Hey guys,
This is the same 148 I was dealing with in the other thread but I decided to focus that thread specifically on the frequency mod. I've had this 148 for a while now and despite having aligned it and it being an overall good performer the one issue I never took care of was the low volume on receive and the low modulation on transmit. SSB modulation seems fine but when I compare the AM from this radio and another 148, my locals say the other one sounds much better. The receive volume is about half of what the other 148 is even when it's turned all the way up. This is not a receiver issue as it has been aligned and is quite sensitive. The problem seems to be in the actual audio stages.
My question is, does the radio use the same audio IC for modulating AM as it does for amplifying the receive audio? So far my best guess is that it could be a bad coupling cap somewhere along the audio chain of this audio IC. Anything else I should look for? Is the output transformer also shared for modulation and the speaker output?
This is the same 148 I was dealing with in the other thread but I decided to focus that thread specifically on the frequency mod. I've had this 148 for a while now and despite having aligned it and it being an overall good performer the one issue I never took care of was the low volume on receive and the low modulation on transmit. SSB modulation seems fine but when I compare the AM from this radio and another 148, my locals say the other one sounds much better. The receive volume is about half of what the other 148 is even when it's turned all the way up. This is not a receiver issue as it has been aligned and is quite sensitive. The problem seems to be in the actual audio stages.
My question is, does the radio use the same audio IC for modulating AM as it does for amplifying the receive audio? So far my best guess is that it could be a bad coupling cap somewhere along the audio chain of this audio IC. Anything else I should look for? Is the output transformer also shared for modulation and the speaker output?