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High SWR Caused by too low of a PS?

Skuggi

Member
Feb 9, 2009
4
0
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Hey was just wondering if anyone knows if a High SWR can be caused by a weak power supply.

I have an old unit setup, still in great condition it was my uncles, and I found an old power supply that could be having issues and just not powerful enough (The display dims when I dead key). I put up an iMAX 2000 yesterday with new coax but the new power supply has yet to come in.

But when I'm keying or trying to do the SWR CAL it tops the dial and I can't get it to go down. I Rx Beautifully and it sounds like whoever's talking is right next to me. I can Tx LSB and hit a good distance away as I was talking with my boss a good 8 miles away like we were right next to each other. AM though I don't think anybody is even hearing me, and the SWR is all the way up.

I'm just wondering if this could be the PS being maybe 4a trying to push the radio, 75ft of coax and the iMAX. Or if there could be an antenna problem (But Rx and LSB are fine?) or if I'm gonna need a new radio for anything not side band.

... Just noticed, I somehow clicked the CB Services to post somehow... if anyone can move this to where it should be.
 
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Hey was just wondering if anyone knows if a High SWR can be caused by a weak power supply.

I have an old unit setup, still in great condition it was my uncles, and I found an old power supply that could be having issues and just not powerful enough (The display dims when I dead key). I put up an iMAX 2000 yesterday with new coax but the new power supply has yet to come in.

But when I'm keying or trying to do the SWR CAL it tops the dial and I can't get it to go down. I Rx Beautifully and it sounds like whoever's talking is right next to me. I can Tx LSB and hit a good distance away as I was talking with my boss a good 8 miles away like we were right next to each other. AM though I don't think anybody is even hearing me, and the SWR is all the way up.

I'm just wondering if this could be the PS being maybe 4a trying to push the radio, 75ft of coax and the iMAX. Or if there could be an antenna problem (But Rx and LSB are fine?) or if I'm gonna need a new radio for anything not side band.

... Just noticed, I somehow clicked the CB Services to post somehow... if anyone can move this to where it should be.

Thanks for moving me up the ladder a notch.
 
A few more details would be helpful, like radio, PSU, etc... I may be wrong but it almost sounds like you have the exact opposite going on, I would check for a bad connector or similar. Over the years, I've keyed more than one radio into shorted loads and one thing was always a constant, excessive current draw by the transmit. I suggest checking coaxial cable and connectors as a first step. Also if at all possible confirm the proper function of the Meter. Possibly you can find someone local to come over and help you, possibly bring another meter.
 
Short answer. No

SWR is all in the antenna system. Feedline + antenna

Power supply has nothing to do with it.

good luck

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Are you using the SWR meter built into the radio? That might be your problem, if so. Those get out of adjustment pretty easily, and they're not all that accurate to begin with. I would suggest hooking up an external SWR/Power meter and see what it says.
 
i agree the swr in the radio usually arent even close.even on new radios
youd be better off with a 30.00 swr meter at this point.and no a p.s wouildnt
cause a high swr.im surprised no one said this the location of your antenna
may affect your swrs.building and trees may affect swrs.make sure all connections
are tight on antenna and coax hookups.check pl259s with a dvm make sure there
good.
 
Sorry I haven't got on to reply sooner, and thanks for the replies.

I picked up a Radio Shack SWR meter to test with (I know I've read they're not the best, but I don't have a CB Shop and didn't want to wait on shipping.)

I'm getting a 2.5 SWR on the meter, the weird thing is it's showing me a power of 1500w?

I Have a modified HAM Rig that my uncle always had used up until he couldn't go down the stairs anymore so I'm pretty sure the unit isn't bad. The PS is a Vista IV.

In testing I was able to get a Tx out LSB about 20 miles away but it was faint. More locally about 6 miles away I had a guy on AM Rxing me Loud and Clear until the PS started heating up.
 
If you're using a "modified ham (not "HAM") rig", a four ampere power supply is only about one-sixth of what you need. I'm really surprised the PS fuse/breaker hasn't opened. Assuming, of course, that it has one.
 
Was able to get up and get some testing and got a dummy load to put on the coax. The coax checked out. I also got my Jetstream PS in and got in contact with a good radio guy. What it's looking at with the way the imax radiates is that I'm way too close to the roof. I'm about a foot away, when reading the instructions I didn't realize there would be a problem as it's a non metal roof and I'm over 9ft from the neighbors roof.

And yea, it's a Uniden HR2510. I'm actually just getting into radio, figured I'd go get a ham licence and such, wouldn't have even known it could do CB if it wasn't for my uncles notes.
 

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