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#1
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Does an 88 ft. doublet have any advantage over a conventional 67 ft.
doublet? In either case, feedline would be approx. 50 ft. of 450 Ohm ladder line to a 4:1 current balun, then a short length of coax into the shack. My usual band of choice is 40, but I'd like to become more active on 20 and 30. -- Vy 73 de Bert WA2SI FISTS #9384 QRP ARCI #11782 |
#2
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On Sun, 26 Sep 2004 13:22:15 GMT, "Bert Craig"
wrote: Does an 88 ft. doublet have any advantage over a conventional 67 ft. doublet? In either case, feedline would be approx. 50 ft. of 450 Ohm ladder line to a 4:1 current balun, then a short length of coax into the shack. My usual band of choice is 40, but I'd like to become more active on 20 and 30. Hi Bert, Short answer: No. [could be Yes] Long answer: Yes. [could be No] More details are needed to lengthen the short answer or shorten the long answer. Are you pointed in the right direction? A longer antenna can invalidate that. Can you load the antenna? A longer antenna can invalidate that. Going to higher bands makes these questions even more meaningful. Advice: Leave it alone, or put it up higher. 73's Richard Clark, KB7QHC |
#3
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Bert Craig wrote:
Does an 88 ft. doublet have any advantage over a conventional 67 ft. doublet? In either case, feedline would be approx. 50 ft. of 450 Ohm ladder line to a 4:1 current balun, then a short length of coax into the shack. My usual band of choice is 40, but I'd like to become more active on 20 and 30. Hi Burt, W4RNl , Cebik gives a good write up on this and some Ideas on other antennas as will ( you'll need a PDF reader though) You can find his article at http://www.cebik.com/fdim/fdim9.pdf Hope this is of some help. 73 Dave KC1DI |
#4
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"Richard Clark" wrote in message
... On Sun, 26 Sep 2004 13:22:15 GMT, "Bert Craig" wrote: Does an 88 ft. doublet have any advantage over a conventional 67 ft. doublet? In either case, feedline would be approx. 50 ft. of 450 Ohm ladder line to a 4:1 current balun, then a short length of coax into the shack. My usual band of choice is 40, but I'd like to become more active on 20 and 30. Hi Bert, Short answer: No. [could be Yes] Long answer: Yes. [could be No] More details are needed to lengthen the short answer or shorten the long answer. Are you pointed in the right direction? A longer antenna can invalidate that. Can you load the antenna? A longer antenna can invalidate that. Going to higher bands makes these questions even more meaningful. Advice: Leave it alone, or put it up higher. 73's Richard Clark, KB7QHC Advice taken, thanks Richard. :-) -- Vy 73 de Bert WA2SI FISTS #9384 QRP ARCI #11782 |
#5
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"KC1DI" wrote in message
... Bert Craig wrote: Does an 88 ft. doublet have any advantage over a conventional 67 ft. doublet? In either case, feedline would be approx. 50 ft. of 450 Ohm ladder line to a 4:1 current balun, then a short length of coax into the shack. My usual band of choice is 40, but I'd like to become more active on 20 and 30. Hi Burt, W4RNl , Cebik gives a good write up on this and some Ideas on other antennas as will ( you'll need a PDF reader though) You can find his article at http://www.cebik.com/fdim/fdim9.pdf Hope this is of some help. 73 Dave KC1DI Sure is, DAve. I now have the page saved offline, thanks so much. :-) -- Vy 73 de Bert WA2SI FISTS #9384 QRP ARCI #11782 |
#6
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"Bert Craig" wrote in message .net...
Does an 88 ft. doublet have any advantage over a conventional 67 ft. doublet? It depends! One big consideration is "on which band"? On 80 meters, the 88 footer will do a better job than the 67 footer because the feedpoint Z is higher and less reactive. If you can get to 132 feet, things get really good on 80 - but that's a lot of space to find. The 88 footer will theoretically have some gain broadside to the wire on 40 through 20 meters because it's longer than a half wave but shorter than a 1.28 wave (think of two 5/8 wave verticals back to back..) Above 20 you theoretically get a cloverleaf pattern. W4RNL explains it better than I can but you already know that... In either case, feedline would be approx. 50 ft. of 450 Ohm ladder line to a 4:1 current balun, then a short length of coax into the shack. That's the rub - feeding the beast. Model the thing with Reg Edwards' DIPOLE3 freeware and see what you can expect on the various bands. My usual band of choice is 40, but I'd like to become more active on 20 and 30. If you can get the feed figured out, it might be worth doing. Be aware that the gain isn't more than a few dB, and an inefficient feed system can eat a lot of it up. Ideally, you'd eliminate the balun and run straight to a balanced tuner. All depends on your house/shack situation. Some family members take a dim view of new holes in new walls - can't understand why... 73 de Jim, N2EY |
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