A bit of a tip for when you're SWR'ing, short aeriels will only work if they're in the roof of a vehicle, anything else and you'll have problems SWR'ing them.
If it's a new aeriel, tape a short piece of wire to the tip of it, therefore extending it, then cut 1/4" off at a time until the SWR readings start to drop below 3. Once you're getting below 3, only trim 1/8" at a time.
hopefully you'll find that the extended piece of wire isn't needed, and that you might actually need to trim the aeriel itself.
Before doing so, make sure all the adjustment on it (if there is any) is fully closed up.
Now by checking on CH1 and CH40, you should get different readings, if the worst reading is on CH40, then it's still too long, if the worst reading is on CH1, then it's now too short.
A reading below 2:1 is acceptable, but anything below 1.5:1 is good.
If it's a new aeriel, tape a short piece of wire to the tip of it, therefore extending it, then cut 1/4" off at a time until the SWR readings start to drop below 3. Once you're getting below 3, only trim 1/8" at a time.
hopefully you'll find that the extended piece of wire isn't needed, and that you might actually need to trim the aeriel itself.
Before doing so, make sure all the adjustment on it (if there is any) is fully closed up.
Now by checking on CH1 and CH40, you should get different readings, if the worst reading is on CH40, then it's still too long, if the worst reading is on CH1, then it's now too short.
A reading below 2:1 is acceptable, but anything below 1.5:1 is good.