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SWR jump with amp
Posted: Monday 17th Apr 2006, 4:25
by Mrhardluck
I may have this question in the wrong forum. I got my radio peaked and tuned for a palomar 250 elite. My first amp so I put it in with a SWR/WATT meter combo so I could check SWR before I powered up amp. My SWR is 1.1 after a adjustment or two. When I turn on the amp and key the mic the SWR pegs out on the meter. With the amp off the SWR is 1.1 when I key. Is this normal, SWR will always peg out when you have an amp on?
Re: SWR jump with amp
Posted: Tuesday 25th Apr 2006, 14:57
by Restring
Mrhardluck wrote:I may have this question in the wrong forum. I got my radio peaked and tuned for a palomar 250 elite. My first amp so I put it in with a SWR/WATT meter combo so I could check SWR before I powered up amp. My SWR is 1.1 after a adjustment or two. When I turn on the amp and key the mic the SWR pegs out on the meter. With the amp off the SWR is 1.1 when I key. Is this normal, SWR will always peg out when you have an amp on?
Did you retune the SWR meter after turning on the amp??
Posted: Sunday 14th May 2006, 16:59
by nomadradio
Like MrSixString says, you have to readjust the "Cal" knob for the higher power level before you can read SWR with the amplifier on.
And if the SWR is still high once you've reset the Cal knob, it means that your amplifier is putting out extra harmonic frequencies. Since most of them contain NO harmonic filtering at all, it's not that unusual a thing to see. The antenna is not tuned for those frequencies, and most of the wattage at those frequencies is reflected back from the antenna, driving up the SWR reading.
73
Posted: Thursday 15th Jun 2006, 15:29
by Dazz
A parasitic Oscillation outside the antennas resonance would do this 4 sure.
Plain harmonics such as the second and third, fifth etc. would have to be massive to do that.
You need a tunable RF sniffer to find out what is goin' on or a receiver and turn down RF gain.
Best of luck, dazz in auz.