Gambi80 Posted September 4, 2009 Share Posted September 4, 2009 I've got a question about the 'static' in my cb radio. When the key is turned to 'on' and/or the engine is running, there's a ton of static coming through the CB to where I have to have the squelch cranked up pretty good. BUT, when the key is on the 'acc' position (turned back) there is hardly any static. Why is this? I've tried hooking the radio straight to the battery, both positive and ground and started the truck...the static prevails. Is the cab ground bad? Should I ground the radio straight to the frame? Quote Ever wonder how a blind person knows when to stop wiping? Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/ Share on other sites More sharing options...
Barry Posted September 4, 2009 Share Posted September 4, 2009 I've got a question about the 'static' in my cb radio. When the key is turned to 'on' and/or the engine is running, there's a ton of static coming through the CB to where I have to have the squelch cranked up pretty good. BUT, when the key is on the 'acc' position (turned back) there is hardly any static. Why is this? I've tried hooking the radio straight to the battery, both positive and ground and started the truck...the static prevails. Is the cab ground bad? Should I ground the radio straight to the frame?Check the antenna ground. Sometimes the ground at the mirror bracket is no so good. Just try a jumper from the frame to the mirror bracket and see if it improves. Quote Barry - Watt's Truck Center Parts Manager and BMT Webmaster...1-888-304-MACK Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39926 Share on other sites More sharing options...
other dog Posted September 4, 2009 Share Posted September 4, 2009 I drove a T800 that did the same thing-the more things you turned on,like lights,heater,AC,etc. the worse it got.It was the first truck I drove with electronic/computer control. If the antanae ground doesn't work you can buy a noise reducer thing that goes between the coax and the radio at any CB shop.I don't know what you call it so I call it a "noice reducer thing". Quote Producer of poorly photo-chopped pictures since 1999. Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39936 Share on other sites More sharing options...
ThaddeusW Posted September 4, 2009 Share Posted September 4, 2009 I drove a T800 that did the same thing-the more things you turned on,like lights,heater,AC,etc. the worse it got.It was the first truck I drove with electronic/computer control. If the antanae ground doesn't work you can buy a noise reducer thing that goes between the coax and the radio at any CB shop.I don't know what you call it so I call it a "noice reducer thing".You are probably talking about a band pass filter. It lets the 27MHz CB frequency through but blocks frequencies above and below 27MHz. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39944 Share on other sites More sharing options...
Gambi80 Posted September 4, 2009 Author Share Posted September 4, 2009 Check the antenna ground. Sometimes the ground at the mirror bracket is no so good. Just try a jumper from the frame to the mirror bracket and see if it improves.If the mirror bracket isn't grounded, how do I ground the antennas? Would a magnetic mount to the top of the cab work better? What's odd is that when I have the key on 'accessory' there's almost no static, but as soon as I turn it to on there's a ton of static. Quote Ever wonder how a blind person knows when to stop wiping? Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39945 Share on other sites More sharing options...
other dog Posted September 4, 2009 Share Posted September 4, 2009 If the mirror bracket isn't grounded, how do I ground the antennas? Would a magnetic mount to the top of the cab work better? What's odd is that when I have the key on 'accessory' there's almost no static, but as soon as I turn it to on there's a ton of static.If you have a steel cab grounding shouldn't be a problem. I had a fiberglass cab and just ran a fairly heavy gauge wire from the antenna mounting bracket to a good ground under the hood somewhere. It didn't help my situation any. Quote Producer of poorly photo-chopped pictures since 1999. Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39946 Share on other sites More sharing options...
Bollweevil Posted September 5, 2009 Share Posted September 5, 2009 I've got a question about the 'static' in my cb radio. When the key is turned to 'on' and/or the engine is running, there's a ton of static coming through the CB to where I have to have the squelch cranked up pretty good. BUT, when the key is on the 'acc' position (turned back) there is hardly any static. Why is this? I've tried hooking the radio straight to the battery, both positive and ground and started the truck...the static prevails. Is the cab ground bad? Should I ground the radio straight to the frame? Chasing a performance problem with a CB radio, can be frustrating to say the least. Has the Radio ever worked to your satisfaction? Have there been any changes to the radio configuration, antennas, co-ax. To be sure that we are on the same page, when you say static, are you refering to the background noise that you would normally associate with a CB? Can you go to an unused channel back the squelch all the way off turn the volume down, and with all accessories off, turn the switch on and hear an increase in volume? When you start the truck can you hear the alternator in the background noise, or the AC fans. These kind of problems can be related to a bad ground, a bad alternator diode, which you can eliminate by temporally disconnecting the hot wire from the alternator. or a bad coaxial cable. Check your cab ground. Grounding both radio and antenna to the frame is not a bad idea. What are you using for cable. A co-phased set up will not perform as well with RG58, as RG59. Quote Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39953 Share on other sites More sharing options...
Gambi80 Posted September 5, 2009 Author Share Posted September 5, 2009 Chasing a performance problem with a CB radio, can be frustrating to say the least. Has the Radio ever worked to your satisfaction? Have there been any changes to the radio configuration, antennas, co-ax. To be sure that we are on the same page, when you say static, are you refering to the background noise that you would normally associate with a CB? Can you go to an unused channel back the squelch all the way off turn the volume down, and with all accessories off, turn the switch on and hear an increase in volume? When you start the truck can you hear the alternator in the background noise, or the AC fans. These kind of problems can be related to a bad ground, a bad alternator diode, which you can eliminate by temporally disconnecting the hot wire from the alternator. or a bad coaxial cable. Check your cab ground. Grounding both radio and antenna to the frame is not a bad idea. What are you using for cable. A co-phased set up will not perform as well with RG58, as RG59.I've got the co-phase (dual) coax. The noise isn't engine noise, alternator or anything like that. It's just the constant static...similar to when you'd turn your tv to an unused channel and it was just 'snow'. I can have the key on accessory and there's nothing. When I either start the truck or just turn the key to 'run', the static starts. I'm thinking when the main breaker/relay associated with the key being on on, it starts. It's the same with the key on as it is with the engine running. It's hard to explain and I know CB's are a pain in the ass. The coax, radio (tuned/peaked) and antennas are all new. It pisses me off because I know the radio works awesome with the key on accessory. Quote Ever wonder how a blind person knows when to stop wiping? Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39955 Share on other sites More sharing options...
Rob Posted September 5, 2009 Share Posted September 5, 2009 I've got the co-phase (dual) coax. The noise isn't engine noise, alternator or anything like that. It's just the constant static...similar to when you'd turn your tv to an unused channel and it was just 'snow'. I can have the key on accessory and there's nothing. When I either start the truck or just turn the key to 'run', the static starts. I'm thinking when the main breaker/relay associated with the key being on on, it starts. It's the same with the key on as it is with the engine running. It's hard to explain and I know CB's are a pain in the ass. The coax, radio (tuned/peaked) and antennas are all new. It pisses me off because I know the radio works awesome with the key on accessory.Get yourself a 2500 ufd, 50VDC capacitor and tie one lead to your power wire leading to the radio, the other lead to a good chassis ground. What you are hearing with the key in the "on" position is the electronics, (ECM) that let the engine run. The shielding for RF energy is terrible in the automotive world and the spurious noise you are hearing is resonating through the truck's electrical system. Noisy, low buck components contribute to the phenomenon as does the alternator magnetic fields. There is not very much powered up when the keyswitch is in the "accessory" position, mainly the engine ECM, and the alternator charging circuit. This noise is easily "shorted" to ground potential with a capacitor.When you tie one leg of a cap to the electrical signal and the other to ground the spurious noise will pass through the capacitor allowing a "smoother" DC voltage to pass to the radio power supply. By law consumer electronics have to accept any outside interference of RF energy or be licensed such as powerful radio transmitters. A citizens band radio is limited in it's power output and therfore immune to government intervention. An automotive "noise filter" that you would purchase at a stereo store is nothing more than the above mentioned item in a fancy case. If you can't hide the capacitor out of sight, these a good way to go. Don't eat Other Dogs' mushrooms. I hear he is looking for test subjects.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39959 Share on other sites More sharing options...
ThaddeusW Posted September 5, 2009 Share Posted September 5, 2009 RF/Radio stuff can be a pain in the ass at times. Make sure your coax cable connectors (UHF) are nice and tight with good continuity.co-phasing requires special antenna placement to ensure you are getting the proper gain. Here is an excellent co-phasing guide: http://www.signalengineering.com/ultimate/co_phasing.htmlI would first try to get a single RG-58 50 ohm coax cable with properly terminated UHF connectors on each end and hook only one antenna up and check the results. Grounding both the antenna and radio unit can cause ground loops. If you can, isolate any metal of the antenna(s) and again test to see if the noise is still present.Antennas don't need to be grounded, that's the job of the shield inside the coax cable. If you already tried to directly wire the CB to the battery and the thing still gets tons of noise when the engine is running then you have alternator noise. Like Bollweevil said, does the sound change when the engine revs faster? If so then your going to need to filter out the Alternator noise. Some filters work, some dont. A proper filter will use an LC filter circuit to block and short AC noise and a capacitor to smooth out any fluctuations in the voltage. Also antenna placement is a problem too, especially since you have a co-phase setup. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39962 Share on other sites More sharing options...
Barry Posted September 5, 2009 Share Posted September 5, 2009 Maybe the coax is run too close to the truck's computer or other electronic hardware? You can try bypassing the installed cable and hook a test patch cable from cb to antenna to see if anything changes. Everything is just suggestions, because electronic gremlins are hard to chase down! Quote Barry - Watt's Truck Center Parts Manager and BMT Webmaster...1-888-304-MACK Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39963 Share on other sites More sharing options...
Gambi80 Posted September 5, 2009 Author Share Posted September 5, 2009 Maybe the coax is run too close to the truck's computer or other electronic hardware? You can try bypassing the installed cable and hook a test patch cable from cb to antenna to see if anything changes. Everything is just suggestions, because electronic gremlins are hard to chase down!Unfortunately there aren't many options for a CB mount on a 97 CH. I'm pretty sure it's the computer and/or whatever clicks when the key is turned on producing the noise, because it's the same with the engine running as it is when the key is just on the 'on' position..motor off. Quote Ever wonder how a blind person knows when to stop wiping? Link to comment https://www.bigmacktrucks.com/topic/10547-cb-radio-hook-up/#findComment-39981 Share on other sites More sharing options...
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