9ft Tank Whip (SWR)

General Mobile CB antenna advice and troubleshooting

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Nugsport
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Sun Jun 15, 2008 7:55 am

I all I was wondering if anyone could point me in the right direction I have a 9ft Tank Whip that has just started to hit the red on the swr meter, it was ok a few days ago, i have excellent ground plane i run a powerstick fixed roof mount which is grounded to bear metal, and also a 7" turbo mag, with the Orbitor attached i get a reading of 1:1.3 on the swr, as soon as i swap over to the tank whip its going into the red, I just find it hard to believe how it can be fine and then all of sudden its reflecting the power :? :?

any help would be greatly appreciated
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stampman
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Sun Jun 15, 2008 8:18 am

was it ok on the magmount before or the powerstick mount because the will alter between the differant mounts



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Nugsport
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Sun Jun 15, 2008 8:24 am

i did run a quick swr check when it was first attached to the mag about a week ago and it was about 1:1.5, i thought it was the powerstick causing the problem, i used to run it on the mag so i tried it on the magmount again just to be sure and both mounts show the high swr with the tank whip attached :( im thinking the antenna is at fault could this be possible? when i try my Orbitor on both mounts i get a low reading, well little higher on the mag as i would expect due to the ground difference, i sure am confused :| :cry:
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Steve
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stampman
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Mon Jun 16, 2008 8:17 am

just might need a bit triming off the tank whip to get the swr down if its higher on 40 than 1

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Nugsport
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Mon Jun 16, 2008 9:34 am

Thanks matey :) ill give it ago try and trim it in, the strange thing is though the reading on the swr stays in the exact same place in the red zone... throughout uk 1-40 and midblock 1-40 the needle dosn't move lol... it's a strange one it really is, your help is very much appreciated, i will let you know how i get on :D
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Steve
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stampman
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Mon Jun 16, 2008 3:14 pm

hang on if it dont move try taking the whip off the meter and seeing what the meter does then could be a faulty mag mount

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Mon Jun 16, 2008 4:42 pm

I removed the whip from both mounts and the meter nearly went off the scale so thats working lol, when i use my orbitor antenna its fine mate on both the magnetic mount and the powerstick roof mount, nice low readings, it only seems to plays up and goes into the red zone when i use my tank whip i have cut about 1" off the whip and still no improvement :( i have checked for continuity through the coax and the mounts and they are fine, no shorts, or anything, but then again it's perfect with the orbitor antenna. is it possible that i have a faulty meter or would you say its working fine from what i have tried and tested?
sorry to be a pain :(
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hotmetal1000
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Mon Jun 16, 2008 11:20 pm

It sounds like the only problem is with the tank whip.

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Tue Jun 17, 2008 7:41 am

would not think its a faulty meter does sound like a whip problem are all the connections clean on the whip and is the meter reading higher on 40 than 1



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Tue Jun 17, 2008 10:13 am

Thanks for the reply's :) ,

The meter does read slightly higher on ch40 uk, with my orbitor antenna i get 1:1.2 on ch1 and 1:1.4 on ch40, but with the tank whip the needle just sits on number 3 on the meter through all the channels there is no difference on ch1 or ch40, even on midblock it stays in the exact same place on 3. :?

Thanks once again for the help guy's :)

oh forgot to add yes all the connections are clean and free of corrosion etc.
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Tue Jun 17, 2008 7:43 pm

ok guy's think i have found the problem did a continuity check and left the coax accidnetly pluged into the cb, i was getting continuity between the mount 3/8 thred and the earth on the vehicle bodywork :o , i removed the coax from the cb and it was fine no continuity (no short) , up on closer inspection i tested the femal PL259 socket on the rear of the cb and the earth is shorting im getting a ressistance of 4.56Ω is this a big problem :?:
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stampman
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Wed Jun 18, 2008 7:43 am

yes take the plug off and resolder it should cure the problem


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Nugsport
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Wed Jun 18, 2008 11:43 am

wasn't sure if i was getting you confused with the actual PL259 plug and the female plug in the rear of the CB, i have taken some pics just to be sure :) i would think there is something wrong if both these are making continuity :? becuase when i try this on the coax i get no continuity same with the mount it's fine, just the plug on the rear is giving me a ressistance of 4.65Ω :?:
sorry to bother you people with all this.

Testing the plug
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Results on the meter
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Thanks
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Steve
DX The World
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stampman
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Wed Jun 18, 2008 1:43 pm

you will get a reading there as they generaly use capictors to link the signal to ground to remove interferance

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Nugsport
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Wed Jun 18, 2008 2:07 pm

oh ok :oops: well everything seems to be in good working order, think i will try another tank whip see if anything changes :)
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Steve
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