WTF SWR

[jazzsinger]

That fantasy power you reference is predominant on 11m mostly. As far as hf radios and the power meters I have slways found then to be as good ad any external meter of decent quality. Not a gigadollar meter mind you but an average decent meter.

yep, i don't disagree, fantasy power does predominate on 11m, well the part of it that isn't harmonically radiating all over the spectrum anyway.

i think you have to be realistic in your expectations of 99.99% of any power meters, even decent ones tend to be around +/- 5% at best, but then there's very few genuine cases where people actually need better accuracy than that, maybe if your trying to get fcc certification, but for hobby radio of any kind its overkill.

its far more important knowing your signal is clean than it is knowing if it is accurate to the nearest watt, but i'm sure there will be no shortage who disagree.

if anyone can tell the difference between a 95w signal, a 100w signal and a 105w signal which is plus or minus five percent i'd be very impressed.

 

[Ratfink]

I am getting frustrated. I bonded my truck last night and my SWR went off. I retuned my antenna but my radio meter is making me nervous.

I'll try to make this as non-confusing as I can. My extenal meter is showing a hair under 1.2 on Ch 1 & 40. When my external is taken away my radio's SWR meter shows 1.6 on ch 1 and 1.8 on ch 40. I click over to PWR and it shows a 20W DK. I hook up the external meter again and it shows the same SWR as it did earlier, 1.2 on Ch 1 & 40. The radio's meter drops its SWR reading to 1.5 on Ch 1 & 19 & 40. I click over to the PWR and it reads 32W DK (like it should). Why does my SWR seem to rise without the external meter hooked up? I know that the internal meter isn't accurate, but the power meter seems to see the difference as well. Without the external meter hooked up, the radio smells like its getting hot. Even the talkback is quieter than normal, just like as if I'd turned down the variable power. What the hell?

I checked SWR in a field, no nearby objects, all doors closed, the allen wrench wasn't left in the set screws either.
I am throwing that Wilson in the basement and putting up a 102" antenna. That ball mount can't get here fast enough. Freakin Wilson is probably made by barjan these days, like everything else, and turned to junk. I hope its the antenna system being faulty and not something with the radio. I can't afford to send this thing out again.

Sounds like a bad coax end or jumper. Check your ends I got brand new coax ends and they were sloppy as hell and gave me fits. With your meter out of line wiggle all your coax ends and see if your radios receive changes at all just because coax is new doesn't mean it's good. You may have a so-239 with a sloppy center pin. Forget the swr meter on your radio. It's only there for looks only a total newbie would rely on it With most radios these days have QC issues .

 

[Ratfink]

Like some have said an antenna analyzer can be you friend to get you in the ball park and a bird 43 is your life line when fine tuning your reflect

 

[nobody]

FWIW I have a base station CB that does the same thing in regards to the internal / external SWR meter reading. The internal meter shows a slightly higher reading than the external meter. With the external meter in line they read the same thing. How ever my mobile radio, in the truck, reads the same rather or not an external meter is in line with it.
Did the other problems begin after you boned the body panels? Every time I fooled around trying to "improve" the grounding for the antenna it made things worse on my vehicles. \
Did I read your post correctly? Are you permanently mounting a 102" whip on the roof? Some times I wonder if the metal in roof of my truck is sturdy enough for my 5/8th wave 2 meter (NMO mount) antenna when I hit stuff with it. I like the 102 for the CB but have always had them either mounted to the center, rear of a tool box or the side rail of the truck and have had great results with them.

 

[Captain Kilowatt]

I still say some more knowledge of transmission line theory is needed. An SWR meter will read differently when placed in different places along the length of a transmission line when it is connected to an antenna that is not a perfect 50 ohms. You can prove that by inserting a length of line to effectively lengthen the line and taking another reading of the SWR. Guaranteed it will be different.

 

[Marconi]

I still say some more knowledge of transmission line theory is needed. An SWR meter will read differently when placed in different places along the length of a transmission line when it is connected to an antenna that is not a perfect 50 ohms. You can prove that by inserting a length of line to effectively lengthen the line and taking another reading of the SWR. Guaranteed it will be different.

CK I think you're right.

In reading this thread you can already see all the CBBS buzz words being used here and there. I also doubt your simple suggestion to test for the possibility of feed line transformation will even be considered by most...much less being tried.

I will also note that an analyzer does not deal any better with an antenna system that shows symptoms of transmission line transformation than an inline meter will. Understanding what the analyzer functions suggest, besides the SWR and maybe looking for a R value near 50 ohms, can give you some clues however, but it cannot ignore those line affects if they are present between the meter and the feed point. Only way to really know what the condition is at the feed point is to put the analyzer directly at the feed point, and that don't happen too often.

As the problem is described here, it does not sound like a physical problem with the feed line to me, or I think Roadrage would have reported an intermittent, or a dead short indication with his SWR meter, in the radio or not.

You're right, a better understanding is what is necessary.