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Gonemuddin1
New member
Username: Gonemuddin1
Post Number: 8
Registered: 4-2005
| | Posted on Monday, April 11, 2005 - 11:51 am: | 
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I just got a '91 Cobra 29 LTD Classic and tested it, and found some problems. First off the Display doesnt work right, but that shouldnt be a hard fix. The other thing is that it recieves good, but when I try to transmit it wont. When I key the cobra another cb hears the click, but then the transmit quits on the other radio even while Im still talking on the cobra. My guess is maybe the final? I opened it up and found that D11 and D23 have been cut. I found that D11 increases modulation, how much and does it affect clarity or lifespan? Now I havent been able to locate what the cutting of D23 affects, could this be my problem? Any sugestions? |
Hotwire
Intermediate Member
Username: Hotwire
Post Number: 286
Registered: 1-2005
| | Posted on Tuesday, April 12, 2005 - 9:03 am: |
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My goodness! Dont let anyone cut anything else! Sounds like a bad final. Its an easy fix. Take it to a tech with a scope and get those parts put back in. Thats a fine radio. |
Gonemuddin1
Junior Member
Username: Gonemuddin1
Post Number: 10
Registered: 4-2005
| | Posted on Tuesday, April 12, 2005 - 10:10 am: |
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Yea, thats what I thought. I didnt cut nor wanted anythin cut, I just bought it at an estate auction and didnt really know what i was gona get. But I should be able to make my money back by selling the working ranger rci-2970 that I also ended up with. I paid 70 for the two radios, 5 mics, 5 antennas, 8 track player, and alot of other junk that came in the box. I believe I ended up with a deal even tho the cobra is broke. |
Hotwire
Intermediate Member
Username: Hotwire
Post Number: 289
Registered: 1-2005
| | Posted on Tuesday, April 12, 2005 - 10:45 am: |
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Sounds like a killer deal. The 2970 alone to me is worth more than 70. I would keep it! |
Muddierduck
New member
Username: Muddierduck
Post Number: 6
Registered: 9-2004
| | Posted on Tuesday, April 12, 2005 - 3:08 pm: |
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Thats what I was thinking Hotwire, $70.00 for a working 2970 is worth more to me. |
Gonemuddin1
Junior Member
Username: Gonemuddin1
Post Number: 16
Registered: 4-2005
| | Posted on Saturday, May 21, 2005 - 1:43 pm: |
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Does anyone know where I can get the LED Channel display for the Cobra? |
Bruce
Senior Member
Username: Bruce
Post Number: 2647
Registered: 9-2003
| | Posted on Saturday, May 21, 2005 - 6:24 pm: |
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Try Cobra not too many places to get parts. |
Yankee
Advanced Member
Username: Yankee
Post Number: 571
Registered: 7-2003
| | Posted on Sunday, May 22, 2005 - 12:38 am: |
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Try the different CB shops that might have a junk box, the Uniden AM radios that are the same would have the same LED. Never know what you're going to find. |
Gonemuddin1
Junior Member
Username: Gonemuddin1
Post Number: 17
Registered: 4-2005
| | Posted on Sunday, June 05, 2005 - 11:19 am: |
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Ive herd a couple people say that they have had the upper and lower side band installed on this model radio. They used the delta tune knob for the switch. What I was wondering was, does anybody know of a kit to do this and would it be worth while to do? No I am not interested in buying a new sideband radio; thats the reason I am asking this question. |
Patzerozero
Advanced Member
Username: Patzerozero
Post Number: 884
Registered: 7-2004
| | Posted on Sunday, June 05, 2005 - 10:31 pm: |
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they were using an 'expo a' kit. not sideband, but 40 channels immediately below 1 & 40 more above 40. copper doesn't sell 'em, but they're out there, about $30 & fairly easy to install if you're handy with a soldering iron & understand the inside of the radio. |
Gonemuddin1
Junior Member
Username: Gonemuddin1
Post Number: 18
Registered: 4-2005
| | Posted on Tuesday, June 07, 2005 - 1:09 pm: |
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Oh ok, I didnt reallize thats what they were talking about. Thanks for the help. |
Gonemuddin1
Junior Member
Username: Gonemuddin1
Post Number: 19
Registered: 4-2005
| | Posted on Thursday, June 30, 2005 - 10:19 pm: |
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One more Question, I seen several people recomend the 1969 Final for these radios. What kind of power gain can I expect for this mod, and where is the best place to get ahold of one. Also, I've seen so called "super mod" kits that apear to be only a capacitor soldered in near the final, what componets would I need if I wanted to make this mod myself. And I guess the real general question is what would yall recomend as good mods to this radio, I would prefer good sound quality so I dont think I want to go outrageous. Thanks for yalls help so far, this is by far the best site I have found for radio com. |
Gonemuddin1
Junior Member
Username: Gonemuddin1
Post Number: 20
Registered: 4-2005
| | Posted on Wednesday, July 06, 2005 - 11:17 am: |
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Any sugestions? |
Brewdirect
Intermediate Member
Username: Brewdirect
Post Number: 126
Registered: 7-2004
| | Posted on Wednesday, July 06, 2005 - 5:53 pm: |
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Don't bother with the bigger final in that radio especially since it's already so hacked up. I'd even replace some of those limiter parts. in most 29's you can get loud modulation with a resistor / capacitor modification without chopping up the modulation circuit.
If you need instructions for the resistor / capacitor mod let me know. You should see around 15-20 watts swing after the mod.
If there want more than $30 to fix up that cobra 29 I might pass. You can find em around in perfect used condition for $50. |
Gonemuddin1
Junior Member
Username: Gonemuddin1
Post Number: 21
Registered: 4-2005
| | Posted on Thursday, July 07, 2005 - 10:51 am: |
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Well Ive got it up and running now, it only cost me $20. I just want alittle more power out of, and amps are just out of my price range right now. As for the cap/res mods I would be interested in doing those, and I will solder the modulation limiter back up. Which caps/res are you talking about? |
Brewdirect
Intermediate Member
Username: Brewdirect
Post Number: 128
Registered: 7-2004
| | Posted on Thursday, July 07, 2005 - 5:14 pm: |
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This was some info I found....the capacitor/resistor mod is good for adding swing and modulation audio , BUT if you already have a radio that had the limiter taken out your audio and swing may already be loud..I'd pick up a SWR/Power meter before doing any more mods. This mod was designed to lower you deadkey for running an amp. In many cases in increases peak power from a stock 29..but if your radio was turned in the past it may already be exceeding these numbers..a power meter is the only way to tell.
______________________________________________
**How do I lower the deadkey for Cobra 29LTD Classic to run an amp? I have heard of a swing mod that lowers your deadkey, gives more swing and more audio?**
I'd do this for the amp, change the value of the resister to raise or lower dead key:
"Remove JP36. Install a 470uf 25v cap in it's place, negative side to the final. Where that solders in bridge a 100 ohm resistor. Tune the three output cores and adjust vr4 for audio. You'll have a 1w carrier, 18w of talk power, and no hacking. Go do all those fancy hack mods, "big final" and all that other •••• and you'll peak 20w instead of 18 and be muddy and distorted.
Use a 47 ohm if not running an amp"
**Where can I get the parts?**
Well all the parts can be bought from Rat shack, you will probably only find a 35volt cap, which will work fine. I use a 3kilowatt dummy load and a triple meter with power and modulation scales. I'll be honest with about lowering the dead key with pots, if your not sure what your doing you will screw up the shape of the signal, and this mod I posted is actually very easy to do, easier than the other way really and much better for driving an amp. Since you are lowering the dead key yet increasing the foward power, it really drives that amp hard the way it should for loud and clear audio. I have done it on a 25, but the jumper wire isn't the same location number it’s JP6, but it is the one right there in front of the final.
**Okay, ALL DONE !!!!! Only took 10 mins in all.....cleaning up the inside of the radio took 30 mins cause it was nasty and dirty...looks liked someone took a dump in there.
It's a 1995 model made in china.......currrently had a 4 watt deadkey...swing to 6-7.
I took out JP36...(had a tough time finding it...dirt was covering the label, it's towards the back of the radio on the left side..right next to L14).
I put in the 470uf cap(neg side towards the back of the radio...I'm guessing this was right??)....and then on the other side of the board I put in a 100ohm 1 watt resistor(someplace I read don't use less than a 2 watt resistor, but I could only find the 100ohm 1 watt and a 47ohm 5 watt). I had to cut it down good and bend it slightly to fit under the cover on the board side.)
I adjusted VR4 all the way up....
I plugged it in and....1 watt deadkey 12w swing....(this is with the stock mike)
I didn't adjust L14 at all yet....
Thanks all.....very happy with this mod.**
Tune it up! You should see about 20 watts PEP, and yes it's ok to swing that much into the amp, your carrier won't change, then you'll really drive the •••• out of that little KLV. Good job, told you it would be easy!
****NOTE when doing this mod you can also install a Potentiometer along with the resistor...this will give you an variable deadkey. Using the potentiometer you can set the deadkey to the lowest setting (which would be dependant on the resistor, or you can turn it up to full output.)****
TALKBACK MOD FOR COBRA 29LTD CLASSIC
**I need to admit this right up front. I have never opened a radio up before.**
With that being said, I saw a post where one could add talkback by adding one resistor somewhere to a speaker jack and a PA jack. IS this something I can do or am I just kidding myself?
just put a 47 ohm to a 100 ohm , from the speaker jack to the pa jack, if you look at the back of the radio on the soilder side. in the back of the radio were the jack is you will see the pins were the jack comes in the board put the resistor across that
I believe the resistor, or 100 ohm pot will work too, needs to be soldered across the ground leads of the EXT. SP and PA jack.
**WHAT IS THE DIFFERENCE IF YOU USE A 47-OHM OR 100-OHM DOES ONE OR THE OTHER MAKE IT LOUDER?SHOULD YOU USE 1/4 OR 1/2 WATT RESISITOR?**
the diffrence in the resistors will make it louder if you have the varible its nicer cause can adjust it
1/4 will do
The mod works for most radios, now lets say you don't have a pa jack... The resistor will then be from ext spkr jack to ground, this will work for alot of radios BUT NOT ALL AND THIS IS THE SAME FOR THE EXT SPKR AND PA JACK AS WELL, IT WILL WORK FOR MOST BUT NOT ALL THE RADIOS...
QUESTION: IF I DO THIS MOD TO MY COBRA 29LTD CLASSIC AND ADD THE TALKBACK....WILL IT DISABLE THE USE OF THE PA OR EXT SPEAKER
They will both be funtional.
If you want it just to check your mic then you might want to go the extra yard and install a switch so you can disable it. Fairly simple to do. Just run wires from the two jacks to the switch and have the appropriate resistor in line for the amouant of audio you want. |
