I would expect 100W PEP on AM. That’s not unusual. For this radios issue, I would test: 1. The DC voltage going into the PA board with full modulation on sideband. Use an audio generator to modulate it consistently. Likely this is ok since the AM is going to 100W. 2. Disable the “FOR” forward power metering. Usually you just lift and ground the signal. It will be from the filter board most likely. This will tell you if the radio is erroneously limiting the power based on this reading. 3. Measure the drive signal going to the PA using a high impedance probe while it is connected from main board to PA. Calculate the wattage of drive. 4. Repeat measurement 3, but pull the drive cable out from the PA board and terminate to 50 ohms. Any difference can indicate something of interest. 5. Just a thought, you may have an export version that is for lower power. Check the rear for the exact model number. I saw the export-style DC common-mode filter in the back. This filter, j believe, is not on the domestic models. At least that is the case with most other Icom radios.
@@timtimeprojects3576 also, the PA board will have a low value resistor like 0.1 ohm or so in series with the voltage going in. The PA current is monitored with a differential reading across the resistor. You can temporarily disable this measurement by shorting across the resistor. This can help if the circuit limit is set wrong.
I would expect 100W PEP on AM. That’s not unusual.
For this radios issue, I would test:
1. The DC voltage going into the PA board with full modulation on sideband. Use an audio generator to modulate it consistently. Likely this is ok since the AM is going to 100W.
2. Disable the “FOR” forward power metering. Usually you just lift and ground the signal. It will be from the filter board most likely. This will tell you if the radio is erroneously limiting the power based on this reading.
3. Measure the drive signal going to the PA using a high impedance probe while it is connected from main board to PA. Calculate the wattage of drive.
4. Repeat measurement 3, but pull the drive cable out from the PA board and terminate to 50 ohms. Any difference can indicate something of interest.
5. Just a thought, you may have an export version that is for lower power. Check the rear for the exact model number. I saw the export-style DC common-mode filter in the back. This filter, j believe, is not on the domestic models. At least that is the case with most other Icom radios.
That just kind of surprised me a bit.
@@timtimeprojects3576 also, the PA board will have a low value resistor like 0.1 ohm or so in series with the voltage going in. The PA current is monitored with a differential reading across the resistor. You can temporarily disable this measurement by shorting across the resistor. This can help if the circuit limit is set wrong.