| Author |
Message |
    
HIGH TECH REDNECK
| | Posted on Friday, November 09, 2001 - 9:45 pm: | 
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ok heres the problem i added an amp in my 99 s10 truck problem is when i turn on my amp i go from a 1.1-1.2 to a 2-3 swr!! but if i turn up the wattage on the radio to excede the 4 watt input the swrs come down for awhile to 1.5 then shoot back up when checking it again!! why? i have a emperor running into a super modulator then rg8x out to my antenna which is rated at 20000 watts so im sure it can handle a 100watts easy. the mounting is done by a clamp the holds my bedliner down. i made a metal bracket to come off the aluminum c clamp out of the bed 3 inches outside the bed where the antenna is mounted in the very back of the truck. i scraped some paint off where the clamp mountes under the bed rail so i think its getting a ground. what else to do....i am not going to change radio or amp i what these to work together as im not rich as i used to be. thanks for any advise. |
JYD
| | Posted on Saturday, November 10, 2001 - 10:40 am: |
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USE A 3 FOOT JUMPER AND I WOULD HAVE MY DEAD KEY ABOUT 2 WATTS. HOW BIG OF JUMPER AR YOU USING? |
Tech181
| | Posted on Saturday, November 10, 2001 - 9:45 pm: |
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High Tech,
Could be a lossy piece of coax in the midst. If everything else works out, try some new coax sections between the antenna and amp, and between the amp and the radio.
Steve
Tech181
Tech181@copperelectronics.com |
HIGH TECH REDNECK
| | Posted on Sunday, November 11, 2001 - 4:38 pm: |
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brand new rg8x 3 foot jump it hung a high swr at 9 foot jumper so went to 3 foot and it lowered it from 3 to like 2 to 1 but it really depends on my dead key into the amp. i have to dead key more then the four watt max input to lower the swr !? weird. brand new rg8x 18 foot out to antenna. if i just run the radio 1.1-1.2 soon as i turn amp on at 2 input the swr is 3 to 1 if i put 5 watts into the 4 watt input amp i get a 1.5 but it does stay at 1.5 if i drive a mile down road stop and check it again i end up increasing input wattage or decreasing it just a lil to get swrs to drop in again!! |
Tech181
| | Posted on Sunday, November 11, 2001 - 4:49 pm: |
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Do you have another amplifier you could try in place of the one your using now to see if you can duplicate the problem?
Steve
Tech181
Tech181@copperelectronics.com |
Warlock
| | Posted on Monday, November 12, 2001 - 5:40 am: |
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The TNT supermods are famous for swr problems to start with. Suggest selling it and get something different. |
HIGHTECH REDNECK
| | Posted on Monday, November 12, 2001 - 8:09 pm: |
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my texas star does same thing but if you put a dummy load on it it matches perfect . but reconnect it to an antenna and back to same problem. |
Warlock
| | Posted on Monday, November 12, 2001 - 9:22 pm: |
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Then you have poor antenna ground/counterpoise. What type antenna, mount, where's it mounted and how old is the coax. |
2SF2696
| | Posted on Monday, November 12, 2001 - 10:20 pm: |
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You guys are forgeting Harmonics. That will give you a false SWR everytime.
Phineas
2SF2696 |
Marconi
| | Posted on Saturday, November 17, 2001 - 11:15 am: |
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Redneck did the right thing checking the system with a dummy load. This would suggest that the antenna may be reacting to a mismatch, but because the problem is intermittent it is likely the mount is involved. Another thing to consider is, these radios are said to have a quirk of suddnely changing output power. Check that out also.
If it is possible check the radio, modulator, and the working line on another antenna with a different mount. A magnetic mount would be convient. |
Inspector
| | Posted on Saturday, November 17, 2001 - 5:12 pm: |
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Are you re-calibrating each time you change wattage? Also, do you have the SWR meter between the amp and the antenna...that's where it needs to be. |
HIGH TECH REDNECK
| | Posted on Saturday, November 17, 2001 - 8:30 pm: |
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well drilled 2 holes and lounted the antenna today to the bed rail by the tailgate great with no power. but if i still run my radio at 3 watts into the amp it shows 2.5 swr but when i put 6 watts into a 4 watt input amp it drops to 1.3!! and if i get it there and turn the truck off then come back an hour later turn truck on then check it back up to 2.5 til i adjust my rf power on radio to drop swr down. swr meter all 3 that ive tried...radio shack and 2 mfj models all show this problem. swr meter is after amp and to antenna. i was thinking of getting a ranger 2970 and seeing if a radio with built in amp will do the same or if it... wont have the external amp problem. but cash is short at moment you know. any other ideas?? my texas star also does same thing have to drive it at full input power or more to drop swr down. |
MrRF
| | Posted on Saturday, November 17, 2001 - 9:30 pm: |
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Sounds like either bad cable, harmonic/spurious emissions from the amp, or ground loops...Are the amp and radio grounded (or a better term, BONDED) to the vehicle frame. The DC power wires are not always a sufficient ground. I suggest heavily grounding the amp housing.
good luck,
MrRF |
Hamcber
| | Posted on Sunday, November 18, 2001 - 3:39 am: |
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This totally sounds like a case of splatter and/or high harmonics.
Put your radio and amp on a spectrum analyzer and see what it looks like. I'll bet there's a lot of lawn...
If you're anywhere near me, bring it over. |
HIGHTECH REDNECK
| | Posted on Sunday, November 18, 2001 - 1:42 pm: |
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no idea where you are ham cber in here in north carolina. thing is i tried changing radios amps the coax is new even put new 3 foot jumpers still doesnt change it. how would i get rid of harmonics anyway. amp is grounded thru a frame ground and radio is grounded to battery. ive never run into this problem before and its just pi..ing me why i cant seem to get it right. i tried a magnet mount on roof and it would not tune in at all but it tuned in on my last vehical perfect. maybe this truck just does like radios amd amps. thanks for any help |
Warlock
| | Posted on Monday, November 19, 2001 - 5:43 am: |
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You said you tried a magnet mount with the same results? On the roof? Try a Wilson 1000 magmt on the roof and be on your way. I GUARANTEE you will end your problems using the W1k mgmt on the roof and wire your amp's +/- to the battery with 8ga wire. Use the ground wire you ran to the frame to ground the case of the amp. |
Hamcber
| | Posted on Monday, November 19, 2001 - 11:07 am: |
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Warlock, you can't guarantee that will fix his problem since you don't really know what it is.
If the problem is harmonics and/or spurious emissions, either tuning or replacing bad components will likely fix it. Spurs come from poorly tuned or failing RF circuits. Sometimes, they even come from poorly designed circuits.
Most of the CB hacks that 'tune' CB radios do not own a spectrum analyzer and cannot possibly know if they are creating a problem or not. Spurs and harmonics sure make the watt meter look like you're putting out power, when in reality, you are putting very little of the transmitter's energy on the fundamental freq. |
Warlock
| | Posted on Monday, November 19, 2001 - 8:28 pm: |
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I can guarantee it with his Texas Star. I cannot with the TnT Super modulator. He said he had the exact symptoms with BOTH amps. The TnT's are dirty as pigpen. The TS's aren't the greatest, but typically don't have problems as such unless he's having ground/counterpoise problems which I highly suspect.
That is exactly why I made the recommendation I did. It will work with the Texas Star. It will work better even with the TnT.
High Tech, please get rid of that super mod. |
HIGHTECH REDNECK
| | Posted on Tuesday, November 20, 2001 - 6:59 pm: |
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well right now i decided not to run the amps ill run the radio til i either get a another wilson or i just get a rci 2970 with the built in power. i do need to check the radio with a analyzer but most techs dont have one...maybe why they arent an authorized repair place such as for my kenwood. ok thank you guys. |
Jyd
| | Posted on Sunday, December 30, 2001 - 8:35 pm: |
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well,the truck bedside is not the best place for it.get a 102 whip and 20 feet of coax mount it on your rear bumper its a better ground cause it is connected directly to the frame,also if your truck doors are open when you are testing swr it will be higher. i read this in wilson instruction manul also ever think about testing your swr with a different meter,try someone elses meter to. |
Bigbob
| | Posted on Thursday, January 17, 2002 - 9:42 pm: |
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TRY this high tech,check the tension of the sockets of your so239s on your box,if they are loose they will cause variable swr.This happened to me,I pinched them closer together and cured it. |
Honkytonkman593
| | Posted on Friday, January 18, 2002 - 4:49 pm: |
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ill tell him i talk to him on and off. its funny i have the same problem in my other truck at 2 watts in to a 4 watt max amp my swr is 3 to 1 but as i get to 4 watts or even 6 watts in exceeding the input of amp swr goes to 1.2 like it does when amp is off!! just weird. so i just run the amp at full wattage all the time. and expect it to go some day but til then im loud!! maybe its just chevys!! |
