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Pyrwitner1
Junior Member
Username: Pyrwitner1

Post Number: 16
Registered: 8-2005
Posted on Saturday, July 15, 2006 - 10:31 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I got a small problem. I recently installed a palomar 225 in my truck with a cobra 29 with a 102 inch whip installed in the inner bed wall of the bed.The problem im haveing is when i kick it on high power the antenna light comes on and the swr goes nuts. Iam thinking its a problem with the coax ,its got a pl259 and spade connectors on the antenna its the rg58 .So if anyone can gvie me in ideas other then replcaing the coax which i plan to do,please let me know .Also i am wonder what kind of power i should be seeing out of this amp i got it given to me with the radio ?the radio dks@4.
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Motor_doctor
New member
Username: Motor_doctor

Post Number: 9
Registered: 12-2005
Posted on Saturday, July 15, 2006 - 10:56 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

pyrwitner1 are you using a inline meter?
do not trust the one built into the radio
it is way off, at least the one i have is
charliec
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Bc910
Advanced Member
Username: Bc910

Post Number: 741
Registered: 7-2004


Posted on Saturday, July 15, 2006 - 11:08 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Pyrwitner1
First I'll answer your last question:
That amp driven in to a dummy load should be at or around 100-150 PEP.
Second, I will tell you to first try re-positioning the antenna
Think of an antenna this way-your whip is the positive and the fround (body of your truck) is negetive in a battery, or power supply etc. If you think about it that way with one exception, the positive (whip) radiate it's power rather than just traveling through it. When you touch a positive wire to a negetive wire, bad things happen. Immagine the possitive wire can spark even if it is just CLOSE to negetive but not touching!!! That is what happens when whips are installed in the way you have described. Your ground plain is interfereing with the radial. At best this will couse directional activity and poor transmit. At worst it will couse terrible SWR readings. When you add power into the mix, well it gets worse. Remember the analagy? Your 12 volt wire can't be close 'couse it is radiating it's power, so you have to spread your ground and + apart, immagine it was 120, or 240, etc. They would have to get spread further. At this point your probably lost completely or saying "EUREKA"! Either way I know your wondering why I can't spell and my post is extrodinaraly long...IM TIRED !!! :-)
Any way, The best place for an anttenna on a truck is at the very rear of the cab with the mount right on top so that the base of the antenna is above any part of the truck. This may NOT be the cause of your problem, but no matter what it WILL help!
My second idea (depending on where the SWR meter is located-you didn't say) is biasing in the amp. which should be a simple fix, try different length jumpers from the radio to the amp 2' 3' 6' etc.
RG58 is FINE for low wattage like you are running, I personaly prefer mini 8 but realy there is no difference to speak of. There are much better coax'es (coax'es? Is that how you say it?) out there but they start getting real think and real stiff real quick and can be very difficult when mobile. Again RG58 should be just fine.
But replacing the coax probably isn't a bad idea if it is getting old.
OK that is my long winded wierd post for the day, hope it helped! IM GOING TO BED NOW!!! :-)
BC
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Road_warrior
Senior Member
Username: Road_warrior

Post Number: 1756
Registered: 7-2004


Posted on Sunday, July 16, 2006 - 12:11 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

If Rg58 is that real thin coax. It's not
recommended to be used with any amp.
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Pyrwitner1
Junior Member
Username: Pyrwitner1

Post Number: 17
Registered: 8-2005
Posted on Sunday, July 16, 2006 - 5:56 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

OK gentlemen thanks and i think road is closer to the problem itis the thin stuff and to top it off i got it from rat shack .I am ordering some mini 8 from here and hoping it will fix the problem.The onlt time i have a problem is on high its acting like its getting hot then acting up,because it takes a minute or two for the light to come on .Also yes i have a bird cross needle meter its old but still on the money.
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Hotwire
Senior Member
Username: Hotwire

Post Number: 1551
Registered: 1-2005
Posted on Sunday, July 16, 2006 - 10:11 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Pyrwitner, Yes for the love of 11 meter get rid of that radio shack coax.
Just over the last 2 weeks I have been comparing a 102 inch whip against a Predator 10K. I installed the whip with a ball mount and spring high up on the rear passenger side fender and the coax is lug connected to the mount. Some may disagree but I strongly believe that the 4 inch spring plus the 2 inch width of the ball mount is extremely neccesary for the proper installation of the 102 inch whip. 108 inches is actually the correct electrical length for a full size qaurter wave whip resonant to cb. My swr is solid 1.1 though the whole band at any power level! I experimented without the spring and swr went up to 1.3 to 1.5 across the band. Actually ok cause nobody can hear the difference over the radio. Also the antenna is not next to any of the vehicle body at all. If your antenna is you should move it away. This is a very important fact for the full size whip. Most likely your swr is high period. Its when you add more power you get higher reflect levels since your antenna is near the metal body. That and low cost amps seem to cause poor swr readings. Try your new coax without the amp and hope swr is at least 1.5 if possible with your mount. Adding the amp is not gonna change the antenna swr. Just fyi I have been using rg213 coax in the mobile for a while now. It definately made a noticable difference over the basic mini8. good luck

Oh and to anyone interested. At least for dx work the Predator wins over the whip I compared to it. Now if I was able to install the 102 inch whip on top the car like the Predator.....well you know the rest of this story. The whip was just to darn directional for DX.
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Pyrwitner1
Junior Member
Username: Pyrwitner1

Post Number: 18
Registered: 8-2005
Posted on Sunday, July 16, 2006 - 10:17 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

You know hot that might be part of the problem because it is close to the bed rail as it goes up ,infact if i didnt have a piece of pvc on it ittouch the rail and it probally is reflecting off of the insdie of the bed. but im not going to put another hole in the bed of the truck or the outside on the fender .My swr is pretty good now like 1.4 to 1.8 across the band.
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22caliber
New member
Username: 22caliber

Post Number: 1
Registered: 7-2010
Posted on Wednesday, July 28, 2010 - 4:45 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

i just purchased a small palomar 80 for my 4 wheeler.first time i hooked it up it blew the factory 10 amp fuse.i tried better ground straight to the battery red and black only running about three feet of 14 gauge wire after the third fuse blew i just gave up.anyone have any suggestions.i sure could use the answer.thanks. 22 caliber
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Tech808
Moderator
Username: Tech808

Post Number: 17779
Registered: 8-2002


Posted on Wednesday, July 28, 2010 - 6:15 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

22caliber,

Your radio may have blown the amp with too high of an input.

With a small 80 watt amp you would only want an input power of about 1 or 2 watts.

Was the Amp new or used?
Lon~Tech808
N9CEF
CEF#808

Radio Enthusiast!


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