|01-28-2012 02:48 AM|
Revived from the dead!
Around the time this post died, I had given up troubleshooting and decided I'd just take it to a shop and have them fix my issues or wait until things at work died down and I'd mess with it then. Tonight I decided to start messing with it...work has been slow so I had nothing better to do.
My goal was to check my grounds from my battery and replace them with higher gauge wire.
So I look at my battery and I have 2 wires coming off the negative terminal...I follow the first one. Aside from being a little corroded at the battery, it goes to a very solid ground on the body toward the rear of the engine bay. Easy enough to replace.
I follow the next one which heads down toward the engine block...but what's this...it looks like it's hooked to an aluminum component of the a/c system. Odd....
I grab it to see where it's bolted down on that component and lo and behold...there's a ring terminal on it and it's not attached to ANYTHING! GAH!
So I replaced that ground...bolted it underneath one of the mounting bolts for my alternator and made a short run back to the battery (I saw the bolt it most likely originally was attached to as there was another ground for some electronics wired there...but the bolt had seized to the ring terminal of that other ground wire and I didn't want to rip those thin little wires out). I also went ahead and replaced the ground to the body just to ensure both my ground wires were nice and fresh. One of these days I'll probably buy enough wire and terminals and replace EVERYTHING on there but that was enough for the time being. It was nearing 2am and I was ready to come home so I decided to call that a night.
I haven't tried to tune my antenna yet, but my engine whine has been significantly reduced with the squelch all the way down...AND I'm actually hearing truckers talking on the interstate. Better yet, I was hearing them clear up near my house and I'm a good 5-10 miles from the interstate. I didn't risk transmitting until I get the antenna tuned, but things are looking good so far...
|09-05-2011 02:57 AM|
More important is where is your antenna mounted? Tire carrier? or body of the jeep?
Wire the radio straight to the battery and take the ground and power wires and twist them together. It also wouldn't be a bad idea to get some ferrite beads has them. This will cut down EMI and the whine people here.
|09-03-2011 01:24 AM|
You've got a couple grounds to think about in this case. Your power ground is the body and frame of the Jeep which is common with the negative battery post. The other ground type is RF ground which is part of your antenna system. One is not necessarily the other. When checking power ground, you're only interested in the DC resistance. For the RF ground, you're looking at impedance as well. Long runs of wire also start looking like an antenna rather than a ground at RF.
What do the condition of your engine and body grounds look like? I know mine were a bit questionable so they got rather significantly upgraded.
|09-02-2011 04:02 PM|
|jeeperharmon||I've been reading this forum and so I went a took a wire brush and cleaned up my taillight mount.. and changed my adapter for the mount and antenna.. I have a cheapo fiberglass antenna.. and a midland 1001z cb with it wired both the ground and the power to the battery.. I do get whining every so often. Which I would like to work on. But I did an swr test and I'm getting a 1:1.2-1.3 reading.. which I am very happy with let's see if it stays that way.|
|09-02-2011 06:52 AM|
No break in the coax...tried the new coax, problems still exist. I'm about to just take the damn radio out into the woods and test the new Glock out on it. I'll record it when I do...
On a more serious note, newest idea...I'm going to try changing my radio ground. First tried to ground to the same grounding strap my headunit is grounded to. Bad idea...when I transmitted to test the SWR, it actually took over my radio speakers. I could even hear myself talk through them...obviously not good on my headunit I'm sure.
I then tried a direct ground to the battery, but thinking about it now...running that small gauge wire through the firewall on the drivers side and along the firewall to the battery (a good 4-5 ft run), could be playing hell on things. I'm going to find me a good grounding point as close to the radio as possible and see what that does. Although I'm not sure if that would cause the high SWR readings or just be the reason why I have a lot of engine noise in the static?
|09-02-2011 01:37 AM|
|bdheaton||You'll get it figured out. Keep eliminating possible problems and you'll vanquish the gremlins.|
|09-01-2011 03:09 AM|
|s3nt3nc3d||Ended up selling my spare radio...however, my radio geek buddy rode with me the other day and I showed him the problem. He says classic bad ground situation. No clue where though...he's thinking I have a tiny break in the coax, so I picked up a new coax today while I was out. Still haven't tested it out...but figured I'd let you folks know I haven't given up yet. Just been busy.|
|08-19-2011 02:49 AM|
|08-18-2011 11:48 PM|
|bdheaton||Transmitting with a shorted or open antenna feedline could definitely damage the transceiver. Without another CB or some test equipment, it could be hard to figure out. Any chance you can exchange the CB you've got now?|
|08-18-2011 12:06 AM|
|s3nt3nc3d||Sorry, I kinda shoved it on the backburner after it recently left me stumped again...my buddy never did get his SWR meter to me to double-check it and now my CB is no longer receiving any transmissions again (I haven't been using it aside from trying to fix the issues at hand--and the only transmitting I've done is when trying to tune the antenna with the SWR meter hooked up). Since it quit receiving I tested to see if my antenna was back to being shorted to the mount and everything there is still good. Now I'm back to wondering if my "new" radio has gone bad...creating a new problem that has nothing to do with the old problem (though probably caused by the old problem). I dunno...it has me so stumped...|
|08-17-2011 11:11 PM|
|bdheaton||Anything new or can we check this one off as fixed?|
|08-13-2011 01:32 AM|
Could be a bad SWR meter. Don't suppose you've got some 2-5W 50ohm resistors? (jk). Keep in mind that DC ground and RF ground are two very different things. With an SO239 stud on a tail light mount you should be getting good grounds for both.
When I put my new stick on the Jeep, I should probably break out my MFJ-259B and see what the complex impedance looks like. I've never checked a CB whip to see if any shunt matching is needed. It probably won't be needed on 27MHz, but I'm curious.
Hamfest tomorrow so I'll be shopping for some radio goodies. Since this one is close to me, I'll be taking the big truck and shopping for stuff that would normally be too expensive to ship.
|08-12-2011 06:44 PM|
Hooked up swr meter at the antenna using the jumper wire there...still pegged it although I was next to a building during that test so I may need to retry in the field later?
Coax center conductors are not shorted to their shields/grounds on antenna wire or jumper...antenna is grounded at the mount and is not shorted to ground. Mount is grounded well...I probed from coax shield at the radio (without swr meter hooked up and antenna wire unhooked) to a bolt on the front end of the body and it was showing a good ground. I'm starting to lean toward a bad swr meter...my buddy was sposed to hook me up with his but the bastard never called me back...he's good at that...
|08-12-2011 10:54 AM|
|sparky||You're using a taillight mount. The doors are far enough away so they won't have a major effect, just the slight changes.|
|08-12-2011 03:32 AM|
|s3nt3nc3d||I've been running my Jeep doorless for the past few weeks...I know that will affect SWR, but will it make it do crazy things such as peg the meter or just slight changes?|
|08-12-2011 03:27 AM|
SO-239 on the bottom of the stud...will try moving the meter and see if that changes things. I didn't mess with the tip this time around, but the last time adjusting the tip didn't change the readings at all (I even swapped antennas...switched my 3' Firestik with my old 4' Firestik). I'm back to the 3' Firestik with a 3" spring on it. Pretty sure my line is 18ft long. Tuning is being done in the most wide open area I have available at work...drive out into the middle of a 40+ acre field. No trees, walls, buildings, etc anywhere close.
I am at least making progress...before I could barely receive transmissions...with squelch all the way down, I'd get 95% static with very faint voices even while driving on the interstate. Now I'm getting typical cb static (light static with squelch all the way down--no static when I adjust it), but hearing full conversations and they're pretty clear...I work a mile or two from the interstate so it's definitely doing its job picking up the signals now.
|08-12-2011 01:43 AM|
Does adjusting the tip (don't forget to put the cap back on before checking) make any change to the VSWR?
Are you using a stud mount with an SO-239 on the bottom or does it have wire lugs?
If the stud has an SO-239 on the bottom, can you move the SWR meter to the antenna side and use your jumper there? Are the SWR readings different? 18ft is a common cable length. That is almost exactly 1/2 wavelength for CB frequencies. The impedance at the radio end of an 18ft transmission line should be the same as at the base of the antenna. If you're using some different length of cable, you could be seeing some other impedance.
The shorter the antenna the more tricky they are to tune. Are you tuning the antenna in a garage or near any large metal structures?
|08-11-2011 11:58 PM|
|s3nt3nc3d||Okay, now I'm stumped... I AM receiving transmissions now, however when I went to tune my antenna, SWR readings on both channels 1 and 40 are pegged in the red. I'm going to borrow a buddy's SWR meter when he digs it out and see if I've got a faulty meter. I checked the resistances on the new antenna stud after getting the high SWR readings and everything is still fine there...and radio was still receiving just fine so now I'm just sitting here scratching my head. Ugh.|
|08-11-2011 03:41 PM|
|s3nt3nc3d||Swapped out antenna studs and installed the spring...my main issue appears to be resolved. I am receiving transmissions which is an improvement in itself...still need to tune the antenna but just figured I'd post saying I'm getting somewhere...lol|
|08-10-2011 10:08 AM|
I've got my defroster cover panel laying at work with my SWR meter wired into my cb setup and shoved down in the hole it left behind due to getting sick of disassembling and reassembling everything. Also have a JKS adjustable trackbar sitting at work awaiting installation as soon as I pick up a new replacement bolt for the axle side mount--it started popping hardcore after my lift even though I relocated it per the directions so I said screw it and bought an adjustable.
I had a budget of $3-4k for my lift, radio, and various other mods...I'm approaching $5-6k now due to unforeseen complications and other general maintenance items requiring replacement (ie wheel bearing started to go right after the lift). It never ends...
I checked the UPS tracking info for my parts...should be here today, so if I get a chance, they'll be installed tomorrow unless I get home early enough tonight.
|08-10-2011 01:15 AM|
|bdheaton||Welcome to the JMCC! (Jeep Maintenance Complications Club) Mine is still torn apart while I'm awaiting parts. Every time I took off a layer of the dash, I found more wiring atrocities from the PO. I'm down to 2 parts that are somewhere in UPSland before I can start putting everything back together. Tonight I got majorly POd at the torx bolts holding the windshield brackets. I've got to remove the front facing ones to install my mirror relocation brackets and light brackets. Of course one of them stripped out the torx head. I ended up ordering 100 bolts/nuts/washers in stainless steel to replace them. That was the smallest quantity I could find that would ship immediately. Grrrr...|
|08-10-2011 12:02 AM|
|s3nt3nc3d||Thanks for the info...still waiting on the new stud to arrive (figures nobody locally sells radio stuff so I ordered the one online--it's been shipped, just hasn't gotten here yet). Figures my Jeep has to be complicated...my truck was so easy. Install, plug in, tune, done. Worked great in bout an hour. My Jeep...nightmare. lol|
|08-09-2011 10:16 PM|
Have you seen any changes with the new stud mount? I just pulled one out of my collection to check the arrangement of insulating washers.
The one I pulled out is designed to have wire lugs directly attached to it. The bolt has insulating washers with a shoulder facing up into the top plate hole on both sides. I would expect. The center conductor of the coax is attached between the bolt head, star washer, and insulating stud on the bottom of the mount. The shield connection would simply go to one of the stud mounting bolts.
A 3/8-24 stud with an SO-239 base would only have one insulating washer with shoulder. That washer should go on top of the mount with the shoulder facing down into the top plate hole. In this case, the outer ring of the SO-239 connector is connected to ground by design. The center pin is the one actually connected to the antenna.
As to engine noise, there are lots of ways engine noise can get into your radio. Before troubleshooting that, I would definitely get the antenna mount issues cleaned up and make sure you've got a good solid ground on both the antenna mount and the radio. Does your radio have a grounding stud in addition to the negative power lead? If so, it should connect to a good ground as close to the radio as possible. Right now, you know you've got issues at your antenna mount. Once you get them resolved, the ignition noise may well go away.
The first thing to figure out is whether the interference is getting into the radio via the power leads (conducted interference) or via the antenna (radiated interference). If you disconnect the antenna, terminate the antenna connector on the radio (preferably with a 50ohm terminator - shorted will work too - DON'T TRANSMIT!), and the interference still persists - you've got a conducted interference problem. Your work will center around the power leads and ignition system under the hood. If the interference goes away, you've got a radiated interference issue.
|08-08-2011 06:36 AM|
Still having problems but I think I pegged the cause now...I swapped radios AND antennas over the weekend. Problem still exists.
When running continuity tests, I realized that while my antenna is no longer shorted to the mount, it's also no longer grounded at the mount (that second washer prevent the short but also prevented the stud from properly grounding if I'm understanding how the stud works correctly). I again wrapped the stud in electrical tape just where it goes through the mount (where I believe a Nylon sleeve is missing). I got the stud to ground where it should while not being shorted to the antenna. Everything read perfect on the meter.
Took it out with the SWR meter and transmitted once to set SWR... BLAMMO...instant SWR problems. Checked stud with the meter, antenna was shorted to ground again. My thought is that the electrical tape is not working as a rigged up insulator and as soon as I transmit, it eats through the tape or something.
Regardless...I purchased a new mounting stud last night so we'll see if that solves my problems. Something is telling me I got a defective stud (or rather not sure if it's part of the stud...but the part that screws onto the underside of the stud where the coax screws on). Also picked up a spring for my antenna so raise it up just a little higher and help protect it from being snagged on branches and such.
I also was getting a lot of engine/alternator noise in my radio when I'd turn it on...the static would "rev" with my engine. I figured it was due to my power source (cig lighter) so I hardwired the radio directly to the battery using a relay to key it on/off with the ignition. Made the mistake of grounding it to the same ground as my headunit...which was kind of comical...when I would transmit, it would come out my radio speakers. Whoops...
Decided to ground it directly to the battery as well...but still getting engine noise. Is that due to the antenna not properly grounding at the mount?
|07-28-2011 10:31 AM|
|bdheaton||Glad to hear you're getting close to the fix. Depending on the quality of the radio, damage may have been done to the transmitter by transmitting into a shorted antenna. You'll know once you recheck the SWR and see if you're still getting transmitter output.|
|07-28-2011 01:24 AM|
I think I got it...didn't think to disconnect the radio when checking continuity, which having taken electronic troubleshooting classes, I should have thought to do that first thing.
Unhooked the wire at radio...probed center conductor and barrel connector...no continuity whatsoever. Since I added the nylon washer and changed the antenna height I should prolly hook the SWR meter up and double check my SWR readings and possibly re-tune depending on the readings I get...and then see if it works. If not, problem will have to be in the radio. I'm grounded good...through taillight bolts and a wire from mount to roll bar bolt, antenna continuity tests are all good now that I added the secondary nylon washer, and all that's left I believe is the radio. I was in a bad location but I seemed to be getting some truckers to come through on 19 every so often so I think I may have it working now.
|07-27-2011 03:19 AM|
|s3nt3nc3d||Thanks guys...will check things out tomorrow...didn't even think to check things at the radio end. D'oh!|
|07-27-2011 02:15 AM|
Definitely disconnect the radio before running resistance checks on the cable. The output stage on the CB can/will cause erroneous readings. Not to mention feeding a DC voltage into the antenna connector isn't very friendly to the radio.
PKB hit the high points. You're working the grounding issue at the antenna end, but you need to work it at the radio end as well. Does the CB have a ground stud you can use to ground the radio chassis?
73 N5VFF/YI9VFF - Brian
|07-26-2011 06:51 PM|
If I read you correctly: You are using an Ohm meter to measure resistance between the center conductor of the coax and the sheild of the Coax without the radio connected, Right?
If that is the case....There should be ZERO connection. Infinite. There should be no connectivity between the center and sheild of the coax/antenna.
I'd replace in this order:
1.> Antenna mount
BTW, I'm a ham.......
Hope that helps....
|07-26-2011 01:48 AM|
CB Issues - Need Troubleshooting Advice
I hooked up my cb recently... I've had a cb before so I know the basics on installation.
Wired up a taillight mount...ground off paint around all screws to ensure a good ground just like the 4x4explor how-to recommended (or maybe it was one of Stu Olson's write-ups?). Anywho... powered radio off cig lighter since I wanted it to go on/off with my ignition. I know it's not the cleanest power source and I don't run any high powered items off that circuit so I was willing to take the risk and use it.
When I tried to tune my antenna (3' Firestik, standard antenna stud/antenna wire)...my SWF readings were pegged and adjusting antenna length made no difference. I called my buddy who's a radio geek and asked him if he thought I had a grounding issue. Without using my ohmmeter to run any tests, I just went ahead and added a secondary ground wire from my mount to one of my rollbar bolts. SWR was still pegging and adjusting length made no difference.
This time I got smart and started troubleshooting with a meter...
I tested mount to ground - no resistance (good)
Tested base of antenna to mount - no resistance (not good)
During this time, I had also unhooked the antenna wire from the antenna. I found that my antenna was grounding out on the mount. The nylon washer I had was damaged due to the hole in the mount being a hair too large and the stud I believe was also damaged because the base of the stud was not insulated...so even though I was using the nylon washer, the stud was cocking sideways when I was tightening it down and it was pressing against the inside of the mount hole (thus grounding it out). I wrapped the stud in electrical tape to insulate it from the mount on the bottom (I didn't have any extra parts to work with) and then put the nylon washer on the top side to ensure it kept the stud from touching the mount up top. Tightened everything up, checked with the meter - overload/infinite resistance. Perfect. Went out and tuned the antenna. Kicked it on...worked great.
3 days later I went on a 300 mile trip to IL...cb worked for about an hour or so and then static. I just shut it off and said F it. Today I decided to start troubleshooting again... unhooked wire and checked antenna to mount/ground. It had again grounded itself out (I'm thinking due to moisture getting in there but not sure really). This time I had grabbed my old antenna stud from home so I used a nylon washer on the bottom AND the top to separate the antenna from grounding out on the mount. Checked with the multimeter and all is perfect. Hooked it up...still just static...I'm near enough to the interstate at work, I should be able to pick stuff up without any issues.
I also decided to check the resistance of my antenna...so I unhooked the wire and probed from center conductor wire of antenna to the outside of the connector. I'm showing fairly low resistance...the meter I have reads weird...but regardless, it's showing SOME resistance but not infinite resistance. Is this normal? The other end was still connected to the radio...so while connected would it show some resistance as opposed to infinite?
Just trying to get this damn radio figured out...kinda pointless to have it in there if it's just there to look pretty ya know?
I think one thing I need to do is replace the connector that goes on the bottom of the stud...pretty sure that's the main problem I'm having with grounding. Now I'm just confused as to whether all is normal or worse yet my grounded out antenna shorted my radio out when I transmitted on it during the short period of time it was working on my trip.