MikeOK

I just lfinished my install of a Cobra 75, and on the SWR meter I got 1.2 on ch 1, 1.4 on ch 20, and 2.2 on ch 40.
It's the best I could get using a 4' tunable firestick. I have the tuner turned down all the way (shortest). I heard lots of staticky transmissions but I'm way out in the boonies so I didn't expect much. Are these SWR readings acceptable?

kbp810

Those readings are fine; or at least good enough that you shouldn't toast your radio when transmitting on/near 40. You could also try removing the tuning tip and see what you get, if you wanted to keep messing with it.

Also just to clarify, your SWR impacts transmitting; won't have any bearing on receiving.

MikeOK

Thanks. I did try it with the screw completely out and I was over 3 on channel 1. I went back out and tinkered with it a little more and I ended up with 1.6 on both 1 and 40, so I think I can live with that.
wow, it took me over 5 hours to install the ultramount and cb. The ultramount instructions said you should be able to do it in 30 minutes. No way!

Jdover

Actually SWR is a two way street. The more resonant your antenna is not only the better your outgoing transmitting power is the better your receiver can detect incoming signals. It Benicia your radio both ways.

Jdover

Sorry about the misspelling, "benefits"

coolhand129

Try to tune for the lowest reading at the middle is the band. Like channel 20. That should make the rest of them close to resonant.

OnBelay

^^ This. Resonance isn't a function of SWR, but resonance and SWR are fairly well correlated with most off the shelf antennas.

Anyway, the Firestik antenna is highly sensitive to the plastic cap being in place. Your SWR can vary widely when you remove it; I've seen my SWR go from 1.0 to 3.6! Yes the cap is invisible from an RF standpoint, but it affects capacitance and hence SWR.

As others stated, your SWR is fine. The antenna is long, so it is probably reacting (again capacitance) with nearby metals. All you can do is bond your antenna mount well and get as much of the top of the antenna above your roof line. Remember, the FS is top-loaded and ground plane dependent.

Jdover

You are exactly correct in your observation.