Okay, I have a problem with my new tractor. It is a new International model 8600 daycab conventional. I tried a Wilson 5' Silverload on the back of the cab (got a 1.7 SWR), also tried a 10K single coil, 12" mast (set off the SWR warning light on my Magnum S6). I decided to try going to the mirror arms with co-phased Wilson 5'. At the CB shop I go to, the tech used an MFJ antenna analyzer and told me that I had a 2.1 flat match. But he said he'd never seen something like this before. He told me that I had that same 2.1 from about a "band and a half below CB channels to about two bands above CB channels." The mirrors are black powder coated, but I took the brackets off and filed the coating off to get a bare metal contact, changed the studs and coax to better quality than what the tractor came with. What else can I do? I did notice that the new Cb shop coax, co-phase harness was RG8X instead of RG59. But with the factory installed coax, I was getting the same readings. Any ideas?
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Antenna Question/Problem
- Thread starter spiderman5095
- Start date
your mirror brackets may not be grounded to the frame of the tractor. if you have a multimeter see if you have continuity from the mirror bracket to the frame and places in between like frame to tractor body ect.
edited: cause master chef was right. just get rid of the co-phase.
edited: cause master chef was right. just get rid of the co-phase.
I'm a little confused by your post. So lets start here.....
Use a single antenna. Use RG58 or RG8X (50 ohm) coax. Make sure everything is grounded properly.
I never recommend dual antennas to anyone! If you choose to run dual antennas, the phasing harness needs to be made of RG59 (75 ohm) coax. This will hook DIRECTLY to your radio! FL's comments above are in error or I read them wrong.
2:1 SWR is not a "flat match". Not sure what 2.1 is so I'm assuming you mean 2:1. You should have at least a 1.5:1 (everything is something to 1..... x:1)
Use a single antenna. Use RG58 or RG8X (50 ohm) coax. Make sure everything is grounded properly.
I never recommend dual antennas to anyone! If you choose to run dual antennas, the phasing harness needs to be made of RG59 (75 ohm) coax. This will hook DIRECTLY to your radio! FL's comments above are in error or I read them wrong.
2:1 SWR is not a "flat match". Not sure what 2.1 is so I'm assuming you mean 2:1. You should have at least a 1.5:1 (everything is something to 1..... x:1)
what happened to the optional matching links (wire and terminal) at the base stud of the wilson silver loads?
Okay, sorry I didn't explain correctly. The CB guy said that I had a 2.1:1 across about 4 and a half bands of channels. Without hardly rising at all. I just tried connecting a single antenna with a new 18' RG8X on each mirror arm (one at a time) and I got a 1.3:1 on channel 1 and a 1.4:1 on channel 40. When I hook up the co-phase harness, it jumps to a 1.9:1. On my other tractor on the back of the cab, I was getting a 1.2:1 pretty much across all 40.
Try RG59 75 ohm phasing harness. OR go with the single antenna on one mirror! If you are pulling flatbeds, ONE antenna in the center-rear of the cab will do fine!
CWM
CWM
I'm pulling 53' van trailers. The Wilson 5' I had on the back was tall enough to "hear" over top of the trailers and did a great job. I'm still trying to figure out the "plan of attack" for this type of tractor. Unfortunately, it will probably have to wait for spring and warmer weather. Also, the Cb tech said that my meter was accurate on Cb channel 1 (compared to his MFJ antenna analyzer). When I tuned each antenna by itself with an 18' RG8X, I was getting a 1.2:1. Another question: I just bought a co-phase 12' coax harness from a Flying J truckstop. . .(pause for everyone to groan about "truckstop coax"). . .It is essentially the same as the Wilson brand sold right next to it. Same shield rating (97%), same resistance (75 ohm). I haven't had a chance to fiddle with it yet. In four days, I maxed my hours on duty , courtesy of using a vacation day for tomorrow (Friday). So, it will have to wait for Monday, weather permitting.
Truck stop coax
Sorry but I have had nothing but bad experiences from using truck stop pre packaged coax. I buy only made to order now. Oh ya it will work. Sometime compare some good coax with the truck stop junk in regards to RX and TX numbers and your see what I am talking about. The Owner of the Diesel Dummies brand coax gotta be laughing all the way to the bank. LOL
Sorry but I have had nothing but bad experiences from using truck stop pre packaged coax. I buy only made to order now. Oh ya it will work. Sometime compare some good coax with the truck stop junk in regards to RX and TX numbers and your see what I am talking about. The Owner of the Diesel Dummies brand coax gotta be laughing all the way to the bank. LOL
Okay, I took the truckstop coax back and got my money back. I checked my swr reading on the dual antenna setup (factory coax), and it had jumped from 2.1:1 to over 3. I disconnected the driver side antenna from the factory coax and ran the single 18' RG8X to it. When I took an swr reading, it showed over 2:1! What is going on? I took the Wilson 5' fiberglass off the driver side mirror mount and put my Monkey Made MM9 on and tuned it as low as I could get it which turned out to be a 1.5:1. The problem is that the guys I run with can hear quite a bit further with their antennas on the back of the cab (all daycabs). I guess I need to figure out where to drill under the rubber floormat to run the coax into the cab from the back. Question: What type of antenna would do better on the back; 5' fiberglass, 10k with a long mast, or what? I may still go with the mirror mounts and run good coax to them, but that would mean running the coax in through the wing windows. When you do that, you have a loop of coax hanging in your upper left hand view and that is irritating. Thanks for the replies, though.
you indicated in your posts that one of the antennas you used was the Wilson FGT Silver Load in the 5' model. with a dual harness constructed of two 18' lengths of quality 75 ohm cable those antennas could have been matched exceptionally well by using the impedance matching transformer links attached to the base stud of the silver load antennas. if you never saw those wire links on the antennas you should ask why they were cut and removed. the connection of one or both of these links along with re-tuning of the individual antenna/s is required for proper matching on these particular trucks. most idiots at cb shops cut them without reading the instructions. btw, the antenna caps affect tuning and need to be in place at the top of the antennas as well. the presence (or absence) of the caps can account for 10's of khz. to 100 khz +/- excursions from the target resonant frequency.
http://www.wilsonantenna.com/fg.htm
if you'll look closely at the picture you'll see the matching link running across the bracket and connected to one of the hardware sets at the antenna mount. see also the second line in the "advantages" list, "Exclusive impedance matching transformer lead".
furthermore, if maximum signal to the front and rear of the rig is what you're looking for then dual antennas are the way to go. the directional effects are still present down to one-eighth wave spacing as long as the top two thirds of both antennas are in unobstructed view of each other. also, dual antennas tend to be twice as broad as a single antenna, an important advantage if you're using an export radio. the elimination of the links and the wrong feedline type and lengths has turned an otherwise 30 minute or less job into a self-perpetuating clusterfuck.
if the people in these cb shops are telling you that one antenna works better than two then you had better believe them because what they're really telling you is that they don't know how to properly install and tune dual antennas in the first place.
http://www.wilsonantenna.com/fg.htm
if you'll look closely at the picture you'll see the matching link running across the bracket and connected to one of the hardware sets at the antenna mount. see also the second line in the "advantages" list, "Exclusive impedance matching transformer lead".
furthermore, if maximum signal to the front and rear of the rig is what you're looking for then dual antennas are the way to go. the directional effects are still present down to one-eighth wave spacing as long as the top two thirds of both antennas are in unobstructed view of each other. also, dual antennas tend to be twice as broad as a single antenna, an important advantage if you're using an export radio. the elimination of the links and the wrong feedline type and lengths has turned an otherwise 30 minute or less job into a self-perpetuating clusterfuck.
if the people in these cb shops are telling you that one antenna works better than two then you had better believe them because what they're really telling you is that they don't know how to properly install and tune dual antennas in the first place.
Tuning dual antennas
I haven't ran dual antennas for maybe 15 years. But as I remember I would tune both antennas at the same time with the 75 Ohmn coax installed. You have to move both stingers the same distance either direction whichever is called for. Really a pain running back and forth and holding the antennas side by side to get same length. Anyway that's how I did it, seemed to work out.
I haven't ran dual antennas for maybe 15 years. But as I remember I would tune both antennas at the same time with the 75 Ohmn coax installed. You have to move both stingers the same distance either direction whichever is called for. Really a pain running back and forth and holding the antennas side by side to get same length. Anyway that's how I did it, seemed to work out.
Spidey,
I too run duals.......the reason being ,that big 'ole "dump bucket" behind me makes for one heck of a "blocker" for "wave length " :roll: :roll: .....When tuning my Wilsons ( the silver loads or the 2000's) or even my "New Mack" ( firestix in disguise) antennas.... I find it easier to tune the antenna farthest away 1st ( passenger side
) then go the drivers side.......Even with the "New Mack Kit" (heavier coax and connections,the factory boys listened )..my SWRs are 1.2 throught out AM band (only place I'm legally allowed ) .......Only problem with these "NEW" trucks is those HUGE mirror arms....Antenna bracket hardware just went up...Luckily the "Boss' paid for this 1st time around ...
Only other option I would mention (our new Peterbilts did this with great results) is hard mount the Single antenna through the cab roof...Both went with Wilson 5000's with that new "short stinger"....And they never miss a "beat" 8)
Snoope back hiding in the snow....Ho-Ho-Ho
I too run duals.......the reason being ,that big 'ole "dump bucket" behind me makes for one heck of a "blocker" for "wave length " :roll: :roll: .....When tuning my Wilsons ( the silver loads or the 2000's) or even my "New Mack" ( firestix in disguise) antennas.... I find it easier to tune the antenna farthest away 1st ( passenger side
) then go the drivers side.......Even with the "New Mack Kit" (heavier coax and connections,the factory boys listened )..my SWRs are 1.2 throught out AM band (only place I'm legally allowed ) .......Only problem with these "NEW" trucks is those HUGE mirror arms....Antenna bracket hardware just went up...Luckily the "Boss' paid for this 1st time around ...Only other option I would mention (our new Peterbilts did this with great results) is hard mount the Single antenna through the cab roof...Both went with Wilson 5000's with that new "short stinger"....And they never miss a "beat"
8) Snoope back hiding in the snow....Ho-Ho-Ho
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