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swr problem

F

fasteddie

Member
Jul 20, 2009
56
0
16
42
upstate ny
Still working out the bugs of my new linear install new at running extra power. Question is swr betwean radio and amplifier is 1.3 to 1 wich i figure is fine, problem is betwean amp and antena with amp off swr is1.1 to 1, when I switch the amp on low (variable power amp) swr is 1.1 to 1. The problem is the ferther i turn up the amp the higher the swrs get "off the chart". Have everything grounded. good power fead plenty of amps. My rig is a galaxy dx 949 peaked and tuned i run a six digit frequency counter,Willson 5000 perminent mount, and a worldwide mf 440 veriable power 1 feading 4 advertised to push from 440 watts to 850 depending on where knob is. all is connected with belden 9913f7 cable.:headbang
 

fasteddie said:
Still working out the bugs of my new linear install new at running extra power. Question is swr betwean radio and amplifier is 1.3 to 1 wich i figure is fine, problem is betwean amp and antena with amp off swr is1.1 to 1, when I switch the amp on low (variable power amp) swr is 1.1 to 1. The problem is the ferther i turn up the amp the higher the swrs get "off the chart". Have everything grounded. good power fead plenty of amps. My rig is a galaxy dx 949 peaked and tuned i run a six digit frequency counter,Willson 5000 perminent mount, and a worldwide mf 440 veriable power 1 feading 4 advertised to push from 440 watts to 850 depending on where knob is. all is connected with belden 9913f7 cable.:headbang
Click to expand...
You'll have to reset your meters swr calibration for different power levels, the meter is not smart enough to do it for itself.

You should find the same readings at any power level when you do that.
 
I don't think I'd worry about the size of a groundplane very much, but I think I would recheck the tune on that antenna just to make sure it's what it should be. The only way I know to do that with only an SWR meter is by changing the length of the feed line to see if it causes any change in SWR. If it does cause -any- change in SWR, then the antenna is NOT tuned correctly. You've found your problem. If SWR doesn't change, then I'd look at the amplifier, there may be something 'not right' with it.
- 'Doc
 
what i don't understand is with the amp out of picture it runs flat swr and low it runs flat so that would tell me the antena is tuned right? how would the tune change just by turrning up the power? and where would i run the extra coax betwean amp and antenn? also is this for test only i'v heard changeing coax langth just maskes the problem.
 
fasteddie said:
what i don't understand is with the amp out of picture it runs flat swr and low it runs flat so that would tell me the antena is tuned right? how would the tune change just by turrning up the power? and where would i run the extra coax betwean amp and antenn? also is this for test only i'v heard changeing coax langth just maskes the problem.
Click to expand...
You've added a large impedance bump and the meter sees that so you may try tuning the antenna with the amp inline, but not transmitting.
 
"also is this for test only i'v heard changeing coax langth just maskes the problem."

Yes, it's just a test. If changing the length of coax does change the SWR, then the antenna isn't right. OR... if the antenna is right, then it means that the amplifier's output impedance changes with the power level. That's not right either.
Put that addition to the feed line's length in place of the amplifier. That ought'a do it. Got an extra jumper laying around??
- 'Doc
 
ADDED SOME COAX DID NOT MAKE A DIFFERENCE ALSO NOTICED IF I RUN AMP LOW SWR ARE AT 1.3 TO 1 AND AFTER TALKING AMP HEATS UP SWRS RAISE. IF I TURN THE VARIABLE KNOB AND CALIBRATE THE METER THE SWRS ARE OFF THE CHART THE AMP IS BRAND NEW RADIO IS NEW PEAKED AND TUNED FROM COPPER ELECTRONICS NEW ANTENA AND NEW CABLE. IF I LEAV THE AMP LOW AND IT HEATS UP WONT GO OVER 2.0 TO 1 ON SWR BUTT I WOULD LIKE TO BE ABLE TO TURN IT UP
 
Best advice I can give you is to stop using that amplifier until you solve the problem. There definitely is a problem, and if you continue to run that amplifier with it acting like that, it will destroy it's self. Nothing done so far is a -good- indication of where the problem is. But all indications, so far, certainly point toward the amplifier.
Something I just realized is that you haven't said what your antenna is. What is it? That can certainly be important in a couple of ways.
- 'Doc

(Or if you did say, then I've missed it somewhere.)
 
I hope you are checking the SWR in a large parking lot w/o any cars around - or in a large open space. Objects around the vehicle will make a difference when checking SWR - too. Especially when so much power is being applied.

Other than that, making sure all of you connections are sound. It could also be that the amp itself is having an internal problem, and may need to be taken to a shop for some adjustments.
 
im pretty sure this isnt the problem but more curious is how much deadkey/carrier
are ya using to drive the amp.also if ya can try another amp if have a extra one or if ya can get one from a local.cause if the swr stays low then its the amp
 
willson 5000 perminent mount solid in center of roof. the radio is stock tuned but tunned, has external rf power knobe (galaxy 949) i run it all the way down seams to run the cleanest i think it is around 2 watts i think may be a little more. also never hade problem with swr meter before butt it is a radio shack meter says it's rated for 2,000 watts.
 
fasteddie said:
willson 5000 perminent mount solid in center of roof. the radio is stock tuned but tunned, has external rf power knobe (galaxy 949) i run it all the way down seams to run the cleanest i think it is around 2 watts i think may be a little more. also never hade problem with swr meter before butt it is a radio shack meter says it's rated for 2,000 watts.
Click to expand...

How much carrier does that 1x4 produce with a 2 watt drive? One more thing you could check, wilsons have been known to be infiltrated by water so you might unscrew the antenna and give it a shake to see it this is the case.
 

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