My company runs Sterling trucks and several drivers have been having major problems with them. First,the SWR isn't the same from one day to the next. I've gone from a 3:1 match one day...and the next day had a 1.2:1 match. When it rains our match tends to be worse than on dry days. We have run ground wires from the mount to just inside the cab with a cleaned to metal area with minimal help and on some days it will actually make the SWR worse. We have tried direct ground wiring to negative battery post, grounding to the same ground as the radio and other generic metal screws or bolts.
For some reason, some of us can receive a reasonable distance of 3-4 miles while others can only receive 7 tenths of a mile. Mine for instance will only hear someone a mile away, but if someone else is talking within 3 miles or so...I will get complete static over their entire transmission. My radio is apparently picking them up fine, but a blanket of static is covering their transmission. At the same time, my radio will talk to anyone within 3-5 miles no problem. Another driver's radio is only getting out about 7 tenths of a mile up to about 1 mile before it mysteriously fades out.
I'm thinking we need to ground the heck out of everything. Some background info...
my truck has a Detroit, all others are Mercedes Benz motors.
all trucks are automatics...extra electrical componets to shift the gears.
We all run different Cobras, mine new 29ltd Classic, others have 200gtl and an older 25...all peaked and tuned.
all radios are wired to a main positive hub (about six feet of wire in dash)that has been checked with a meter to be putting out the same amount of power (and using same amount went transmitting)as the positive terminal on the batteries. all static is coming in through antenna, not power leads.
me and the 200gtl owner are running 50 ohm 97% sheilded Belden coax...brand new coax to one Wilson. His a 2000...mine a 5000.
My radio just came out of a different truck I drove and I had no problems with SWR (1.1 or 1.2:1) or being able to talk and receive perfectly....Same with the 200gtl's setup.
The guy with the 25 has an s-unit or so of noise with it turned off then it sky rockets to about 7-9 s-units when the key is turned to the on position. The 200gtl's only adds about 1-2 s-units of noise. Mine adds virtually none, even when running. I realize this is the fuel pump, but keep in mind that these are company trucks...not ours.
We have not tried moving the radios or re-routing the coax, but with smaller daycab trucks (no sleepers), we are limited in what we can do. The ceiling in these trucks is cardboard so we can't really relocate radios to mount into ceiling.
I'm gonna try to go in and work on my truck tommorrow and add a second Wilson 5000 to the other side. I've picked up the co-phase 75 ohm identical coax and I'm hoping to improve things at least by going directional. Also thinking of getting those radials to help as they have helped me in the past.
One idea one of the guys came up with was to turn the key to the on position and systematically remove one fuse at a time to see what componets were causing static. i thought this was a brilliant idea except he never did it as everyone is pretty fed up with these problems and we are sick of trying new things. It also doesn't help that this was 5:30 am on a saturday morning and we we're just back from driving all night long and done for the week!
Am I correct in thinking we have to ground everything better meaning cab to chassis, motor to chassis, door to cab, on and on.....or do you think it's something else?
For some reason, some of us can receive a reasonable distance of 3-4 miles while others can only receive 7 tenths of a mile. Mine for instance will only hear someone a mile away, but if someone else is talking within 3 miles or so...I will get complete static over their entire transmission. My radio is apparently picking them up fine, but a blanket of static is covering their transmission. At the same time, my radio will talk to anyone within 3-5 miles no problem. Another driver's radio is only getting out about 7 tenths of a mile up to about 1 mile before it mysteriously fades out.
I'm thinking we need to ground the heck out of everything. Some background info...
my truck has a Detroit, all others are Mercedes Benz motors.
all trucks are automatics...extra electrical componets to shift the gears.
We all run different Cobras, mine new 29ltd Classic, others have 200gtl and an older 25...all peaked and tuned.
all radios are wired to a main positive hub (about six feet of wire in dash)that has been checked with a meter to be putting out the same amount of power (and using same amount went transmitting)as the positive terminal on the batteries. all static is coming in through antenna, not power leads.
me and the 200gtl owner are running 50 ohm 97% sheilded Belden coax...brand new coax to one Wilson. His a 2000...mine a 5000.
My radio just came out of a different truck I drove and I had no problems with SWR (1.1 or 1.2:1) or being able to talk and receive perfectly....Same with the 200gtl's setup.
The guy with the 25 has an s-unit or so of noise with it turned off then it sky rockets to about 7-9 s-units when the key is turned to the on position. The 200gtl's only adds about 1-2 s-units of noise. Mine adds virtually none, even when running. I realize this is the fuel pump, but keep in mind that these are company trucks...not ours.
We have not tried moving the radios or re-routing the coax, but with smaller daycab trucks (no sleepers), we are limited in what we can do. The ceiling in these trucks is cardboard so we can't really relocate radios to mount into ceiling.
I'm gonna try to go in and work on my truck tommorrow and add a second Wilson 5000 to the other side. I've picked up the co-phase 75 ohm identical coax and I'm hoping to improve things at least by going directional. Also thinking of getting those radials to help as they have helped me in the past.
One idea one of the guys came up with was to turn the key to the on position and systematically remove one fuse at a time to see what componets were causing static. i thought this was a brilliant idea except he never did it as everyone is pretty fed up with these problems and we are sick of trying new things. It also doesn't help that this was 5:30 am on a saturday morning and we we're just back from driving all night long and done for the week!
Am I correct in thinking we have to ground everything better meaning cab to chassis, motor to chassis, door to cab, on and on.....or do you think it's something else?
