| Author |
Message |
    
Thehobo
Member
Username: Thehobo
Post Number: 51
Registered: 2-2004
| | Posted on Sunday, January 15, 2006 - 12:32 pm: | 
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ok, have the 6 ele. star coming and was wondering if i could put the coil of coax rite after the pl connector of the gamma match to help make a choke to keep rf from coming back on the shield to the shack??? plan on putting at least 4 loops of about 4 inches at each gamma match!! will that help, and is it going to be enough loops for what i think im trying to do??? it will be on both vert. and horz. and probley taped to the boom rite at the gamma match!! thanks to any input or more helpful hints..
thehobo
274150 am.
monitor ch. |
Bruce
Senior Member
Username: Bruce
Post Number: 3408
Registered: 9-2003
| | Posted on Sunday, January 15, 2006 - 1:52 pm: |
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The coax choke trick works on any antenna.....
Even a Jogunn .... |
Marconi
Advanced Member
Username: Marconi
Post Number: 516
Registered: 11-2001
| | Posted on Sunday, January 15, 2006 - 3:36 pm: |
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I disagree with Bruce on this one. A choke should do something but I have never been able to see them do anything. I just don't think they are effective enough at doing that job.
However, hobo why don't you let us know how your setup works out. I recall Chad had a thread about all of this and even showed some pictures of one working and doing it well. Do a search on Chad and maybe it will turn up for a reference. |
Thehobo
Member
Username: Thehobo
Post Number: 52
Registered: 2-2004
| | Posted on Monday, January 16, 2006 - 8:13 am: |
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it mite be awhile till i get the antenna in the air, but i will give a report on what ever i do??
ive got a few more parts coming for the tower so i can get the rotor in side the tower?? as heavy as the jo gunn is, i thought this wood be best?? even thought about mounting the jo gunn rite on top of the rotor to help take the side to side sway out of it?? but do have a cone nose piece coming!! thanks for the input..
thehobo
274150 am. monitor ch. |
2ec837
Member
Username: 2ec837
Post Number: 98
Registered: 12-2001
| | Posted on Thursday, January 19, 2006 - 12:25 pm: |
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"plan on putting at least 4 loops of about 4 inches at each gamma match!!" |
Thehobo
Member
Username: Thehobo
Post Number: 53
Registered: 2-2004
| | Posted on Thursday, January 19, 2006 - 1:01 pm: |
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talked to jo gunn, and they dont recomend it?? so ill try it the way the directions tell me how to put it together?? thanks..
thehobo
274150 am.
monitor ch. |
Marconi
Advanced Member
Username: Marconi
Post Number: 541
Registered: 11-2001
| | Posted on Thursday, January 19, 2006 - 1:49 pm: |
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If a choke is correct it will not affect the signal or audio at all. I'm not sure that 4 loops is enough, but I'm not sure that this type of choke will do what it is supposed to do in this setup or not. I have asked Bruce a question about how to tell if one is needed, maybe he will pitch in with a little more info.
Personally I have never been able to tell if they work or not. I understand that even these yagis, like the Joe Gunn, probably need one to help decouple the feed line from affecting the beams pattern, but others say that gammas fix that and others say that nothing will really fix that and others say that chokes will not fix this, and others say don't worry about the problem you probably can't fix it anyway.
It is just a choice I suppose, but I would like for Bruce to tell us how he knows when an antenna needs a balun or choke. Come on Bruce, give us some more info here. You do claim they work, right? |
Thehobo
Member
Username: Thehobo
Post Number: 54
Registered: 2-2004
| | Posted on Friday, January 20, 2006 - 2:18 pm: |
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i believe one of the reasons they didnt recomend it at the gamma match, is they and in there docs, state that the vertical wire goes from the match and taped on top of the boom to were it goes down on the boom to mast clamp?? also the horizonel is taped the same way, only on the side of the boom?? they did say that as the coax was leaving the boom, i could do the loop thing there?? to me thats defeating the purpose of the choke??? being as im about to put some money into this thing, im going to do it there way first?? they did build the thing!!! so ill go from there!! i did order the latest matches they make for it, as the old ones had some cracks in the insulater plastic which i didnt think was to good?? if this works as it should?., it should be a pretty good antenna for my use?? got all crossed that all will go rite!! to youall, thanks for the input on this project..
thehobo
274150 am.
monitor ch. |
Thehobo
Member
Username: Thehobo
Post Number: 55
Registered: 2-2004
| | Posted on Saturday, January 21, 2006 - 8:14 am: |
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the match is in the uprite position in front of the sender!! on the horazonial gammamatch, its under the sender as some others are!! hope im not miss leading some of yaall in my descriptions of whats going on?? only the coax runs dow the top of the boom to the mast mount as the horizonal does on the side of the boom?? as i said above, ill follow there docs, == this time, == lol.. agin thanks toall..
thehobo
274150 am.
monitor ch. |
Bruce
Senior Member
Username: Bruce
Post Number: 3436
Registered: 9-2003
| | Posted on Saturday, January 21, 2006 - 11:33 am: |
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ok i thought it was on the botom of the vetical driven elm. Marconi i though the match was on the bottom ...... |
Marconi
Advanced Member
Username: Marconi
Post Number: 547
Registered: 11-2001
| | Posted on Saturday, January 21, 2006 - 12:01 pm: |
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Are you thinking that the gamma on one of the angled down radials is wrong, like is should not be there? If so, I'm surprised that you don't know that is the gamma that drives the horizontal side of the Jo Gunn antenna. |
Marconi
Advanced Member
Username: Marconi
Post Number: 548
Registered: 11-2001
| | Posted on Saturday, January 21, 2006 - 1:20 pm: |
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Ok, I just misunderstood what you were getting at. I didn't think you were really off base, but your statement did confuse me.
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Bruce
Senior Member
Username: Bruce
Post Number: 3445
Registered: 9-2003
| | Posted on Saturday, January 21, 2006 - 2:16 pm: |
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Ok NOW i know what is big! so ill try and make it smaller ..... |
Al_lafon
Intermediate Member
Username: Al_lafon
Post Number: 172
Registered: 3-2005
| | Posted on Saturday, January 21, 2006 - 8:56 pm: |
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A balum can be used with most antennas used on CB
but you have to insulate the antenna from the mast some how. i use pvc pipe just a little bigger than my mast cut it down the sides.Then hose clamp it over the mast now mount your antenna on this now the balum will do its thing
but don't forget you still need to ground your
coax as close to real ground as you can.You can
also do this with Beam antennas use this on the boom of the antenna if your antenna is a big one
then get 2 big nylon bolts at a hobbie shop to
pin your boom with this keep it from turning off
horizonel or vertical they go all the way thu to
the boom to mast mouting plate. a word here about
gama matchs i like the t match best of all i moded a maco 4 to a t match .
73s AL
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Tech808
Moderator
Username: Tech808
Post Number: 9045
Registered: 8-2002
| | Posted on Sunday, January 22, 2006 - 9:24 am: |
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Thehobo,
Assemble you antenna per the assembly instructions.
Then if you find you have a problem with anything then you can adddress that problem.
I personally would not worry about adding anything that may not be needed if you have no problems.
Good Luck with your installation and keep us posted on your results. 
Lon
Tech808
CEF808
N9OSN |
Marconi
Advanced Member
Username: Marconi
Post Number: 551
Registered: 11-2001
| | Posted on Sunday, January 22, 2006 - 10:17 am: |
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I agree with Al lafon about insulating the antenna from ground.
When I had my last 4 element yagi up, before the storms in the Gulf this past summer, I always felt that it showed a little skew in pattern off one side of the beam. It was an old HyGain antenna that used a gamma on the horizontal side. If I ever put it up again, I will try some way of trying to balance the feed point using a blaun or something in order to see if the skewing will be fixed. I think I know for a fact with that beam, if I detuned it to improve the rejection as apposed to the gain, it seems like the skewing problem goes away or at least gets better. So I guess the more gain you have the more skewing you have from the affects of common mode currents in a beam. So I believe this probably needs to be fixed when possible instead of just ignoring it.
Thanks for the discussion,
Eddie |
Thehobo
Member
Username: Thehobo
Post Number: 56
Registered: 2-2004
| | Posted on Sunday, January 22, 2006 - 6:24 pm: |
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thanks to one and all, ill try to keep yaall up to date on the install!! im at the point of cementing in guy post and awaiting new parts.. agin thanks..
thehobo
274150 am. monitor ch. |
