148 GTL New Style 4 Pin Mic. (Low Power)

[Low_Boy]

I bought this radio used and it worked good. I put it on a meeter to see what kind of wattage it was getting keyed up on Am showed about 15 PEP. Turned it to sideband keyed up and the needle dropped. No power no frequency on AM and Sideband. I was told to replace the voltage regulator I did and the radio showed frequency but no power. Replaced the final and I am now getting power and frequency but about 2.5 on AM and about 5 sideband. I was told a Cap. may have also went bad but all look good. Has anyone had this problem, Or know where else to look?
Thanks,

 

[loosecannon]

welcome to the forum.

kinda hard to tell whats going on from your description.

you say the radio worked good, but you'd never hooked a power meter to it so you dont know if it was always putting out 2.5 watts or not.

maybe you can describe in more detail what exactly happened to the radio and what the current status of it is.

help us help you.
LC

 

[Low_Boy]

I ran the radio for a day before I put it on the meter. It worked great. Had some long distance checks and the radio had good receive. When I put it on the meter it showed 15 PEP Am. when I switched it to SSB and keyed up that is when it went dead on me.

 

[radiohobby]

Do you mean you switched the radio to lsb or usb and keyed the mic and did not see any reading on the meter. If that is what you are saying that is normal. On SSB you do not put out power until you modulate the radio. You have to be making a sound into the mic to get power out of the radio.

 

[Low_Boy]

With modulation on sideband I only get 6 watts power on AM 2 watts dead key and 5 watts PEP. And noticed I have good modulation but can not calibrate my dosy meter when set to modulation. I turn the dial all the way to the right and the needle will not hit the calibration mark. But I do have all kind of modulation. at least 100%

Radiohobby--- I misunderstood your question at that point is where the radio went to hell on me and stopped working properly.

 

[radiohobby]

Are you getting those reading into a dummy load or into the antenna? For the most accurate reading for testing you should be going into a dummy load. Going into an antenna can make the readings look off by several watts.

I will have to see if CBtricks has any info on the new style 148. I still use the one I bought new back in 77 and it puts out a lot more than that for sure. Have heard the newer ones don't do quite as well though. Let me know if you were doing the testing into a dummy load though.

 

[loosecannon]

you say you replaced the final.

im wondering if you re-peaked the transmit stages after replacing the final.
it needs to be done.

im also wondering what part you replaced the final with.

in the new 4 pin 148gtls, the final is a CB-20W, and the driver is a 2SC2078.

it would be an easy mistake to make to look at a schematic online and accidentally be looking at the older 5 pin version.

if this is what happened, you probably replaced the final with a 2SC1969, which was probably a fake, as 90% of them out there today are.

the fakes give low power output.

so, am i on the right track here?
LC

 

[Low_Boy]

Radiohobi.... I am testing into a dummy load.
Loosecanon .. I did replace the final with a 1969. It is a real one though and some one gave me another real one in case the first one was bad and got the same readings. The Had a 2166 driver and a 1969 final. I replaced the driver with a real 2166 and also tried a 2078. I keep getting the same readings. Now I have all real 2166 driver and a real 1969 final. Like I said the radio was doing very good until this all happened. Some one said when the regulator and final went it may have took a Cap with it they all look good so I would not know where to start. Thanks

 

[radiohobby]

Best thing I can tell you at this point is to download the tech manual from cbtricks and run all those voltage checks. I think it is really for the older radio but maybe it will get you in the ballpark and help you narrow it down. Good luck and don't give up.

 

[Low_Boy]

I was hoping it would be easy...LOL or maybe someone would have said I had the same problem and all you have to do is change this or that. I will let you know if I get it working. I guess I will check voltages next. It may even be a bad regulator someone said.
I will keep you posted Thanks for the help.