Cobra 29 LTD FM mods?? Stumper of the century?

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raven666
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Cobra 29 LTD FM mods?? Stumper of the century?

Postby raven666 » Wednesday 7th May 2008, 10:25

1. Any ideas on how to get the radio into an FM mode that might be switchable? I know that you can pull the line from the mic and it goes somewhere around the crystal circuit to make it go FM.

2. Anyone know the secret of the PLL chip and the extra channels?

raven666
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Postby raven666 » Thursday 8th May 2008, 6:33

Ok - I found the PLL chip in the Cobra 25's and 29's is a turd that you can't do much with aside from excite the receive. Still working on the FM part.

RedEye
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Postby RedEye » Thursday 8th May 2008, 14:47

Both the 29 and 25 (US ver.) have an am audio chip, you cant pull FM without more mods than cost making it worthwhile. It might be useful overseas, but not a ton of action here in the states....

Rick would know the way to do it though!
Last edited by RedEye on Friday 9th May 2008, 1:10, edited 1 time in total.

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Rick
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Re: Cobra 29 LTD FM mods.

Postby Rick » Thursday 8th May 2008, 19:49

It is easy to add FM to most radios using a 455 KHz IF.
You just need a 455 Mod-demod module which can be obtained from Spectrum Communications www.spectrumcomms.co.uk/cbkits.htm#FM455

If you have any trouble, obtaining one from Spectrum, let me know as I think I still have one in stock.
Rick.

raven666
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Re: Cobra 29 LTD FM mods.

Postby raven666 » Tuesday 13th May 2008, 15:28

Rick wrote:It is easy to add FM to most radios using a 455 KHz IF.
You just need a 455 Mod-demod module which can be obtained from Spectrum Communications www.spectrumcomms.co.uk/cbkits.htm#FM455

If you have any trouble, obtaining one from Spectrum, let me know as I think I still have one in stock.


Thanks for the info. I am still trying to get through the 2030 mosfet mod. After about 100 swear words I made a $100 paper weight. Mine has the symptoms of some others I have seen here in the other threads. Wish someone would write a clear neat way to get this mod done successfully. 1-6watt is boring and I had 6 watt before I started on the stock final.

KC7NOA
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Re: Cobra 29 LTD FM mods.

Postby KC7NOA » Wednesday 30th Nov 2011, 14:31

Rick wrote:It is easy to add FM to most radios using a 455 KHz IF.
You just need a 455 Mod-demod module which can be obtained from Spectrum Communications http://www.spectrumcomms.co.uk/cbkits.htm#FM455

If you have any trouble, obtaining one from Spectrum, let me know as I think I still have one in stock.



Still have that FM455? Or a schematic?

camila
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Re: Cobra 29 LTD FM mods?? Stumper of the century?

Postby camila » Friday 5th Sep 2014, 16:54

I'm having the same issue. It's too high pitched. Did you ever figure anything out?
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