Swr issue after peak and tune..

BammBamm said:

I had some odd noise in my receive like a varying receive volume so I made the drive to a recommended shop and had him look at my 980ssb. He found a cold solder point and while there I had him tune my radio to my TS 250..He used a bird meter a tone generator and a scope and showed 2.5 watt DK swinging 9 and 10 watts on SSB. After tuning, it showed 1.5 swinging to about 9 and 13 on SSB. My SWR was 1.3 on 1 and 1.4 on 40 but after tune, I'm at 1.7 on 1 and 2.4 on 40...tried adjusting antenna with it directly to radio and can't get better than 1.9 on each end and 1.6 on 20! Using meter in radio (it's all I have). Using diagnostics it says antenna is O.K. but I'm terrified of burning up my radio not to mention the thought of even using my amp. Did the radio shop tune or not tune something right? I'm using a Wilson 1000 antenna. Thanks.

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Well, there unknown variables here! I don't know what this tech did either inside the radio or inside the amp if anything at all that resembled proper procedure? So the first thing I'm wondering about is if you are talking about SSB when you say it showed 1.5 DK as there should be no DK on SSB unless the balance is off or there is a lot of background noise. Anyway, we would need to know what was messed with in the final section of the radio because if this change is the result of attempting to tune a radio to an amp it often will result in some level of mistuning the radio which could also result in a change of readings on the Wilson. I'm speculating. Now in the world of amps, it's a rare that the input section of "CB amps" will be very good but if that is true then the input section of that amp is the place to change that and that will more often result in a little less output, not more. For that reason tunning a radio to the amp by most techs results in the radio being mis-tuned. This is a lot of speculation but based on what you describe and my not being there to see it for myself. If anyone can show me the error of my thoughts on this please don't hesitate my ego is nestled smack on top of 2 strong shoulders and even after 50 years of doing this I can be wrong or even forget.

OldTech

Don't trust the meter in the radio....

coil spreader

Road Squawker said:

coil spreader

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Yes, this is most likely what was done as it would or could have an adverse effect on the match he was used to seeing before the so-called "tune to amp" procedure was done. Usually, the average "I think I know how to do this" kind of guy will look for an increase in the output of the amp and not actually consider anything else hence an increase in output result justifies the means but the means result in pi network mismatch that in turn will show a different reading than before, and on and on and on it goes.

OldTech

I would get a cheap meter and a short jumper and put it on the amp output. I have a cheap workman and it redlines at 3:1 and I am under the impression that anywhere below that won't hurt. Maybe amps are more critical? I don't know. Then put the meter between the radio and amp. If you are still below 3:1 then i would say that you are good.

Unless I am totally wrong, maybe someone else can shine some light on this.

ShadeTreeMechanic said:

I would get a cheap meter and a short jumper and put it on the amp output. I have a cheap workman and it redlines at 3:1 and I am under the impression that anywhere below that won't hurt. Maybe amps are more critical? I don't know. Then put the meter between the radio and amp. If you are still below 3:1 then i would say that you are good.

Unless I am totally wrong, maybe someone else can shine some light on this.

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Are you sure you don't mean 1.3 :1?

Do not trust the meter in the radio. I tuned a friends radio and it showed better with the swr on the radio than with a external.

I would take both the radio and the amp back to this guy and tell him what is happening and to make it right. If he spread the coils; then tell him to put them back to OEM shape. If he did spread the coils; then after he fixes it - never take anything to him again. He should know better.

You now have SWR re-flux syndrome. Harmonics are running amok in your radio.

BammBamm said:

Easy guys...he didn't spread the coils or clip anything and only adjusted the pots. I did go back to the shop and took in radio, all checked good except that on his meter on the bench it showed a 1.5 on swr and the radio meter showed 2.4..When he raised the AM deadkey back to 3.7 watts it matched his meter on swr...tuned it back to 1.5 watts dk on am and bought a external meter and went to my truck and found that internal shows 2.3 on each end and external meter shows 1.2 . Would like to know if others have seen this.

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sounds like you need a good ground or something in your car is causing noise

kaos513 said:

sounds like you need a good ground or something in your car is causing noise

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From what I read, this was repeated on the bench but the external swr meter showed a different reading until he raised the DK to 3.7 watts and then it matched.
I'm not familiar with the 980 and I'm not sure why simply lowering your dead key would change the swr reading in the radio unless it won't calibrate far enough with the lower DK to get a good reading? I have no clue.

BammBamm said:

I had some odd noise in my recieve like a varying recieve volume so I made the drive to a recommended shop and had him look at my 980ssb. He found a cold solder point and while there I had him tune my radio to my TS 250..He used a bird meter a tone generator and a scope and showed 2.5 watt DK swinging 9 and 10 watts on SSB..After tuning it showed 1.5 swinging to about 9 and 13 on SSB. My SWR was 1.3 on 1 and 1.4 on 40 but after tune I'm at 1.7 on 1 and 2.4 on 40...tried adjusting antenna with it directly to radio and can't get better than 1.9 on each end and 1.6 on 20! Using meter in radio (it's all I have). Using diagnostics it says antenna is O.K. but I'm terrified of burning up my radio not to mention the thought of even using my amp..Did the radio shop tune or not tune something right? I'm using a Wilson 1000 antenna. Thanks.

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its the texas star then.

BammBamm said:

Easy guys...he didn't spread the coils or clip anything and only adjusted the pots. I did go back to the shop and took in radio, all checked good except that on his meter on the bench it showed a 1.5 on swr and the radio meter showed 2.4..When he raised the AM deadkey back to 3.7 watts it matched his meter on swr...tuned it back to 1.5 watts dk on am and bought a external meter and went to my truck and found that internal shows 2.3 on each end and external meter shows 1.2 . Would like to know if others have seen this.

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Never trusted or used the radio SWR meter on every radio I have ever had. Always use an external meter or an MFJ antenna analyzer.