Just added the 2030 final to a 2005 Cobra 29 NW ST (PC Board 060-J). However it made no power improvement, Just to be sure, replaced all 3 componets with another set, same results. Have these newer radio been choked down in some other way? Does anyone have an idea?
Thanks in advance,
73's
2005 Cobra 29 NWST Modulation Problem on TX / PA
2005 Cobra 29 NWST Modulation Problem on TX / PA
Last edited by RedEye on Sunday 23rd Dec 2007, 16:11, edited 1 time in total.
Update, I think the problem is with modulation. It is a new radio, never modded, however audio is very low on TX and on PA. I can even jump pa/ext together WITHOUT a resistor and there is no feedback, very low talkback.
D11 still intact, tried it also with D11 open no difference in modulation..
I also noticed when keyed it makes a loud pop just before mod gets quiet. The "pop" make the mod meter bounce before any modulation is started...
While waiting, I just tried a known good audio chip, no difference....C48 ok C45 OK
Any thoughts were to start looking?
Thanks again!
D11 still intact, tried it also with D11 open no difference in modulation..
I also noticed when keyed it makes a loud pop just before mod gets quiet. The "pop" make the mod meter bounce before any modulation is started...
While waiting, I just tried a known good audio chip, no difference....C48 ok C45 OK
Any thoughts were to start looking?
Thanks again!
Re: Cobra 29 NWST Modulation Problem on TX / PA.
Is this the radio which 2 ICs on the input side of the AF amp, I think they are IC801 and IC802. I ask this question as I do not have a Sch diagram for this one.
Have you check the Dyanmike pot and the caps around TR17 and TR18.
Have you check the Dyanmike pot and the caps around TR17 and TR18.
Rick.
Re: Cobra 29 NWST Modulation Problem on TX / PA.
I think it would be best to start a new post in CB Radio Repair and Troubleshooting, as this post is in the wrong part of the forum.
I assume this RX is ok?
If so then the fault is most likely be around TR17 Mic Amp and TR18 AMC.
You can check the AMC by unsoldering the collector of TR18, see if the audio is now ok
What voltages do you have around TR17 and TR18?
His this one of the Cobra?s which is using 1/16 watt resistors if so check them as they are known to give trouble.
I assume this RX is ok?
If so then the fault is most likely be around TR17 Mic Amp and TR18 AMC.
You can check the AMC by unsoldering the collector of TR18, see if the audio is now ok
What voltages do you have around TR17 and TR18?
His this one of the Cobra?s which is using 1/16 watt resistors if so check them as they are known to give trouble.
Rick.