Im doing an install on a semi truck, I've got a cophase setup of 2 Wilson 2000 antennas and just purchased the Firestik FireRing (75ohm RG59) Cophase harness to go with it. After purchasing I see alot of recommendations for LMR240 but they all seem to be single antenna setups. Which is better for my setup, and is it going to make a big enough difference that I shoukd ditch the RG59 for the LMR240?
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Cophased Antennas LMR240 vs. RG59
- Thread starter Antler24
- Start date
I guess thats as "cut and dry" as it gets, thanks guys, I knew I must have been missing something.
Two 50-ohm antennas in parallel are like two 8-ohm speaker cabinets in parallel.
The speaker impedance of the two parallel 8-ohm cabinets is now half the rating of each single cabinet, 4 ohms.
Same deal with two 50-ohm antennas.
Odd as it sounds, using the correct length of 75-ohm coax makes each antenna into a 100-ohm load. Put them in parallel and now you're back to the 50-ohm impedance the radio needs.
50-ohm coax won't do this impedance step-up properly like the 75-ohm cable will.
73
The speaker impedance of the two parallel 8-ohm cabinets is now half the rating of each single cabinet, 4 ohms.
Same deal with two 50-ohm antennas.
Odd as it sounds, using the correct length of 75-ohm coax makes each antenna into a 100-ohm load. Put them in parallel and now you're back to the 50-ohm impedance the radio needs.
50-ohm coax won't do this impedance step-up properly like the 75-ohm cable will.
73
I had no idea. Everything I had seen was 50 ohms in LMR-240. Haven't looked enough at LMR to see that. All the hoop la about LMR has driven the price up. Not too impressed with it either.
Unless you plan on running a bazzillion watts RG-59 will be fine
Where can I find one of those Bazzillion Watt Lieeeennyuure's, Oldtymer? I know they used to build them tube types that would black out the power grid back in the day. I just gotta have one. One that will make the neighbors cat spaz out and run into walls when key down.
Where can I find one of those Bazzillion Watt Lieeeennyuure's, Oldtymer? I know they used to build them tube types that would black out the power grid back in the day. I just gotta have one. One that will make the neighbors cat spaz out and run into walls when key down.
Long day. Man, I needed that laff.
Where can I find one of those Bazzillion Watt Lieeeennyuure's, Oldtymer? I know they used to build them tube types that would black out the power grid back in the day. I just gotta have one. One that will make the neighbors cat spaz out and run into walls when key down.
I had one back in the 70's, used to come in on the PA system in a church 2 miles away.
I decided not to run it Sunday mornings, keep the peace.
Since you were already Present in the Spirit, is it true as rumor has it that the local grocery store, barber shop, post office, etc became the happy hunting ground for conversion attempts and testimonials such that you had to drive to neighboring towns ever after?
Why, even today, little children point to you, and . . . .
.