cobra 29 deadkey/swing mod

[WESTGATE]

im trying to lower the deadkey , ive used the cap/resistor mod before with variable power too..but does anyone have a better idea on lowering the deadkey? i was thinking of doing that mod but instead just leaving the capacitor out and replacing the jumper with a resistor, but then i was thinking that maybe just adjusting L14 down to 2 watts or so might work?the thing that i can see would be kewl is leaving JP36 jumper soldered in at one point and a resistor soldered in with a leg up on the resistor and running a wire from the jumper and resistor to a switch on the front panel to kinda make a high/low power deal...i can swith the power to high and it will be like if the jumper was in place and the radio is stock, and switch it to low and it will be like the resistor is in place....so anyone got ideas?

[Night Crawler]

the thing that i can see would be kewl is leaving JP36 jumper soldered in at one point and a resistor soldered in with a leg up on the resistor and running a wire from the jumper and resistor to a switch on the front panel to kinda make a high/low power deal...i can swith the power to high and it will be like if the jumper was in place and the radio is stock, and switch it to low and it will be like the resistor is in place....so anyone got ideas?

That would work.

If you want a variable without the swing use this without the 100uf capacitor
TIP-120 mod [Please login or register to view this link] the #3 wire would go to side of JP36 that positive side of of the capacitor was to connected to and the #4 wire would go to where the negative side was connected.

A switch could also be used with it so you adjust the power level where you want it on low and be able to switch to high.

I wouldn't adjust L14 to lower the output.

[WESTGATE]

sweet .so....simply put,removing JP36 and replacing it with a resistor will lower deadkey?

[TheCBDoctor]

sweet .so....simply put,removing JP36 and replacing it with a resistor will lower deadkey?

Hi,

Without the cap you will lower the dead-key and lose forward swing. The cap is needed to keep the peak power high. You can put a switch on the cap and have the best of both worlds. If you are not using an amp there is no advantage to lowering the carrier. If you are using an amp you will want to use that cap.

Respectfully,

[WESTGATE]

awesome thanks doc...yea imma be using an amp...so use the cap ay? alrighty....i definitely wanna use a switch so i can use the radio barefoot .. thanks man

[WESTGATE]

another quick question....im hoping someone can kinda tell me what the JP36 jumper does and whats going on there.....and if a long wire run from a resistor/capacitor mod up to a switch on the radio front panel would affect anything or that length of wire wouldnt matter..? thanks

[WESTGATE]

oh and how about L14? can that be removed for higher deadkey or would leaving that alone recommended?

[Night Crawler]

im hoping someone can kinda tell me what the JP36 jumper does and whats going on there.....and if a long wire run from a resistor/capacitor mod up to a switch on the radio front panel would affect anything or that length of wire wouldnt matter..? thanks

JP36 is used as a test point to measure the current going to the collector of the driver.
The jumper would be removed and a meter used to measure current would be inserted there.

The trace going to JP36 is coming from the modulation transformer carrying the audio and voltage to the collector of the driver so if using a switch I would use 2 conductor shielded wire and make the length as short as possible.

oh and how about L14? can that be removed for higher deadkey or would leaving that alone recommended?

I would adjust it according to the service manual.

[WESTGATE]

cool thanks man....im actually doin this on a uniden pc68xl, but i said cobra 29 cause its the same deal....i found uniden 68's for 65 bucks free shipping online so i got one...and from time to time they have pc78xl's for 69$ free shipping