Why does my radios built in SWR meter only work if...

[High_Speed]

Why is it that if I just have my antenna connected directly to my radio, my radios SWR meter will always read 1.0 on all channels? Yet if I hook my external meter up to the radio, then the radios built in meter reads pretty similar readings to what my external meter reads (1.05 on ch 1 and 1.5 on ch 40)?

I'm really confused as to why I have to hook an external meter to the radio before the built in meter works? What's going on here?

[Bombero]

Hey...

Using an external meter is just for your protection in case your internal meter isn't calibrated.

If yours is matching the external meter...go for it and disconnect the external meter.

Bombero

[High_Speed]

Hey...

Using an external meter is just for your protection in case your internal meter isn't calibrated.

If yours is matching the external meter...go for it and disconnect the external meter.

Bombero

What I'm confused on, though, is that if I disconnect the external meter, no matter what I do then, the radio's SWR meter will always just read 1.0 on all channels. Why does it only work if the external meter is hooked up?

[MDYoungblood]

Get a barrel connector and leave the jumper coax inline to see if you get a different reading. Normally when you add something inline the radio's SWR meter only sees what the coax and item added. Find someone with an antenna analyzer and see what the antenna is really reading, you'll be surprised.

3's

Greg

[Deleted User 14541]

The reading on the radio may be different because now it has an impedance bump (the meter) between it and the antenna. Common mode current is usually present in most mobile installs. When you start changing coax lengths adding jumpers, adding meters and moving things around the swr reading can also change.

Some will tell you the external meter is just more accurate. It may or may not be from one case to another but which ever you choose to believe your stuff is working just fine. Not a thing wrong with the readings you have.

[High_Speed]

I'm sorry, I'm still confused. I understand that adding the meter and 3' jumper in the mix is going to change the overall SWR readings. What I don't understand is why my radio shows basically no SWR (a flat 1.0) across the entire band as long as the antenna is hooked directly to it. it's almost like the radio's built in SWR meter doesn't work at all? I know the antenna isn't tuned "PERFECT" across the entire band.

[Deleted User 14541]

Adding the jumper should not change anything but swr readings can be different at different points on the coax. If the reading changes remember nothing at the antenna end has really changed.

Reread my last post and let Google be your friend. I gave you a couple of reasons you may be seeing what you're seeing. Coax length does not change the swr at the feed point of the antenna but can change the reading at the meter.

You may or may not be new to this but there are some things you need to wrap your head around. It takes time so read and experiment every chance you get. Make sure your bull poo filter is turned on when you read anything about radio on the Internet.

You'll find all kinds of formulas for coax lengths and a few recommended lengths that some people have had good luck with. Don't cloud your mind with this. It has its place but it's not time yet.

[MDYoungblood]

What radio brand and how old is it?

3's

Greg

[High_Speed]

What radio brand and how old is it?

3's

Greg

Uniden Bearcat 980ssb
New out of the box last week. The antenna is a Wilson 500 mag mount, also new last week.

[1206FL]

Your external meter is reading correctly IMO, as I know those antennas as very narrow banded. You could cut some whip off I would think at 1.5 on 40 vs. 1.05 on 1. But the internal meter I have found even with the mic gain down you sometimes have issues trying to get the calibration right. Trust the external meter and maybe see if you can adjust the internal meter via the pot that controls the swr calibration. This is just my experience with mine. Hope this may help.

[MDYoungblood]

The Wilson 500 has a 57" whip, same as the K40, it's also shunted load would helps in the SWR department. If you have the SWR set at 1:1 on channel 19 that antenna should read higher at 1 and 40, about 1.3 to 1.5 .
To see how accurate it is move the antenna to a different location, trunk or hood, and see if it reads different from the external. Did you try the barrel connector and the jumper, adding that extra length of coax does change how the antenna reacts.

3's

Greg

[ogdoa]

I never trust the built in radio swr meter but I do use it as a reference. If that meter is spiking I hook up another swr meter and work from there. With those readings I would not be worried. There is a reason that external meters have a red mark above 3.0. I am usually good with 1.5 and below. Running the jumper and external meter could raise your swr and that may be why you have the 2 different readings. You may be lucky and running a flat 1.0 without them in line but I doubt it. If you are really concerned about your swr being a little lower hook up an analyzer and it will tell you what your swr is.

[High_Speed]

The Wilson 500 has a 57" whip, same as the K40, it's also shunted load would helps in the SWR department. If you have the SWR set at 1:1 on channel 19 that antenna should read higher at 1 and 40, about 1.3 to 1.5 .
To see how accurate it is move the antenna to a different location, trunk or hood, and see if it reads different from the external. Did you try the barrel connector and the jumper, adding that extra length of coax does change how the antenna reacts.

3's

Greg

I have not had the chance to hook up a barrel connector. I'll look for one of those today and try that to see if anything changes.

-- Friday, 05 June 2015, 8:21 AM --

Adding the jumper should not change anything but swr readings can be different at different points on the coax. If the reading changes remember nothing at the antenna end has really changed.

Reread my last post and let Google be your friend. I gave you a couple of reasons you may be seeing what you're seeing. Coax length does not change the swr at the feed point of the antenna but can change the reading at the meter.

You may or may not be new to this but there are some things you need to wrap your head around. It takes time so read and experiment every chance you get. Make sure your bull poo filter is turned on when you read anything about radio on the Internet.

You'll find all kinds of formulas for coax lengths and a few recommended lengths that some people have had good luck with. Don't cloud your mind with this. It has its place but it's not time yet.

Thanks for the info. Clearly I have some educating to do for myself. Which, that's really all I'm trying to do here is learn. I'd like to eventually get my ham ticket. But yes, I'm struggling to understand right now. So if I'm understanding you correctly, you're saying that the radios meter may be accurately reading 1.0 now across the band, but when I introduce the meter and jumper into the mix, this is causing the readings to jump up a bit? The other night I hooked up the external meter and used it while I cut down the whip some until I got the readings to where they are currently.

-- Friday, 05 June 2015, 8:22 AM --

Edit: But after cutting the whip and getting my SWR to read (through the external meter and the radio meter while the external was hooked up) around 1.05 on ch1 and 1.45 on ch40. But then, after I unhooked the external and plugged the antenna directly into the back of the radio again, the radios meter just reads 1.0 across the entire band. That's what's really confusing me.

[Deleted User 14541]

So if I'm understanding you correctly, you're saying that the radios meter may be accurately reading 1.0 now across the band, but when I introduce the meter and jumper into the mix, this is causing the readings to jump up a bit?

Yes it is possible.

But after cutting the whip and getting my SWR to read (through the external meter and the radio meter while the external was hooked up) around 1.05 on ch1 and 1.45 on ch40. But then, after I unhooked the external and plugged the antenna directly into the back of the radio again, the radios meter just reads 1.0 across the entire band. That's what's really confusing me.

It is possible something is wrong with the internal meter but it seems to be working good enough. With the numbers you have you are splitting hairs for no gain. An SWR meter reads reflected power and gives you a reading. Without an antenna analyzer you can't measure impedance and reactance, this is what you want to see when splitting hairs. Tuning out the reactance will make the antenna perform the best but that point might not be the lowest SWR. So keep in mind that tuning for a flat SWR may not always be best, that's why I would call it a day and talk on it.

[southwind]

What good topic and really great suggestions. Bottom line, the numbers your talking about will not make any difference on the other end, that's what I care about, how do I sound. BTW, take another radio, set it up with same meter hook up, and compare. Your new radio meter could be off, will not make any difference when you make contact. JMHO, good evening from Georgia Dawg country.