-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Trouble with Cobra 2000
- Thread starter Eastside
- Start date
If those two VR's don't do anything, TR24 had been removed. Replace TR24 and that will restore your adjustability of the VR's. Outside of that, its possible that the radio is out of alignment, and will need a transmit alignment.
~Cheers~
~Cheers~
If it is missing; then it will need to be replaced with a 2sc945. That is a very common part found in most CB radio chassis. If it is missing; then take one out of an old, junker radio. There is a flat side on the transistor; just line up the flatside with the silkscreen marked on the board where the original part was. You will see it on the board at the tr24 location. Easy as pie; piece of cake.
The radio seems to be transmitting and receiving on freq....i am going to check tr24
To disable the AMC/ALC for that hot raspy big dog modulation.... same thing as clipping out the diode on many AM radios, bad idea.
This is what some hackshack shops consider a "tune up".
73
This is what some hackshack shops consider a "tune up".
73
Usually, because they think it is a mod. For just AM use, it is. But it comes with consequences. First, it make SSB nearly impossible to use, as Xit13 described. Once tr24 is out of circuit, there is no regulating SSB because the AM Limter/tr24 not only regulates AM modulation, it is also joined/linked to the ALC circuit. Once it is removed, neither circuit will work as designed.
Ya know, if it was just an AM only radio that would be bad enough. But by removing it, it just makes it usable on AM only. Doubtless, some will disagree because they hardly ever use SSB so they aren't really aware. Or they know and simply don't care. Whatever. There are guys that I hear on ch 38/LSB sometimes during skip that have done this mod to their radio, and I tell them to put their AM Limiter back in because their radio sounds like squat. Very distinct, recognizable crap. Makes them sound really nasty and hard to understand.
There are better means to get more modulation; if 100% isn't enough. Xit13 came up with a mod that doesn't mess with SSB and produces more than 150% AM modulation w/o removing the AM Limiter. It is here somewhere on the forum if you look. Haven't done it yet myself; but Xit13 knows his stuff and I don't doubt him for a second, since I use SSB 99.999% of the time.
Last edited:
It took me awhile but i found where if was supposed to be...yup its gone....whoever took it out was good at soldering....looked like one was never there.......taking tr24 out makes your ssb so it only puts out 6 watts?
What's wrong with that? I remember the thread, and there were no flat tops or pinched carriers.
No; but it will make the radio impossible to align the SSB/ALC control as well as hard to control AM peak modulation. I've replaced every single AM Limiter that was removed from all the radios I got used and have never looked back.
Check the setting of vr10. But chances are, since someone has already gotten their golden screwdriver in there (evident with the removal of tr24), then they may have also volted the final, turned down vr10, and changed the values of some other parts as well (some caps and resistors). Depends who was in there and how much he changed. Try turning vr10 up for 4w/dead key on AM for starters; that should bring up the swing some too.
You also need to gauge PEP with an accurate meter . . .
Last edited:
6 watts is the best it will swing on am.....no matter where vr 10 is set.......which is strange.....the silver eagle is a very loud mic.
There are few things to check. First would be to go online and look and see how they were hacked and then unhack it. Do it all of the time. This would be the most popular way these radios can be hacked:
Cobra 2000 BIG AUDIO!!! at silicon two one two dot org
Just reverse what you find.
One other thing is to check the peak of the transmit coils by re-peaking them. But I would unhack as much as I could find in the radio - first. Some mods on these radios are OK to do (schottly diodes, hifi caps, a few others); but not the hacks for more modulation; these radios do not need help in that area. It is also an old radio, and one must also consider the state of the electrolytic caps; especially all of the 10v rated ones.
Cobra 2000 BIG AUDIO!!! at silicon two one two dot org
Just reverse what you find.
One other thing is to check the peak of the transmit coils by re-peaking them. But I would unhack as much as I could find in the radio - first. Some mods on these radios are OK to do (schottly diodes, hifi caps, a few others); but not the hacks for more modulation; these radios do not need help in that area. It is also an old radio, and one must also consider the state of the electrolytic caps; especially all of the 10v rated ones.
- No one is chatting at the moment.
