Need some help with my Cobra 29 LX and AMP

[ztothej]

Hey Guys,

New here and sort of new to "tweaking cb's"

I have a couple questions and hope you guys can help..

First off I just got my amp in, its the new KL 203P and plan on hooking it up to my Cobra 29 LX.

The only this is I'm not to sure how to lower the output of the Cobra so its in the range of the amp.

The Cobra has been tuned by the shop I got it from and puts out about 30-35 watts.

The other option I have is to take the bone stock one I have in my motorhome and tune down the watts in that one while running the amp on this Cobra.

I hope I gave the correct information for some help, if not let me know and ill do my best to add in what is needed.

Thanks Sean.

 

[ztothej]

also can I take one of the RF switches from an older 29 Classic and use it for a power adjustment? if so will it lower the dead key to run the amp on the I can turn it up and not run the amp?

Id rather add a knob the hack up the factory one.. course if thats what it will do is lower the dead key..

 

[Wire Weasel]

Hi guy, several things

No your Cobra LX is not swinging to 30-35 watts. They won't come anywhere close to doing that much.

Your local CB shop has a "happy" meter that has been turned up. That is the one he shows the customers to show them how he gets a single final CB to do 35 watts and how great he is. We have a guy like that over in this area by the interstate who rips off the truck drivers.

Do you own a set a decent meters? Maybe you ought to get a set and check that radio yourself.

The power adjustment is in the back of the radio right across from the final and is that big barrel with copper wire wrapped around it and a big plastic slug screw that you turn. You need to get your dead key down to no more than 4 watts for your amp. 3 or 3.5 watts might be better.

Add a fan to your amp if you're going to do a lot of taking or it will overheat.

Good luck

 

[ztothej]

Hi guy, several things

No your Cobra LX is not swinging to 30-35 watts. They won't come anywhere close to doing that much.

Your local CB shop has a "happy" meter that has been turned up. That is the one he shows the customers to show them how he gets a single final CB to do 35 watts and how great he is. We have a guy like that over in this area by the interstate who rips off the truck drivers.

Do you own a set a decent meters? Maybe you ought to get a set and check that radio yourself.

The power adjustment is in the back of the radio right across from the final and is that big barrel with copper wire wrapped around it and a big plastic slug screw that you turn. You need to get your dead key down to no more than 4 watts for your amp. 3 or 3.5 watts might be better.

Add a fan to your amp if you're going to do a lot of taking or it will overheat.

Good luck

Thank you for your help, I figured something was up because I do have a SWR/ Power meter and Ive never seen 30-35 on it.. anyways.

I keep hearing about this "final" not to sure what or where it is on the board. I know its in the back just not sure what part is it.

So if I'm reading this correctly there s screw inside the final I turn down for the input watts that will go into the amp or is that to set the dead key??

In order to run this amp I've been told I need to have 15 watts into the amp with a 2 watt dead key.

If thats part you were talking about is the power adj. can you explain what the modulation (VR4) does??

Sorry for the questions, just want this amp to run good with the radio and be nice and clear sounding.

However I do have a meter and a left over Cobra 29 Classic that I can use for parts..

Thanks Sean

 

[Robb]

Adjust L 10 until you get 1 watt output dead key with the mic gain turned all of the way down. DO NOT adjust L 20; that is the 54MHz trap coil!!! Your RM Italy amp likes a low dead key. They will get damaged if you input much more than that.

KL203 Amplifier

http://www.cbtricks.com/radios/cobra/29ltd_29ltd_st_29wx_st/graphics/cobra_29ltd_sm.pdf

 

[ztothej]

Adjust L 10 until you get 1 watt output dead key with the mic gain turned all of the way down. DO NOT adjust L 20; that is the 54MHz trap coil!!! Your RM Italy amp likes a low dead key. They will get damaged if you input much more than that.

KL203 Amplifier

http://www.cbtricks.com/radios/cobra/29ltd_29ltd_st_29wx_st/graphics/cobra_29ltd_sm.pdf

Ok cool, what about the out put? how do I tune down the watts going in to the amp to a more suitable watt?

also my Modulation is set to 100% right now.

 

[Robb]

Ok cool, what about the out put? how do I tune down the watts going in to the amp to a more suitable watt?

also my Modulation is set to 100% right now.

The radio output is set by L 10.
Adjust L 10 for 1 watt output - or even 1/2 watt output if it will adjust that low. That amp will work at 1/2 watt; so that is where I would set the radio output for that amp. It will sound cleaner and run cooler that way.

 

[ztothej]

Thanks for all the help, still working some bugs out but otherwise all good..

I've been thinking about just buying a Stryker Radio and using it on CB.

I know the newer one puts out close to 100 watts.. so that will be good and close to the amp.. ( I think)

If I do get the Stryker I won't be running the amp on it, what does everyone think of this?

Sean

 

[Wire Weasel]

That is always your choice. Use a higher power radio by itself or a lower power radio with an amp. Lot's of folks do it both ways (one or the other).

Choose depending on your needs and finances.

 

[ztothej]

That is always your choice. Use a higher power radio by itself or a lower power radio with an amp. Lot's of folks do it both ways (one or the other).

Choose depending on your needs and finances.

Ok sounds good, ill keep working with the Cobra 29 LX and the 203P

What I can't figure out is when I click the "Pre" switch on the amp doesn't that help it receive better?

If so when I click it on the receiving goes away.. can't figure this one out.

 

[psycho]

Ok sounds good, ill keep working with the Cobra 29 LX and the 203P

What I can't figure out is when I click the "Pre" switch on the amp doesn't that help it receive better?

If so when I click it on the receiving goes away.. can't figure this one out.

The preamp is inoperative, but they are a complete waste in mobile applications anywho.