| Author |
Message |
    
Rid0617
Junior Member
Username: Rid0617
Post Number: 16
Registered: 12-2005
| | Posted on Wednesday, April 12, 2006 - 3:39 am: | 
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I have a 10 meter dipole (16 feet 5 inches) with a 1:1 balun. Can this antenna be tuned to transmit on 20 meters with a reasonable MFJ tuner or do I need to add copper wire to bring it up to 20 meters? If I do that and buy the MFJ tuner will the 4:1 balun in the tuner cause a problem with the 1:1 balun on the dipole? Thank you. Not very smart on the dipole/balun issue. Normal throw verticals up in the air.
Ron
KB4YKJ |
Bruce
Senior Member
Username: Bruce
Post Number: 3740
Registered: 9-2003
| | Posted on Wednesday, April 12, 2006 - 6:17 am: |
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yes it can my MFJ tuner will do that however if you add wire to each end and bring it down to 14.250 it will work much better that just using the tuner alone. |
Zukeeny
New member
Username: Zukeeny
Post Number: 6
Registered: 10-2007
| | Posted on Sunday, August 24, 2008 - 7:09 am: |
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hello, not sure if I am in the right place to ask this (I am usually not), I have been given 4 different lengths of RG8/U base antenna coax. none of the four pieces are long enough to run from the location of my radio to where I am placing the antenna, my question is if I put a couple of 259 and a double female 239 and hook two of the pieces of coax together will that work ok, or will I lose to much performance by doin that. Thank You Very Much Bill |
Tech858
Moderator
Username: Tech858
Post Number: 164
Registered: 10-2007
| | Posted on Sunday, August 24, 2008 - 7:49 am: |
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Zukeeny
Joining the 2 pieces with the double female will work fine so long as you seal up the join properly and don't get any moisture in there , as for losses there are a few factors that can make a difference ,the quality of the antenna couplings my preference would be to use N-type male and female instead of 2 x 259 with double female as a lot less loss , how long are the pieces of rg-8 , has the coax you are going to use been used before and stored in a dry place , just a few to take into consideration , but if you are just wantin on air for the moment as I said it will work ok but better with some new coax . 
Tech858/Jim
CEF#0858 ~ CEF HAM#0230
CVC#0116 ~ MM0TXO
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Captian_radio
Intermediate Member
Username: Captian_radio
Post Number: 421
Registered: 9-2004
| | Posted on Sunday, August 24, 2008 - 9:38 am: |
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Now this reminds me that I have a few hundred feet on 1/2 heliax stored in the shed, will come in handy soon when its time to put up the vhf stuff and old surplus N connectors to boot.
Bob CEF451/VE1CZ
Robert L. Spicer The days of radio are just beginning!
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Tech833
Moderator
Username: Tech833
Post Number: 1690
Registered: 8-2002
| | Posted on Sunday, August 24, 2008 - 11:32 am: |
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The loss of a PL-259 to an SO-238 barrel to another PL-259 will be in the 0.6 dB range. Assuming this is regular 95% shield RG-8 we are talking about, and not LMR-400 or the Copper equivalent, then it would be about the same loss as an additional 64 feet of coax cable.
In other words, if you put 5 watts into the coupling, you would get 4.36 watts out (0.598 dB attenuation).
Let's say you have 100 total feet of cable, two 50 foot runs coupled together in the manner suggested above. If you put 5 watts in, you get 3.51 watts out the other end. If you ran a straight 100 foot long piece of cable without the coupling, and you put 5 watts in, you would get 4.03 watts out the other end. |
Fishbones182
New member
Username: Fishbones182
Post Number: 7
Registered: 4-2009
| | Posted on Friday, May 01, 2009 - 4:05 pm: |
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As far as the dipole antenna for 10 meters and wanting to use it on 20 meters it depends. You can use the antenna on 20 sure but if it coax fed the line loss on the feed line will be extremely high. You would be better off using a 20 meter dipole on 10 meters and youd get more gain out of the antenna as well because it would be multiple wave lengths on 10 meters. Now if you really want a dipole to work say from 80 meters through 10 meters put up about 110 feet of number 12 wire center fed with lets say 450 ohm twin lead and it will work fantastic. Any balanced feed line will work great the dipole im describing is called a doublet dipole |
