Got a friend that's having an issue with very low modulation output on AM, but very loud on both SSB and PA modes.
SSB is around 20w peak, which sounds about right. And the modulation is loud.
PA mode modulation is very loud also.
But AM Modulation is very low, only bout 8w peak.
1. He swapped out the 1419 passthrough with an NTE-152.
2. Replaced all electrolytic caps in the audio chain with same UF values but increased voltage ratings to 25v.
3. Cleaned the mode control and modulation control, along with the AM Modulation adjustment inside.
4. R153 is 10 ohm, not 12 ohm.
5. R104 was clipped and still low AM Modulation. Replaced it after testing.
6. Checked voltages on the TA7222AP Audio IC.
Any suggestions I could pass his way? He's learning, and listens very well to instructions.
SSB is around 20w peak, which sounds about right. And the modulation is loud.
PA mode modulation is very loud also.
But AM Modulation is very low, only bout 8w peak.
1. He swapped out the 1419 passthrough with an NTE-152.
2. Replaced all electrolytic caps in the audio chain with same UF values but increased voltage ratings to 25v.
3. Cleaned the mode control and modulation control, along with the AM Modulation adjustment inside.
4. R153 is 10 ohm, not 12 ohm.
5. R104 was clipped and still low AM Modulation. Replaced it after testing.
6. Checked voltages on the TA7222AP Audio IC.
Any suggestions I could pass his way? He's learning, and listens very well to instructions.