Hello, i have a new old stock cobra 142 base, i hooked it up and it worked great, i used it for a few mins, checked to see if sideband was on freq, and i lost recieve," i see recieve on meter," i get transmit, and no its not on pa, it also gets no recieve with extrenal speaker,
i also checked the mic, all mics including stock mic work but no audio on recieve, it happend so quick, any ideas for a quick fix, i have a bunch of donar radios i can take patrs from.
any ideas would be appreciated,
Nicky, Cleveland Ohio
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Try resetting the radio per the user manual by doing a setup procedure as described on page 28. This may clear up the problem. User manual here: https://www.cobra.com/sites/default/files/manuals/MRF75D%20-%20ENGLISH_0.pdf
just have to wrap a bit of tin foil over the bottom of one battery and use normal nimh rechargeables. The Cobra's have a seperate circuit that must be made to differentiate between normal AA and rechargeables. The OEM battery has an exposed metal ring on the bottom of the battery. If a normal AA is put it and allowed to attempt to charge, it will start a fire. If you look, there is one contact at the negative end of one battyery that must be made for it to allow to charge in the base. You could scrape away the plastic, but a wrap of tin foil did the trick for me.
You can ground both the antenna mast and the antenna. your best bet is to place an 8ft grounding rod in the ground from radio shack or local two-way radio shop. Then connect the grounding rod to your mast. You can get a polyphaser from your local two-way radio shop this will connect between your antenna and the radio. it will also be grounded to the grounding rod. This should leave you in pretty good shape.
I don't know this radio individually, but heres the common thing that happens:
Sounds to me like the 8 volt regulator chip has blown after overvoltage. I expect the power supply has gone too, putting 18+ volts into the radio.
Repair the power supply. (Check its 13-13.8 Volts).
Then check the regulator (7808) is putting out anything, should be middle pin ground then 13V one side and 8V the other, if nothing, its blown. Replace it if gone.
Hopefully thats all thats gone and it should work again.
If you antenna SWR are way out ( too high ) you may have burrned the final or driver up when you hooked it up to do the antenna adjustment. Also be sure to turn the high power switch on to adjust the antenna SWR or the SWR meter won't read correctly, if the RF power is too low. Good Luck
Hello, There is not compability issue, sounds like you have a mic problem because you hear the Roger Beep and that means that the transmition and Reception cicle is working if you could test an audio accesorie would be great.
There is another possibility if one of the radios is out of frequency you could experiment the same symtoms.
Double check against all the instructions - in particular, make sure the batteries are charged according to "before first use" spec, that the volume is turned up, and that the squelch (if fitted and not automatic) is adjusted properly.
If it still doesn't work, take it back to Wal-Mart.
If the product doesn't work, there's no need for the packaging to be in good condition - it's not as if they'll be needing it to resell the goods to anybody else.