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#1
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I installed a CB in my Jeep Rubicon for use when my buddies and I go trail
riding. I mounted a *ahem* 48" Radio Shack fiberglass whip on a right angle antenna mount directly to the rear bumper. I ran a 20' Radio Shack 50 ohm cable from the antenna to the transmitter mounted under the seat (Cobra 75 WX ST). Power is supplied by a 4 ga. wire directly from the battery. I scraped off paint under one of the seat mounting brackets and bolted the wire to that to get a good ground. The problem I'm having is calibrating the SWR meter. When key and hold down the mic, I turn the meter's calibration knob all the way to the right and the needle is still short of the calibration mark. Any suggestions would be greatly appreciated. Rob Kulp |
#2
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In , "Rob"
wrote: I installed a CB in my Jeep Rubicon for use when my buddies and I go trail riding. I mounted a *ahem* 48" Radio Shack fiberglass whip on a right angle antenna mount directly to the rear bumper. I ran a 20' Radio Shack 50 ohm cable from the antenna to the transmitter mounted under the seat (Cobra 75 WX ST). Power is supplied by a 4 ga. wire directly from the battery. I scraped off paint under one of the seat mounting brackets and bolted the wire to that to get a good ground. The problem I'm having is calibrating the SWR meter. When key and hold down the mic, I turn the meter's calibration knob all the way to the right and the needle is still short of the calibration mark. Any suggestions would be greatly appreciated. Rob Kulp Could be lots of things. First, check the radio and antenna on a friend's vehicle to make sure they work. Check the coax to make sure there isn't a short from the center conductor to the shield. Check the entire length of the coax to see if there are any nicks, crimps or sharp bends. If so, or if you are using foam coax (RG-xx/F), throw it away and get some good stuff. Wind your excess coax in a figure-8, not a loop. Keep your ground lead as short as possible. Make sure the antenna mount isn't shorted. Check your SWR meter to make sure you have it set for the correct range. The meter could be bad, so test your installation with a different meter. Check your DC voltage at the radio when you key up -- if the voltage drops you might have a weak connection somewhere. If all that fails to reveal the problem, seek a local expert. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#3
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![]() "Rob" wrote in message om... I installed a CB in my Jeep Rubicon for use when my buddies and I go trail riding. I mounted a *ahem* 48" Radio Shack fiberglass whip on a right angle antenna mount directly to the rear bumper. I ran a 20' Radio Shack 50 ohm cable from the antenna to the transmitter mounted under the seat (Cobra 75 WX ST). Power is supplied by a 4 ga. wire directly from the battery. I scraped off paint under one of the seat mounting brackets and bolted the wire to that to get a good ground. The problem I'm having is calibrating the SWR meter. When key and hold down the mic, I turn the meter's calibration knob all the way to the right and the needle is still short of the calibration mark. Any suggestions would be greatly appreciated. Rob Kulp Have you hooked up an actual swr meter? If so, what was it's reading? Landshark -- Hard things are put in our way, not to stop us, but to call out our courage and strength. |
#4
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On Tue, 30 Mar 2004 01:07:55 GMT, "Rob" wrote:
I installed a CB in my Jeep Rubicon for use when my buddies and I go trail riding. I mounted a *ahem* 48" Radio Shack fiberglass whip on a right angle antenna mount directly to the rear bumper. I ran a 20' Radio Shack 50 ohm cable from the antenna to the transmitter mounted under the seat (Cobra 75 WX ST). Power is supplied by a 4 ga. wire directly from the battery. I scraped off paint under one of the seat mounting brackets and bolted the wire to that to get a good ground. The problem I'm having is calibrating the SWR meter. When key and hold down the mic, I turn the meter's calibration knob all the way to the right and the needle is still short of the calibration mark. Any suggestions would be greatly appreciated. If an SWR meter will not calibrate, there are 3 common reasons for this (and a whole list of uncommon ones). The first is an obvious lack of transmitter power. If your radio isn't putting out at least a watt or 2, chances are you won't be able to calibrate the meter. The second is a radical fault in the antenna/feedline system. If the cable or antenna mount is shorted, it can prevent the meter from calibrating. One way to check this is to switch to the SWR position. If the meter stays at the same point, you have a short. The third common reason is a simple one. Is the meter hooked up backwards? If you reverse the input and output connections, the meter will not work properly, and you are actually trying to calibrate on the reflected power (Which should be low). Again, a check for this would be to switch to the SWR position. If the meter now pegs hard, chances are you have it backwards. Oh, and I just thought of a 4th reason. Are you sure you're on the calibrate position? Dave "Sandbagger" http://home.ptd.net/~n3cvj |
#5
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On Tue, 30 Mar 2004 01:07:55 GMT, "Rob" wrote:
I installed a CB in my Jeep Rubicon for use when my buddies and I go trail riding. I mounted a *ahem* 48" Radio Shack fiberglass whip on a right angle antenna mount directly to the rear bumper. I ran a 20' Radio Shack 50 ohm cable from the antenna to the transmitter mounted under the seat (Cobra 75 WX ST). Power is supplied by a 4 ga. wire directly from the battery. I scraped off paint under one of the seat mounting brackets and bolted the wire to that to get a good ground. The problem I'm having is calibrating the SWR meter. When key and hold down the mic, I turn the meter's calibration knob all the way to the right and the needle is still short of the calibration mark. Any suggestions would be greatly appreciated. Rob Kulp First check what Frank and Dave suggested, then try this: (hopefully your antenna is one of Radio Shacks adjustable ones) 1. Find out which channel gives you the lowest forward calibration reading (1 or 40) 2. Note that reading 3. flip the switch to check the reverse reading. 4. Note that reading. 5. Change to the channel that gave you the highest forward calibration reading. 6. Adjust the reading to same level as step 2. 7. flip the switch to check the reverse reading. 8. This will give you a "relative" SWR reading. 9. Depending on which channel gave you the lowest "relative" reading: If your lowest reading was on channel 1, your antenna is too long. If your lowest reading was on channel 40, your antenna is too short. Adjust your antenna. |
#6
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On Tue, 30 Mar 2004 13:48:06 GMT, Lancer wrote:
On Tue, 30 Mar 2004 01:07:55 GMT, "Rob" wrote: I installed a CB in my Jeep Rubicon for use when my buddies and I go trail riding. I mounted a *ahem* 48" Radio Shack fiberglass whip on a right angle antenna mount directly to the rear bumper. I ran a 20' Radio Shack 50 ohm cable from the antenna to the transmitter mounted under the seat (Cobra 75 WX ST). Power is supplied by a 4 ga. wire directly from the battery. I scraped off paint under one of the seat mounting brackets and bolted the wire to that to get a good ground. The problem I'm having is calibrating the SWR meter. When key and hold down the mic, I turn the meter's calibration knob all the way to the right and the needle is still short of the calibration mark. Any suggestions would be greatly appreciated. Rob Kulp First check what Frank and Dave suggested, then try this: (hopefully your antenna is one of Radio Shacks adjustable ones) 1. Find out which channel gives you the lowest forward calibration reading (1 or 40) 2. Note that reading 3. flip the switch to check the reverse reading. 4. Note that reading. 5. Change to the channel that gave you the highest forward calibration reading. 6. Adjust the reading to same level as step 2. 7. flip the switch to check the reverse reading. 8. This will give you a "relative" SWR reading. 9. Depending on which channel gave you the lowest "relative" reading: If your lowest reading was on channel 1, your antenna is too long. If your lowest reading was on channel 40, your antenna is too short. Adjust your antenna. And if this works as described, when you are done, take your radio to a local tech to determine why your power out is so low.... Dave "Sandbagger" http://home.ptd.net/~n3cvj |
#7
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I hate to admit it, but the meter was hooked up backwards.
Thank you for the help. On another note, on channel 1 my SWR is 2 and on channel 40 it's 3. The antenna is a 48" Fiberglass whip from Radio Shack and is adjustable. I'm guessing that I need to shorten the antenna? Thanks again, Rob Kulp "Dave Hall" wrote in message ... On Tue, 30 Mar 2004 01:07:55 GMT, "Rob" wrote: I installed a CB in my Jeep Rubicon for use when my buddies and I go trail riding. I mounted a *ahem* 48" Radio Shack fiberglass whip on a right angle antenna mount directly to the rear bumper. I ran a 20' Radio Shack 50 ohm cable from the antenna to the transmitter mounted under the seat (Cobra 75 WX ST). Power is supplied by a 4 ga. wire directly from the battery. I scraped off paint under one of the seat mounting brackets and bolted the wire to that to get a good ground. The problem I'm having is calibrating the SWR meter. When key and hold down the mic, I turn the meter's calibration knob all the way to the right and the needle is still short of the calibration mark. Any suggestions would be greatly appreciated. If an SWR meter will not calibrate, there are 3 common reasons for this (and a whole list of uncommon ones). The first is an obvious lack of transmitter power. If your radio isn't putting out at least a watt or 2, chances are you won't be able to calibrate the meter. The second is a radical fault in the antenna/feedline system. If the cable or antenna mount is shorted, it can prevent the meter from calibrating. One way to check this is to switch to the SWR position. If the meter stays at the same point, you have a short. The third common reason is a simple one. Is the meter hooked up backwards? If you reverse the input and output connections, the meter will not work properly, and you are actually trying to calibrate on the reflected power (Which should be low). Again, a check for this would be to switch to the SWR position. If the meter now pegs hard, chances are you have it backwards. Oh, and I just thought of a 4th reason. Are you sure you're on the calibrate position? Dave "Sandbagger" http://home.ptd.net/~n3cvj |
#8
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Don't buy Rat Shack junk!
Dave! On Tue, 30 Mar 2004 01:07:55 GMT, "Rob" wrote: I installed a CB in my Jeep Rubicon for use when my buddies and I go trail riding. I mounted a *ahem* 48" Radio Shack fiberglass whip on a right angle antenna mount directly to the rear bumper. I ran a 20' Radio Shack 50 ohm cable from the antenna to the transmitter mounted under the seat (Cobra 75 WX ST). Power is supplied by a 4 ga. wire directly from the battery. I scraped off paint under one of the seat mounting brackets and bolted the wire to that to get a good ground. The problem I'm having is calibrating the SWR meter. When key and hold down the mic, I turn the meter's calibration knob all the way to the right and the needle is still short of the calibration mark. Any suggestions would be greatly appreciated. Rob Kulp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#9
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On Tue, 30 Mar 2004 15:20:20 -0500, Dave or Debby
wrote: Don't buy Rat Shack junk! Dave! You mean don't buy any of Daves junk. You crow about your 25 years of experience, but how many times have you answered someones question for help? Why would anyone believe a word you say? |
#10
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On Tue, 30 Mar 2004 12:23:39 -0500, Dave Hall
wrote: On Tue, 30 Mar 2004 13:48:06 GMT, Lancer wrote: On Tue, 30 Mar 2004 01:07:55 GMT, "Rob" wrote: I installed a CB in my Jeep Rubicon for use when my buddies and I go trail riding. I mounted a *ahem* 48" Radio Shack fiberglass whip on a right angle antenna mount directly to the rear bumper. I ran a 20' Radio Shack 50 ohm cable from the antenna to the transmitter mounted under the seat (Cobra 75 WX ST). Power is supplied by a 4 ga. wire directly from the battery. I scraped off paint under one of the seat mounting brackets and bolted the wire to that to get a good ground. The problem I'm having is calibrating the SWR meter. When key and hold down the mic, I turn the meter's calibration knob all the way to the right and the needle is still short of the calibration mark. Any suggestions would be greatly appreciated. Rob Kulp First check what Frank and Dave suggested, then try this: (hopefully your antenna is one of Radio Shacks adjustable ones) 1. Find out which channel gives you the lowest forward calibration reading (1 or 40) 2. Note that reading 3. flip the switch to check the reverse reading. 4. Note that reading. 5. Change to the channel that gave you the highest forward calibration reading. 6. Adjust the reading to same level as step 2. 7. flip the switch to check the reverse reading. 8. This will give you a "relative" SWR reading. 9. Depending on which channel gave you the lowest "relative" reading: If your lowest reading was on channel 1, your antenna is too long. If your lowest reading was on channel 40, your antenna is too short. Adjust your antenna. And if this works as described, when you are done, take your radio to a local tech to determine why your power out is so low.... Dave "Sandbagger" A really mismatched antenna could cause a low forward reading on an SWR meter. Anyway, he did figure out that he had his meter backwards. |
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