still available but very good rg59u IS. I made a harness out of the rg59u cable carefully measured at 6' per cable and then connected the braided ends together and then the center leads together and soldered them into their connectors....1 on each end of course, to make a parallel harness. I connected an swr meter directly after my radio and then put the astrobeams coax directly into it and measured the swr at the channel that I got the lowest reading which happened to be 27.235. The reading I got here was 3.7.1 (and this was the lowest swr WITHOUT the harness). I then put my homemade harness on the antenna and I NOW have an swr of 1.2.1 on 27.235. Of course the swr goes up the higher or lower I go in frequency which is exactly what you would expect. I would imagine that 1 single length of rg83u would duplicate what the dual rg59u cable harness has done, but I do not have any to try it. I had called my tech before making up the cable harness to see what he figured the outcome would be if I coupled the 2 rg59u cables together and he had said it would be equivalent to 35 ohms once paralleled. I had my fears when it came to keying the microphone to check the swr for fear of popping a final output, so I did the test with my Yaesu 901 inline figuring the tubes could take allot more punishment than a transistor. Anyways, this worked out for me and I couldn't be more pleased with the outcome. Quite a few local friends were involved with digging up all the needed information on this and much of the thanks goes to them ( Don from Monongahela, Charlie from Jefferson Borro, Denny from Bridgeville, and quite a few other locals that I know were really working to dig up information on this), along with of course our own Sandbagger who started me thinking of the single cable deal and just what it could be and exactly what it did. So don't throw that astrobeam away or even put it aside, put it up and get it talking. This beam without a doubt has some very very impressive rejection and it will get out as well with very good results from my friends who have heard it local. Quite an impressive beam in a small package. Sniper |
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Sandbagger
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Post by Sandbagger on Oct 17, 2009 19:04:42 GMT -5
Yes, there was about a 3 or 4' pigtail included. It was thick like RG-8, but it was not RG-8. I'm thinking it may have been 75 ohm cable, but I'm not certain. I had PM'ed Sandbagger and tossed around the harness question on the Astrobeam also. Quite a few of us locals were trying to figure out the harness question also since my match was NOT good at all...anywhere without my antenna tuner. The match was a 3.7.1 at its lowest on 27.235 where it was its lowest, and that was without a harness. I was under the belief that a friend from 30yrs ago had his astrobeam up without a harness, but I had to be mistaken on that assumption. We found out that some of the astrobeams came with twin rg59u 75 ohm cables at 6' long wired in parallel for an outcome of 35 ohms. This cable harness was then inclosed in a shrink tube and mounted at the antenna to match it in. Some other astrobeams came with a single length of rg83u (same thickness as rg8u) at 6' long and this cable is 35 ohms to begin with. These differences must have occurred in different time periods when the antennas were built. I do not believe that the rg83u cable is still available but very good rg59u IS. I made a harness out of the rg59u cable carefully measured at 6' per cable and then connected the braided ends together and then the center leads together and soldered them into their connectors....1 on each end of course, to make a parallel harness. I connected an swr meter directly after my radio and then put the astrobeams coax directly into it and measured the swr at the channel that I got the lowest reading which happened to be 27.235. The reading I got here was 3.7.1 (and this was the lowest swr WITHOUT the harness). I then put my homemade harness on the antenna and I NOW have an swr of 1.2.1 on 27.235. Of course the swr goes up the higher or lower I go in frequency which is exactly what you would expect. I would imagine that 1 single length of rg83u would duplicate what the dual rg59u cable harness has done, but I do not have any to try it. I had called my tech before making up the cable harness to see what he figured the outcome would be if I coupled the 2 rg59u cables together and he had said it would be equivalent to 35 ohms once paralleled. I had my fears when it came to keying the microphone to check the swr for fear of popping a final output, so I did the test with my Yaesu 901 inline figuring the tubes could take allot more punishment than a transistor. Anyways, this worked out for me and I couldn't be more pleased with the outcome. Quite a few local friends were involved with digging up all the needed information on this and much of the thanks goes to them ( Don from Monongahela, Charlie from Jefferson Borro, Denny from Bridgeville, and quite a few other locals that I know were really working to dig up information on this), along with of course our own Sandbagger who started me thinking of the single cable deal and just what it could be and exactly what it did. So don't throw that astrobeam away or even put it aside, put it up and get it talking. This beam without a doubt has some very very impressive rejection and it will get out as well with very good results from my friends who have heard it local. Quite an impressive beam in a small package. Sniper RG-83..... That rings a bell. I remember it being as thick as RG-8, but not being 50 ohm. I'm glad you figured it out. I really liked my Astro Beam when I had it. I wish I'd never gotten rid of it. That thing had the best rejection of anything even close to it. I even saw better rejection than a Moonraker 4, based on comparisons with other people. A truly unique antenna, typical for Avanti. |
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Post by zman on Nov 18, 2009 0:57:15 GMT -5
Thanks guys!!! I still have the beam and its all tucked away for safekeeps. i talked to a CB shop owner that is very versed in antenna theory and he said that the later models did indeed come either with the RG 83 or the dula 59u coax harness. he has some of the harnesses in stock so all i need to do is pick one up.
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Post by zman on Dec 6, 2009 2:25:46 GMT -5
Well i got a harness and i ALSO got another astrobeam in the deal! The beam I just got is in geat cond and has the plastic end caps that are intact unlike the other one I have that was jimmy rigged. I kinda wonder if maybe the elements were somehow contacting the boom on the other astrobeam that was rigged up. The shop owner told me that none of the elements can ever contact the boom and he said maybe that was the problem with my other beam and why i couldnt ever get the swrs down. The coax jumper is a 6' section of RG 83 coax. So when it gets nice out im going to try this other beam out!
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Post by Sniper..Unit 305 on Dec 6, 2009 12:56:45 GMT -5
Good to hear Zman, I think you will be really happy with the beam. I've been using mine daily and its a pleasure to have all the rejection that it exhibits along with decent gain on those weak stations further out. Don't know how I did without all this time.This summer I hope to get my Gizmotchy 4 up in the air to see how it will do compared to the Astrobeam. I have a feeling that the Astrobeam wont be beat in the rejection compartment by the Giz, but we'll see. Experimenting is half the fun! Sniper
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Post by zman on Dec 7, 2009 2:07:55 GMT -5
Hey Sniper, did you get that RG 59U pigtail with your beam when you got it? I got a section of RG 83 with my "new" Astrobeam. The shop owner said if i cant get it to match with the RG 83 to bring it back and he will let me try it with a section of RG 59U. I got it put together today and it looks goood but i didnt spend much time really tweaking with it as it was only 29 degrees outside, LOL. In fact, the astrobeam i got now was the shop owners he used for his shop radio and he had it mounted on the shop roof. He said he never had problems with the SWRs.
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Post by Sniper..Unit 305 on Dec 8, 2009 8:07:35 GMT -5
Zman I had to make the pigtail up myself after some exhausting searches for information on the different variants of the antennas setup over the 23ch to 40ch years. I and a lot of locals did quite a bit of research, along with Sandbagger, to come up with what was needed. Sniper
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I do know the antenna doesnt have the dual RG 59 jumper coax. could this be the problem? I about to throw this antenna across the yard and cut it up for scrap aluminum! 
