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#1
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cushcraft A3S Tribander HF beam
Just bought a secondhand A3S 3 element HF beam (bought it really cheap but
its as well!) The fibreglass isolator is cracked so managed to get a new isolator. What suprises me is that the isolator is made of fiberglass tube rather than being solid especially as it must take quite a bashing in gales. Question to owners of this or other beam with a similar isolator: Anyone replaced it with stronger material and if so can you send me info (taking out the spam trap in the email address) Thanks in advance. |
#2
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Les,
Hygain uses the same insulator for several of their antennas, and it can be a problem with all of them. Replacing it with a 'solid' insulator of some kind is one solution. I'm still hunting for a replacement for one for an 'R-7' (the only difference is in the length). Thought about using 'Delrin'(sp) or some other type of plexiglas/perspex, but haven't found a source yet. Good luck... 'Doc |
#3
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On Sun, 25 Apr 2004 07:58:12 -0500, 'Doc wrote:
The center insulator that comes with the A744 40 meter kit for the A3S is stronger than the insulator that comes with the A3S although it is still not solid Maybe cushcraft has them for sale. My guess is that the hollow insulator is not a problem at least not in california. Les, Hygain uses the same insulator for several of their antennas, and it can be a problem with all of them. Replacing it with a 'solid' insulator of some kind is one solution. I'm still hunting for a replacement for one for an 'R-7' (the only difference is in the length). Thought about using 'Delrin'(sp) or some other type of plexiglas/perspex, but haven't found a source yet. Good luck... 'Doc |
#4
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Thanks for that.
I took it that Cushcraft would have tested the antennas to destruction, so thought I was being over causious but have heard from others that the fiberglass breaks down after a while as it ages. I have managed to get hold of an original (or at least its on its way) If I an get a replacement I will the first chance I get. Will look at Delrin on the net and see what it is. Guess the insulator is not soild due to the extra it would cost in manufacture. Thanks again Les "Edward Lewis" wrote in message ... On Sun, 25 Apr 2004 07:58:12 -0500, 'Doc wrote: The center insulator that comes with the A744 40 meter kit for the A3S is stronger than the insulator that comes with the A3S although it is still not solid Maybe cushcraft has them for sale. My guess is that the hollow insulator is not a problem at least not in california. Les, Hygain uses the same insulator for several of their antennas, and it can be a problem with all of them. Replacing it with a 'solid' insulator of some kind is one solution. I'm still hunting for a replacement for one for an 'R-7' (the only difference is in the length). Thought about using 'Delrin'(sp) or some other type of plexiglas/perspex, but haven't found a source yet. Good luck... 'Doc |
#5
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Edward, I have 'good' days and 'bad' days. Seems like when I posted that one, it must'a been a really 'bad' day. Oh well. The 'R-7' is by Cushcraft (duh), but the rest of it was correct. 'Delrin'(sp?) comes in all shapes and sizes, just a form of plastic that handles RF and sun light well. Also a brand name, and I have no idea what the chemical composition is (other than a 47 letter name that I could care less about). If it's an insulator, the correct size, pretty strong, and a pretty shade of red, almost anything would work in place of the original fibreglass (I like red)... 'Doc |
#6
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'Doc wrote in message ...
Les, Hygain uses the same insulator for several of their antennas, and it can be a problem with all of them. Replacing it with a 'solid' insulator of some kind is one solution. I'm still hunting for a replacement for one for an 'R-7' (the only difference is in the length). Thought about using 'Delrin'(sp) or some other type of plexiglas/perspex, but haven't found a source yet. Good luck... 'Doc I've got a A4S which has the same thing on the driven element...I've often wondered what I'll do if that thing ever breaks...Guess the delrin rod is one idea. I've wondered about a wood dowel that is varnished as one solution...Or convert to boom grounded, and replace with aluminum...But then you'd have to add a matching device...MK |
#7
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cushcraft A3S Tribander HF beam
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#8
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I have a Di Pole that was in the same condition as the antenna you presently have.
Someone took it upon themselves to fix it with a type of fiberglass epoxy and some glass mat and some gel coat. The person that gave me the antenna assured me that it worked properly and it was adjustable for all 10 - 11 meters. Not really a screw driver type antenna, but it has a two nut adjustment at the base. I have a very old tube type 10 / 11 meters radio called a Siltronix 1011D - Comanche and the other day, after solving a problem with some used coax I bought - I was able to talk to a guy in Alabama with 60 watts output @ 1.2:1 SWR and he told me that my signal was 30 over S -9 and that my modulation was hot and that I needed to turn down my mic gain. I also talked to twp people on the chicken band after I put the antenna up 20 feet AGL and some local operators said I was 30 over S-9 and that my audio was really hot and I had the amplified Turner Plus 3 mic turned down half way and the radio turned down almost the whole way on the mic gain. So since the gel coat was deterioriated to the point of where the fiberglass was coming off in my hands, I took it upon myself to go down to the Dollar General Store and buy several can's of white paint. It was white or black - because that was all they had on stock. I had a can of Krylon universal paint and I applied one coat of RED paint between the coats of white - so as to be able to see when the top coat of white goes bad the red will show. I added a couple of ground radiators - since it had none and I put 3 independent ground stakes attached to the mast pipes and my output is very good. So I would think that if that antenna lasted that long the way it was, and if you were willing to do some work to modify it to make it stronger and put some resin over the antenna to protect the gel coat that it will probably last longer then you will. I was skeptical of putting up a dipole antenna 16 feet + tall in the mountains of Pennsylvania with all the high winds we have here with no guy wires on the 1 1/4 rigid conduit I used to attach it to the side of my garage - but the 35 - 55 mph winds we had this week was no match for the antenna and mast pipe - because it never even bent or contorted. |
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