Cobra 21X FM converstion to 40 Meters

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StormShadow
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Cobra 21X FM converstion to 40 Meters

Post by StormShadow » 17 Feb 2016, 14:06

Hi there, I had an old broken Cobra 21X FM CB radio so it was perfect for converting it into a 40 Meter LSB rig. Well there wasn't a lot to it really the first thing I did was remove any useful components from the main board like the xtal and a couple other little bits, so to cut it a long story short I removed the board, unfortunately the speaker was no good either so I had to find a donor CB, luckily I had a spare speaker in my junk box, the other down side is that it didn't have its power socket either otherwise I would have used that in my project too.

To get the CB from FM to LSB and drop the frequency from 27 MHz down to 7 MHz I just replaced the board with a 40 meter kit :D

I spent 1 night and one morning building this It didn't take me long to solder everything onto the board. The bit that took the most time was making everything fit the way I wanted, I had a bit of trouble getting the volt meter in where I wanted it to be, but the tuning cap was in the way so I had to find a way to make them fit together and after some thinking, with much cursing and cussing I got it done. I took out the red piece of plastic on the face where the channel display would be and replaced that with a piece of transparent blue plexiglass that I cut out as everything will light up in blue on the front. I also made it some feet out of 2 soda bottle lids. The L.E.D will be blue while on RX and turns red on TX. It looks a lot better off camera, my camera doesn't seem to like the blue lights. I know it looks bright but its just the camera.

I will be adding some modifications to it at a later stage, so there are some wires not connected to anything.
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Last edited by StormShadow on 18 Feb 2016, 11:54, edited 3 times in total.

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Crusader
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Re: Cobra 21X FM converstion to 40 Meters

Post by Crusader » 17 Feb 2016, 14:09

:lol: Now that is mad,wow some effort gone in there just to get on 80m even though it is just a 40m kit in a cobra chassis,but respect to you for building it,make sure you fit a roger bleep & echo just to keep them happy on 80m ;) seriously well done :thumbup:
Last edited by Crusader on 17 Feb 2016, 14:26, edited 1 time in total.

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Re: Cobra 21X FM converstion to 40 Meters

Post by Admiral » 17 Feb 2016, 14:21

Is the speaker shown the before or after version?
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StormShadow
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Re: Cobra 21X FM converstion to 40 Meters

Post by StormShadow » 18 Feb 2016, 11:58

That speaker was the only spare one I had. I do have 2 more CB chassis that will soon also be QRP Ham transceivers but I didn't wanna take the speakers out of them. I'm hoping to get something for 20 meters to take camping with me during the summer months.

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Re: Cobra 21X FM converstion to 40 Meters

Post by prettypolly » 18 Feb 2016, 12:38

im waiting for the jentec version ..

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Re: Cobra 21X FM converstion to 40 Meters

Post by Crusader » 23 Feb 2016, 23:20

prettypolly wrote:im waiting for the jentec version ..
:lol: Class :D

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