| Author |
Message |
    
Wildrat
Intermediate Member
Username: Wildrat
Post Number: 243
Registered: 12-2003
| | Posted on Wednesday, November 09, 2005 - 9:22 am: | 
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If I were to build one of these, what would be the best freq. to build it for?
Wildrat
CEF674 |
Tech808
Moderator
Username: Tech808
Post Number: 8310
Registered: 8-2002
| | Posted on Wednesday, November 09, 2005 - 10:31 am: |
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Wildrat,
THIS QUESTION IS EASY TO ANSWER!
CHANNEL 13 / 27.115
The OFFICIAL CEF Radio Club Stand By Channel / Frequency 
Lon
Tech808
CEF808
N9OSN |
Bruce
Senior Member
Username: Bruce
Post Number: 3202
Registered: 9-2003
| | Posted on Wednesday, November 09, 2005 - 10:33 am: |
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a YAGI ( YAGI-UDA ARRAY ) can be built for any frequency. they have been built from a few hunderd KHZ to 5 GHZ but the most uses will be in the 7 - 450 MHZ range.
BELOW 21 mhz you will rarely see more than 3 elem and above 144 mhz ( 2 meters ) under 4 elems and antennas of 40 elems have been built and tested on 1232 mhz and 2500 mhz. |
Bruce
Senior Member
Username: Bruce
Post Number: 3203
Registered: 9-2003
| | Posted on Wednesday, November 09, 2005 - 10:41 am: |
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Here are some REAL gain numbers
http://www.nlrs.org/AntennaGain/2004Au.pdf |
Wildrat
Intermediate Member
Username: Wildrat
Post Number: 247
Registered: 12-2003
| | Posted on Wednesday, November 09, 2005 - 11:33 am: |
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Why did I not think of 13, probably because I am not yakking on that freq. yet.
Thanks Bruce for the info, I am going there now to ck it out. I already downloaded a calculator for figuring out the the different lengths of the pieces. I have also been to that signal engineering site amd read their material. Now like everything else I just need todo it.
Wildrat
CEF674 |
Wildrat
Intermediate Member
Username: Wildrat
Post Number: 248
Registered: 12-2003
| | Posted on Wednesday, November 09, 2005 - 4:47 pm: |
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Bruce I looked at the gain numbers on the different home brew Yagi's and they very, is that because of the difference in workmanship and quality of parts used to build them, plus of course the equipment and freq's used?
Wildrat
CEF674 |
Bruce
Senior Member
Username: Bruce
Post Number: 3206
Registered: 9-2003
| | Posted on Wednesday, November 09, 2005 - 7:42 pm: |
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correct You MUST build them RIGHT!
Now at CB you have lots of room to error at CB a 1/2 wave elem is about 110 inches and you have 1% error on a short YAGI before it goes down hill. So at cb you can be off 1% and 1% of 110 inch is 1.1 INCHES at 1296 mhz a 1/2 wave elem is 4 inches and you have .04 inch to play with!
Matching is important too the 2 most common are GAME and BETA matches here is a sample of a beta match beam......
http://www.hy-gain.com/man/pdf/LJ-105CA.pdf
Many books on antennas are out there ARRL and RSGB among them as well as the BILL ORR antenna books.
Lots of info out there
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Wildrat
Intermediate Member
Username: Wildrat
Post Number: 252
Registered: 12-2003
| | Posted on Thursday, November 10, 2005 - 10:12 am: |
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Hey thats great, instructions to put my home brew together.I like the idea with the rope inside the elements to cut down on vibration.
Thank You Bruce!
Mark
CEF674 |
Bruce
Senior Member
Username: Bruce
Post Number: 3209
Registered: 9-2003
| | Posted on Thursday, November 10, 2005 - 5:50 pm: |
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OOPS
NOT GAME and BETA it's GAMA and BETA
Here is a gama match
http://www.arrowantennas.com/inst/igif/i52-4t-4.gif |
Wildrat
Intermediate Member
Username: Wildrat
Post Number: 257
Registered: 12-2003
| | Posted on Thursday, November 10, 2005 - 7:39 pm: |
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I knew what you were saying.
Wildrat |
