I'm trying to due a standard tune up. the radio won't transmit with the covers off. it will sometimes and sometimes it won't. this is a 2011 model cobra 148 gtl D. i'm thinking this might be a ground problem or i'm thinking i have a bad final or something else. help if you can thanks
I would say a bad or cold solder joint on board somewhere. Bad quality control. Might flex radio chassis slightly while keying? A tooth pick and hours of probing around switching area on board and the pa section till problem found.
Testimonial: "gave me somthing else to consider. radio did show sighns of not wanting to switch into tx mode. however with was able to atempt to tune with the radio putting out about 1 watt swinging to about 4 watts. quality control has been an issue with this new 148. thanks for your input"
On the 148 gtl sone body cut the pink wire on mic hai were does it go
SOURCE: cobra 148 gtl new model
Hello bluzfan, Do you remember the old 40 channel CBs? they used basic A3A transmission (dual sideband single carrier)remember how you got crosstalk sometimes, if your power was too high? Then they went to 80 channel CBs (using a single side band as Lower Side Band (lsb) and the other as the upper side band (usb))? more crosstalk but they invented anl (automatic noise limiter)circuitry to compensate. Now you have the 120 channel CB which uses a form of side band multiplexing (20QAM) to generate 3 times more channel density 40 X 3 = 120. Here is my problem; Cobra should not have done this because you will have massive crosstalk and unaudible sounds because of the increase in channels but not an increase in initial (physical)bandwidth. I hate to tell you this but the only cure for the is to use it in 40 channel or 80 channel mode forget the 120 channel mode, or get a radio with better channel separation.
SOURCE: cobra 148 gtl
Open the radio up and find the L22 Can/Pot. It's the one with the wire soldered on top. With both fine and coarse Claifier/Voice Locks in the 12 O'Clock positions, confirm, then listen for someone that is on the correct frequency and turn this pot (small ferrite core inside) with a small plastic preferred screwdriver, until they sound clear. Do this for USB as well except, the Can/Pot is L59. Don't adjust the VR5 (transmit) unless you need to.
SOURCE: cobra 148 gtl
First take a jumper wire and connect it to the DC Ground of the input of the radio then touch it to the TX pin on the radio if it does keyes up then its in the mic or mic cord on the end of the mic plug or where it goes into the mic cable goes up inside the mic. If the radio don't key up at all then check the main voltage regulator chip one pin will have 8 volts transmit and another pin will have 8volts recieve. If you get no switching DC voltage on the regulator then its bad and needs replacing there is also a known bad capacitor in the radio thats only 10 volts change it to 25 volts at the same capacitance.
SOURCE: 148 gtl
Hi Benimur, the only reason I chimed in on this topic is that years ago my CB shop did some testing on that antenna and a few others from Workman using a MFJ 269 analyzer. I seem to remember there being a coax chart available for CB freq's and also 10 meter freq's. There is no tuning adjustment on the ant itself, so there has to be some way for adjustments,, thanks, Mechanic
SOURCE: have a new cobra 148 gtl took out of box no transmit or recieve
make sure that your [swr] hadn't changed or went higher than a 1.5, anything higher will interfere with your tranmitting an recieving. other than that with out being there to see an hear your radio this would be the first place to start.
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