COBRA 25 RFX 150 MOD
COBRA 25 RFX 150 DRIVER

If you had problems like the hum you could have backed out the 2 screws holding it in and touched up the solder points of the transistors with a pinpoint soldering iron and eliminated it possibly. As long as you tied the wires up and kept them up and away you should have left them alone and kept them factory length. I know you made the wires as short as possible but that may be a downfall to any repairs that could be made without completely removing it.

COBRA 25 RFX 150 DRIVER

If you continue to have the hum at any point then look to the driver and final in the RFX there is a quality issue there with the soldering of the pins of the transistors to the board. Heck for $40 and getting 4 times the PEP power out of the radio and it will sound crystal clear and awesome. If you installed the Cap and resistor at JP36 then remove it and run it without it, otherwise it will sound like crap. If you run it at 13.8v and set the dk to 12-15w(max) then it will hit around 75-80w. Either your meter shows happy watts or something is off because 150w is an unrealistic number for that radio or any other radio. Your dk is way to high and what voltage are you running it at. Mchaos the original set of RFX that came out with no pre installation check list and it was hit and miss on figuring out the problems. With a modded RK56 its sick.ДЄfter the slight difficulties, its one mean barefoot duck stomping machine. more swing, but raspy.ДЄt about 3/4 on the mic gain produced devilishly loud audio. If I brought it any lower then 20 watts the audio started to suffer and got raspy. Could probably go a bit more on the carrier, but that's where I got the best forward swing without sacrificing audio. I found that good forward swing was achieved at around 23-25 watts. Once I got far enough away to observe the swing, it was swinging back quite a bit.

Had a buddy of mine key it up, with out any swing mod. I found that with out dropping the dead key produced some back swing.

COBRA 25 RFX 150 MOD

I did tweak it using my mod meter but found turning it way down still produced full swing on the meter. Haven't seen anything else around on the net about this issue.ДЄlso, with tweaking I was able to get just over 150 watts pep out of mine dead keying about 23-24 watts. Might have been an issue with this particular cobra 29. Grounding the audio transformer pretty much took care of it. I also went around the radio and made sure all the ground points where good. I grounded the audio transformer to the chassis. I made sure to make all wires as short as possible. If any one has this problem, this is what solved it for me. If I turned the gain up past half, I had issues. There is a pre-installation guide, which has things to look for that will cause it not to work, that you can fix before install, and a troubleshooting guide. On the RFX75 page on cbtricks, there are 2 very handy documents that can help with them not working when new. I had some slight problems at first, but was able to work them out.ДЇirst I would like to through out an FYI.

Cobra 25 rfx 150