Peter, DF8BB Hi, since March last year my K2/100/KAT100 was working very good, but in last December I was tuning an antenna when suddenly it shut down and I could not repower it again. (I guess I was selecting the wrong antenna) After that, one of the PA transistors was damaged and I replaced it. Now it seems to be ok but in low power the - HI CURR - warning appears and the the SSb transmision was very distorted.
So I knew i have to do some troubleshooting. I removed the KPA 100, SSB board, KAF board and the 160m board. I placed the required jumpers across J9, J10 and C167 across pin 7/12 of J11, jumper W1 left open. I did some testing but at least the warning - HI CURR - is appearing immediately when transmitting, regardless to the setting of the power controll. I checked the transmitter and the TR-switch and replaced the entire transistors, diodes and inductors in these stages. All resitors and capacitors have been checked and they are ok. 8T and 8R switching is working. (there is only 7.6 Volt due to the voltage regulator) I rewound T2, T3 and T4. I lifted up the output winding and supplied RF to the LPF input and there was no RF at any LPF except the selected Band. I replaced D9 and checked the resistors at the RF detector circuit. At this time the PA transistors Q7/Q8 are not installed, because I think there is something wrong on the control board starting at VRFDET to U6, U8, U10A, and the ALC circiut. Before I go and kill some more PA transistors I would like to know if somebody has any suggestions how to check the contorl board VRFDET, VALC and ALC without installed Q7/Q8. My Idea is to apply DC voltage at VRFDET to see how the ALC and the Power control are working. But I`m afraid of some more damage doing that, has anybody experiences with that? thanks for any help... 73 Peter, DF8BB
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