[Solved] Trying to make sense of this 89 XLR swing mod to use on my 21 XLR

[doffo]

Hello,

I have a 21 XLR I was wanting to try out the swing mod, but I am struggling to make sense of the instructions that I found on an old forum post. This is it:


I don't have my 29 XLR radios here with me, but figured the 21 XLR can also be done. As far as cutting the trace, Is this the place to do it? I attached the picture with the red line on if the cut needs to happen there..

The way on how to put in the capacitor also doesnt seem clear. Also, the clipping of d14 and jumping d11 seems like that is defeating the AMC limiter? If so, I do not wish to do that as I don't want to be splattering.

Any help on how to go about this would be greatly appreciated. I know that any Cobra GTL/LTD would probably be a better radio to do it to, but I just wanted to get it to work on this 21 XLR. Thanks for reading.

 

[doffo]

I eventually figured it out, but after the mod, it basically isn't worth the effort or time. Using a 100 ohm resistor was too much as it brough it down too far below 1 watt carrier, so using a 60 ohm 1 watt brough it to a 1 watt carrier. Modulation was a dog so it only got about 4-5 watts during the peaks. Included the pictures just for reference. Negative side of the cap goes to L15.

 

[Uncle Ronnie 336]

you should peep the pinned thread about the more involved swing mod using a TIP142 darlington upstream from the mod transformer. standard cap/resistor mods to do this thing square and pinch off a lot quicker and easier on the scope than on later cobras. the 1st radio I tried it on was a zachary T which is basically an 89/29 xlr

 

[doffo]

you should peep the pinned thread about the more involved swing mod using a TIP142 darlington upstream from the mod transformer. standard cap/resistor mods to do this thing square and pinch off a lot quicker and easier on the scope than on later cobras. the 1st radio I tried it on was a zachary T which is basically an 89/29 xlr

I will have a look. Thanks for letting me know.