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realistic navaho trc 490

donemad

Active Member
Jun 21, 2008
104
1
26
i just changed the final to nte-152, but , it still about half watt & mod. backwards......can anyone help me....???????? thanks
 

What kind of amplifier is the TRC-490? I have never heard of that model number. If this is a radio you might try posting it in the cb section or radio mods section, you will get more people looking at it that way.
 
Assuming that NTE part is the correct replacement part, it sounds to me that your driver is out as well. OR - that the bias needs to be adjusted on both the driver and final transistors. Another possibility is that there is a diode somewhere in the output that has failed as well.

I would surely check the biasing of the driver and the final - first - IMO. Generally speaking, when you see backwards modulation on the output, it is because the driver or the final bias is set too high. This can also quickly burn them out once again. I am new to working on radios; but that has been my experience...
 
The right replacement would be would be nte 236 or 2sc1969 or 2sc1307 or 2sc2312 this is the same as the newer uniden washington radio pcb is 385 i think nte 152 is a good replacement for the main regulator on the back right side the final is on the back towards the middle of the radio i would suggest spending the money and puting in a 2sc1969 as the nte parts sucks i have also herd that you can use that cb20 replacent part and they seem to work ok and are cheaper i have used 2 and they worked fine for me but you might have to turn down the milliamps on the final biasing pot john.
 
Assuming that NTE part is the correct replacement part, it sounds to me that your driver is out as well. OR - that the bias needs to be adjusted on both the driver and final transistors. Another possibility is that there is a diode somewhere in the output that has failed as well.

I would surely check the biasing of the driver and the final - first - IMO. Generally speaking, when you see backwards modulation on the output, it is because the driver or the final bias is set too high. This can also quickly burn them out once again. I am new to working on radios; but that has been my experience...

agreed.and after checking this out there should be tuning slugs/cans to transmitting
many people set these up for max dead key.when this is done this usually causes
backwards swing from what ive seen.set these for max PEP/SWING not dead key
you should have a vr for your dead key use this to set carrier.id set it up
with a max carrier of 3 watts and let it swing.the tuning slugs/can are normally marked
like L-9 or L-5 check cbtricks.com they might have these listed
 
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