I need two of the adjustable coils for a Cobra 29 LTD St. I need L14 and L16. The slugs have been removed. Can I just get the Slugs somewhere? If not does anyone have part numbers for digikey or elsewhere?
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Cobra 29 LTD St parts list?
- Thread starter ClaimJumper
- Start date
If the cans are intact and just the slugs have been removed, you could just grab a couple of slugs from a parts radio and away you go.......
Are you sure the slugs are actually gone and not just crushed into the bottom of the can by someone's golden screwdriver ? I do wonder why someone would take them right out!
Not sure if those cans are still available new or if used is the only option nowadays.
Are you sure the slugs are actually gone and not just crushed into the bottom of the can by someone's golden screwdriver ? I do wonder why someone would take them right out!
Not sure if those cans are still available new or if used is the only option nowadays.
There's an old school mod that says to remove them. I'm assuming that's what was done to this. Maybe I can find the right size in another radio somewhere. It might not even be an issue if it Tunes up. I'm going to replace the final transistor, so I guess I'll see after that.
Maybe someone out there has those ferrite slugs listed for sale, but I haven't found them yet. The radio is sold with no slug in L16. Comes that way. The slug in L14 exists mostly so you can adjust the carrier down to the legal 4 Watts. Max output occurs with the slug removed, so now you know why it's missing. Extremists who want it to be adjustable will change the adjustment range of L14 by unsoldering it, unwinding one turn from the wire and soldering it back in place. This reduces the inductance so that turning the slug gives you the same effect but with the slug in place, not removed.
What replacement did you have in mind for the final?
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What replacement did you have in mind for the final?
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No slug? Okay. Well that helps out a lot. I guess I just assumed there was one missing when it wasn't there. Thanks for that info! The final I bought is the 2sc 1969 from HG. Haven't installed it or tested it yet. I got it from Fat Boy in New Jersey. That was one of the first places I found it at.
Also just for info.. I'm just trying to bring this radio to life right now. It was dead when I got it. I got everything going. It was actually throwing a carrier at four Watts, but absolutely zero modulation. Could not make a sound come out of it. The needle didn't even move. I went through hell trying to figure something out. Not sure if this is the fix for that or not but the final tab was shorted against the heat sink. Decided to replace the final all new. We'll see. I hope this fixes the modulation problem.
Hate to be the bearer of bad news, but the finals have absolutely nothing to do with modulation. The final amplifies the RF signal before it leaves the radio. That is all. No modulation will be an entirely different issue.
Does the radio have audio on receive ? Do you get sound through the PA speaker output ?
Stupid question, but did you try another mic ?
If the receiver audio is okay, the lack of transmit audio points to the mike circuit. Have you tried plugging a speaker into the PA jack to see if you have any mike audio keyed down with the PA selected?
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I have not plugged into the PA system. There is audio on receive. The microphone is brand new. I guess I'll plug into the PA after I put the final in. What should I look for at that point?
If there is audio on receive then we know the audio chip is good, as it is shared by both the receive and transmit audio.
Many of the components feeding audio to the PA are the same ones that feed audio to the transmit side of the radio, so having mic audio coming out the PA would be a good sign.
The chances of a brand new mic being dead are small but not unheard of, especially in this age of Chinese junk.
Question: Is it the right mic for the radio? Just because the plug works doesn't always mean the mic is wired for that radio! You say it's brand new....Is it compatible with that radio for sure ? Sorry for the dumb questions, but sometimes the simplest explanation turns out to be the correct one!
I will let Nomad chime in now as he is much more the expert than I am......
Many of the components feeding audio to the PA are the same ones that feed audio to the transmit side of the radio, so having mic audio coming out the PA would be a good sign.
The chances of a brand new mic being dead are small but not unheard of, especially in this age of Chinese junk.
Question: Is it the right mic for the radio? Just because the plug works doesn't always mean the mic is wired for that radio! You say it's brand new....Is it compatible with that radio for sure ? Sorry for the dumb questions, but sometimes the simplest explanation turns out to be the correct one!
I will let Nomad chime in now as he is much more the expert than I am......
It is specifically wired for this radio. If I yell into the microphone I can hear it on a different radio inside the shack very extremely faint. Can't make out any words. It does not move the needle though and it doesn't register on a modulation meter. I think it's just bleeding into the other radio because they're so close because nothing's going out the coax except carrier. And I can't get a damn signal check because I live in the middle of nowhere.
D11 is good. Adjusting V4 does nothing at all. When I'm done doing these other tests I'll probably poke around the mic input to the chassis. Wiggling it around and shaking the cord of the microphone.. none of that works.
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Ah, the mike doesn't have the word "electret" molded into the rear of the mike's case does it?
Can't remember a 29LTD model that uses that kind of mike. A radio that's meant to use an electret type feeds a small DC voltage up the mike cord into the element. A radio meant for a dynamic mike won't have this feature and an electret mike will appear to be dead.
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Can't remember a 29LTD model that uses that kind of mike. A radio that's meant to use an electret type feeds a small DC voltage up the mike cord into the element. A radio meant for a dynamic mike won't have this feature and an electret mike will appear to be dead.
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Okay. I just got the Cobra 29 back on the bench after finishing the Robyn. I hooked up a PA to it and I can hear myself through the PA perfectly well. So now I'm still at a brick wall. I just can't figure out why the audio isn't going through the antenna. This is a good, known to work, antenna. To anyone who hasn't read the whole thread.. everything seems to be working fine. I'm not getting any swing on the meter though, and there's no audio coming out of my receive radio. I can hear the noise if I yell into the mic, but I can't make out any words. VR 4 doesn't do anything at all! D11 tests good in the circuit board. I'm thinking of removing it and testing it though. Anybody have any ideas?