Cobra 148 is only putting out 2 watts on SSB?

[Eastside]

Any ideas what is wrong?

 

[Eastside]

AM works fine......the radio does not looked like its been messed with.

 

[9C1Driver]

Try turning VR11 up. If that does not work it's radio tech time.

 

[Eastside]

Try turning VR11 up. If that does not work it's radio tech time.

First thing I tried.....nothing.

 

[psycho]

First thing I tried.....nothing.

The obvious follow up question would be......Is the AM output OK?

 

[Eastside]

The obvious follow up question would be......Is the AM output OK?

Yes.....its putting out 4 watts on AM....will max out at 5 watts.

 

[9C1Driver]

Yes.....its putting out 4 watts on AM....will max out at 5 watts.

That seems low. You should be able to dead key 2-5 watts and swing 10-14 honest watts. SSB peak should be 16-18 quality watts.

 

[Eastside]

That seems low. You should be able to dead key 2-5 watts and swing 10-14 honest watts. SSB peak should be 16-18 quality watts.

This one is bone stock..no mods...nothing clipped.....just something wrong with the ssb...

edit.....I was going by what the guy I got it from told me....I was just looking inside it and noticed someone has been inside it...r131 is clipped.....but tr24 is still intact.

 

[KM3F]

How are you measuring SSB power?
Normal speech will only result in about 1/4 or less average power indication out of a full 12 watts power output.
The peaks are there but the metering cannot follow the power changes as you talk.

 

[Eastside]

How are you measuring SSB power?
Normal speech will only result in about 1/4 or less average power indication out of a full 12 watts power output.
The peaks are there but the metering cannot follow the power changes as you talk.

I have a daiwa cn-801....I just whistle or say audio into the mic.....the needle will not go any higher than 2 watts.....and my other 148 that works properly will swing up to 12 watts.

 

[Robb]

I know that SSB and AM take different paths to the driver/final.
Sure that 'ExitThirteen' (a member here) prolly knows what to look for . . .

 

[Eastside]

I know that SSB and AM take different paths to the driver/final.
Sure that 'ExitThirteen' (a member here) prolly knows what to look for . . .

Yeah..I hope him or somebody who knows these radios chimes in.

 

[Eastside]

Not getting help here.
I guess it gets thrown in the pile of non working radios.

 

[liquidh8]

I have a washington with a 8719 pll I am chasing down a low power issue also. Wish pi could new of some help, but I didn't solve it yet.

I would.make sure you are getting you 12volts to the driver and final at tx if I didn't already do that.

 

[Robb]

Instead of waiting for someone to fix your radio for you from this forum - which is really asking a lot when you consider what is possibly wrong with it - you might instead look at the 'Service Manual' page on this forum. There is a SAMS manual for the 148GTL there. In it, it will give you a chart for each transistor and its voltages. This can help you track the problem area down yourself. May well find the circuit fault this way too.
http://www.worldwidedx.com/cb-radio-service-manuals/141891-cobra-148-gtl.html

Think I would start with the TX mixer circuit. Use the schematic on CB Tricks to find out which parts are in that circuit. Then, check the IC/transistor voltages and the diodes in that circuit.
http://www.cbtricks.com/radios/cobra/148gtl/graphics/cobra_148gtl_sch_redraw.pdf

Either do that, or send your radio to ExitThirteen or another shop and get it fixed and carefully examined . . .