Antenna Question for KX1
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Hi All
I have been playing with my KX1 in the back yard the last week or so and found that about 26ft of wire in the hot side of the bnc connector and about the same to the cold side gets me a good match with the built in ATU on 40,30,20m Now if I use the same wires but add 20ft of coax between the radio and these wires I find it very hard to get a match on any band, do I need to use a balun at the end of the coax? Any thoughts Paul M0BMN -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.5.1/327 - Release Date: 28/04/2006 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hi Paul,
Without modeling your antenna, I don't know what the feedpoint impedances are, but it's a good thing that you can match them with the KX-1. The 20 foot length of coax is transforming the impedance to something outside the range of your KX-1, and a balun wouldn't help unless (perhaps) it was also an impedance transformer. Hope this answers your question. 73, ed - k9ew _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by m0bmn
Paul
The loss in poorly matched coax can be very high, you might consider using a length of 300 Ohm ribbon cable instead. You will need a balun at the KX1 end of the ribbon. With my K1 across 40/30/20/15 I find a 66 foot top (33' each side) with 32 foot of ribbon tunes with the KAT1 in my K1. I understand the tuning range of the KX1 ATU is even less than that fitted to a K1, so you might have to play around with the length of ribbon to get a satisfactory match. The advantage is you can get the dipole part of the antenna a reasonable height with a fishing pole or similar support. 73 Dave, G4AON K1 # 1154 K2 # 1892 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by m0bmn
Paul,
A balun may or may not help. and in any case, a balun or no balun is not the answer to your situation - the 20 ft of coax is acting like an impedance transformer, and without a thorough analysis of your antenna and feedline system, it is difficult to say what would help. Perhaps some experimentation is in order - add a 4:1 balun and see what happens, simlarly try a 1:1 balun, try changing the length of the parallel feedline, and try changing the length of the coax. All these things will influence the results, as will changing the length of the antenna wires. If you do not have adequate instrumentation to analyze the system, then a bit of old fashioned 'cut and try' may be the way to properly answer your questions - in any case, keep notes of what happens so you will know which way to go when making future changes. When you find something that works, rejoice and let us know, perhaps some of us can give you some info relating to why it works. 73, Don W3FPR > -----Original Message----- > > I have been playing with my KX1 in the back yard the last week or so and > found that about 26ft of wire in the hot side of the bnc > connector and about > the same to the cold side gets me a good match with the built in ATU on > 40,30,20m > > Now if I use the same wires but add 20ft of coax between the > radio and these > wires I find it very hard to get a match on any band, do I need to use a > balun at the end of the coax? > > Any thoughts > > Paul > > M0BMN > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Antenna Question for KX1
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Try taking a big fat toroid from somewhere and looping your coax
through that about 15 times at the antenna end and see how that works for you. Alternately, put a bunch of clip-on beads on the coax at the antenna end and try that. Alternately, try lengthening the antenna on the 'hot' side as the coax braid may be acting as the ground side. Not saying I know, just saying, Try. 73 de Alex NS6Y. On Apr 30, 2006, at 5:49 PM, Don Wilhelm wrote: > Paul, > > A balun may or may not help. and in any case, a balun or no balun is > not the > answer to your situation - the 20 ft of coax is acting like an > impedance > transformer, and without a thorough analysis of your antenna and > feedline > system, it is difficult to say what would help. Perhaps some > experimentation is in order - add a 4:1 balun and see what happens, > simlarly > try a 1:1 balun, try changing the length of the parallel feedline, and > try > changing the length of the coax. All these things will influence the > results, as will changing the length of the antenna wires. If you do > not > have adequate instrumentation to analyze the system, then a bit of old > fashioned 'cut and try' may be the way to properly answer your > questions - > in any case, keep notes of what happens so you will know which way to > go > when making future changes. When you find something that works, > rejoice and > let us know, perhaps some of us can give you some info relating to why > it > works. > > 73, > Don W3FPR > >> -----Original Message----- >> >> I have been playing with my KX1 in the back yard the last week or so >> and >> found that about 26ft of wire in the hot side of the bnc >> connector and about >> the same to the cold side gets me a good match with the built in ATU >> on >> 40,30,20m >> >> Now if I use the same wires but add 20ft of coax between the >> radio and these >> wires I find it very hard to get a match on any band, do I need to >> use a >> balun at the end of the coax? >> >> Any thoughts >> >> Paul >> >> M0BMN >> >> > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by m0bmn
Paul
You might like to check out this antenna idea on the Adventure Radio Society web site: http://www.arsqrp.com/ars/pages/back_issues/2006_text/0506_text/N7XJa.html Looks good to me, and it's been used on 40/30/20 with a KX1. 73 Dave, G4AON _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by m0bmn
Is the coax ok?
Add or remove length from antenna. Guessing interaction between coax & antenna. This should demonstrate that pretty quick. What is the impedance range of auto tuner? "Don Wilhelm" <[hidden email]> wrote: __________ >Paul, > >A balun may or may not help. and in any case, a balun or no balun is not the >answer to your situation - the 20 ft of coax is acting like an impedance >transformer, and without a thorough analysis of your antenna and feedline >system, it is difficult to say what would help. Perhaps some >experimentation is in order - add a 4:1 balun and see what happens, simlarly >try a 1:1 balun, try changing the length of the parallel feedline, and try >changing the length of the coax. All these things will influence the >results, as will changing the length of the antenna wires. If you do not >have adequate instrumentation to analyze the system, then a bit of old >fashioned 'cut and try' may be the way to properly answer your questions - >in any case, keep notes of what happens so you will know which way to go >when making future changes. When you find something that works, rejoice and >let us know, perhaps some of us can give you some info relating to why it >works. > >73, >Don W3FPR > >> -----Original Message----- >> >> I have been playing with my KX1 in the back yard the last week or so and >> found that about 26ft of wire in the hot side of the bnc >> connector and about >> the same to the cold side gets me a good match with the built in ATU on >> 40,30,20m >> >> Now if I use the same wires but add 20ft of coax between the >> radio and these >> wires I find it very hard to get a match on any band, do I need to use a >> balun at the end of the coax? >> >> Any thoughts >> >> Paul >> >> M0BMN >> >> > >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com >. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by m0bmn
In message <[hidden email]>, Paul Webb
<[hidden email]> writes >Hi All > > > >I have been playing with my KX1 in the back yard the last week or so and >found that about 26ft of wire in the hot side of the bnc connector and about >the same to the cold side gets me a good match with the built in ATU on >40,30,20m > >Now if I use the same wires but add 20ft of coax between the radio and these >wires I find it very hard to get a match on any band, do I need to use a >balun at the end of the coax? > >Any thoughts > >Paul Hi Paul, I believe you are on a hiding to nothing attempting to reproduce the results via a length of coax cable. Remember those initial results were obtained with the ATU connected directly to the antenna. Everything after the ATU is effectively the antenna and is likely to radiate, including the coax. Adding a balun will do absolutely nothing except to change the electrical antenna length (where the antenna in this case is the coax and the original wires), your coax will still radiate and you are likely to get poor results. With this sort of antenna the ATU must *always* be at the antenna end of the feeder, whether that be directly after the ATU in the KX1 as in your initial trials, or at the antenna end of the 20 foot of coax as you attempted later. The only exception to this is when the antenna presents an electrical quarter wave or odd multiple thereof. In those cases, no ATU is necessary. Trev G3ZYY -- Trevor Day UKSMG #217 www.uksmg.org _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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