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cobra 90 ltd

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red bug
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cobra 90 ltd

Post by red bug » Sunday, 28 July 2013, 15:35 PM

hello all.
i have an older cobra 90 ltd. it keys 1 watt and swings to 7 watts. by the way it is a base station. how do i turn up the watts on this radio so i can run a hd 250 boomer?
the mod diode has been clipped, but i cannot find any information on how to turn up the output watts.
thanks :?:


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Re: cobra 90 ltd

Post by MDYoungblood » Sunday, 28 July 2013, 18:55 PM

Hello red bug,
Welcome to the forum. Here are the tuning points for your radio, Cobra 90 LTD, L303, L304, L305 are for AM power and RV201 is for modulation, if the diode has been cut it won't adjust anything. You aren't going to get much more than 5w DK and swing 10w, that is not a big power radio but it can run the HD Boomer amp. Get a power mic and reconnect the diode, the radio will sound better in the long run.

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red bug
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Re: cobra 90 ltd

Post by red bug » Monday, 29 July 2013, 9:24 AM

thanks greg.

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Re: cobra 90 ltd

Post by Z-MAN » Friday, 02 August 2013, 6:54 AM

I have an old 90 ltd with a blown chip, anyone know where i can get one? I remember many years ago it was doing the same watts as other Cobras, i would love to fix it back up.
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sonoma
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Re: cobra 90 ltd

Post by sonoma » Friday, 02 August 2013, 8:41 AM

what is the chip that is blown. the radio has a lot of chips in it?

August 02 2013
red bug wrote:hello all.
i have an older cobra 90 ltd. it keys 1 watt and swings to 7 watts. by the way it is a base station. how do i turn up the watts on this radio so i can run a hd 250 boomer?
the mod diode has been clipped, but i cannot find any information on how to turn up the output watts.
thanks :?:

here is the service manual for the radio.

http://www.cbtricks.com/radios/cobra/90ltd/index.htm" onclick="window.open(this.href);return false;


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Z-MAN
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Re: cobra 90 ltd

Post by Z-MAN » Friday, 02 August 2013, 12:28 PM

Audio i think, no rx or tx. No pa either, just a dead radio. I will take the lid off this weekend to get the #'s.
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sonoma
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Re: cobra 90 ltd

Post by sonoma » Friday, 02 August 2013, 17:33 PM

I posted the service manual just above. it has all the part numbers in it.

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Re: cobra 90 ltd

Post by Z-MAN » Sunday, 11 August 2013, 14:53 PM

Thanx, i just bought it from Dodgem's site, $12.50 audio ic, KIA 7217ap
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Re: cobra 90 ltd

Post by Grinder74 » Sunday, 11 August 2013, 15:19 PM

I would check for leaking/shorted caps before I change chips. I had a President Jackson that was DOA, I replaced the large caps where the power comes in and that fixed the problem. I could see they had leaked and were shorted.

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sonoma
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Re: cobra 90 ltd

Post by sonoma » Sunday, 11 August 2013, 20:04 PM

I* would change all the 10 volt caps to 16 volt or larger to enhance the performance and not have a chance to burn up the new chip. the 10 volts are so old they go bad. most of them are in a 8 volt circuit and the radio pushes that voltage and causes them to go bad.

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Re: cobra 90 ltd

Post by Z-MAN » Monday, 19 August 2013, 11:20 AM

Okay, i replaced the audio ic, i have PA now but no rx or tx. TX led lights up but nothing on the meter. I will inspect the caps.

Monday, 19 August 2013, 13:39 PM

The large cap, 3300uf 35v is cracked and leaked. Thanx for the heads up, i will replace it then post back. Radio looked a little dim when it was on, but it wasnt on very long though after i tested the PA.

Monday, 26 August 2013, 14:58 PM

Replaced the blown cap, no RX/TX yet but since the PA works, im guessing the driver and/or final trans. is blown too. Off to order more parts, lol.
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