So I've set up the CB on both my cars and on the Corolla I'm at about 1.5 SWR on either ends of the spectrum. The power line goes directly to the car's battery, the antenna is a K40. Anything that I can do to improve the SWR?
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Making the CB radio perform
- Thread starter Love Machine
- Start date
cockpitbob
NES Member
1.5 is fine. Even at 2:1 you are only losing about 10%. Since 1 S-unit is 4to1, that 10% loss is nothing. Where do you have the antennas mounted? If they are on the trunk, adding a couple grounding straps to ensure the lid is well grounded to the body may help.
JDL
NES Member
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Tuning at its best is only 1.5.
Another question then - what's the best way to mount the grounding straps? The bolt holding the trunk lid work perfectly on one end, but I don't know where to mount them on the car's body.
Another question then - what's the best way to mount the grounding straps? The bolt holding the trunk lid work perfectly on one end, but I don't know where to mount them on the car's body.
I used to tin the braid a bit with solder, drill holes in it in a couple places, then strategically grind off a little on some kind of metal part in the car, and use self tapping screws to secure it in place. I think I was able to use some piece of metal on the rear deck where the speakers are. Small bolts with lock washers would probably work better. (although in my 89 tempo I had at the time, the straps never came loose... that car had massive RFI problems so I went full retard with ground straps trying to bond the piss out of eveyrthing. )
Also, if you ever upgrade your juice.... ditch the K40. It says 500W rating but that's a lie, I smoked mine with less than 200W. Great antenna though if you're not running an amp. There's a stupid ****ing capacitor in there that smokes given half a chance.
-Mike
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2:1 is awful IMHO. It might only be 10% but its going to beat the shit out of his finals (CB radios don't clamp output usually) He should be able to get it 1.1:1 on at least whatever the center is. 1.5 is fine to get by on, though.
-Mike
cockpitbob
NES Member
Doc, agreed. IMHO keeping the finals safe is only real reason to strive for a really low SWR.
Regarding bonding, I usually have to drill a hole or 2. I've been using 12AWG with with crimp ring lugs. They say braid is better, but I've never seen data to convince me it's enough to matter. Just keep it short.
Regarding bonding, I usually have to drill a hole or 2. I've been using 12AWG with with crimp ring lugs. They say braid is better, but I've never seen data to convince me it's enough to matter. Just keep it short.
I'm only using the 4W transmitter, no amps for me. I'm going to look around for more bolts to hang the braid on to.
