Swr readings with and without amp

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original45
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Swr readings with and without amp

Post by original45 » 10 Jul 2019, 16:31

I have been having what I thought was antenna problems.
Just as I thought I was getting sorted I seem to have found a potential problem and need your advice.

If I set up my jackson 2 and on fm in ru mode output is 8 watts lowest setting . Swr will be reading 1.4 . Now if I adjust it to higher output or max which I think is roughly 24 watts this effects swr and jumps to nearly 3 in the red.
Heat sink seems to warm faster too.

Now if I run it low again 8 watts fm and put inline the rm kl 203 ,leaving a swr meter between both radio and amp I'm able get a low swr under 1,4 , key up and transmit amp pushes nearly 80 watts ish it's still v low in fact doesn't go up at all and may actually be lower .
Now this has me concerned and confused.
Is this normal , surely long overs would fry the back out .

I havnt tested this on my stryker 955 yet and that has even more fm output.

Is this normal.

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Mitch
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Re: Swr readings with and without amp

Post by Mitch » 10 Jul 2019, 20:10

Silly question but did you recalibrate the meter when you turned the power up? Also when testing the swr between rig and amp, the amp is the load not the aerial. Have you tried measuring the swr between amp and aerial? It is likely to go up then due to harmonics from the amp, could be the case for the rigs high power too, perhaps. I wouldn't want to put 8 watts into the amp though, bit too much for long overs, keep rig power lower and use the amp for power. Less output but a lot safer.
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original45
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Re: Swr readings with and without amp

Post by original45 » 10 Jul 2019, 20:35

For sure Mitch it was recalibrated. In end I set up two meters before and after amp.first measured swr before amp, second after amp power then swr .

Will test swr after amp tomorrow.

I need to set up a second antenna ,radio and check the stryker too.
I'm wondering if the antron still has a fault and is causing this issue .
Bit frustrating now as I'm not as technical as you guys and I don't want yo burn finals out.

For sure mitch I don't want to input 8 watts long into the amp, I generally only input 3/4 watts ,however I'm 're tracing steps to trace issues that could have caused high swr I had on antron 99 that made the sink warm on amp and radio.

Just seemed v v strange I can run 8 watts in to amp 70/80 out and see no increase in swr before amp reflecting, however no amp inline I turn up radios stock power to 20pluss and swr goes into red on meter.

Weird

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Mitch
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Re: Swr readings with and without amp

Post by Mitch » 11 Jul 2019, 19:36

If the swr is related to power into it, it could be faulty, have bad solder joints or failed components. Can it be disassembled to look inside? Here's what it looks like apart - http://www.radiomanual.info/schemi/ACC_ ... review.pdf
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ch25
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Re: Swr readings with and without amp

Post by ch25 » 11 Jul 2019, 20:47

First things first. How about measuring it on dummy load?
Chris
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original45
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Re: Swr readings with and without amp

Post by original45 » 11 Jul 2019, 22:52

Will look tomorrow gents, thanks.
Chris I just bought a dummy load ,will test when arrives .
Thanks both.

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