i finally had some time to set up my softrock 80/40 yesterday. i was interfacing it to a dell laptop and a built in audio card it uses. i was only interested in rx functionality.
my softrock had passed all the initial tests. current draw was about 35 ma, the 12 and 5 volt buses were right. i was using rocky 3.4 and fiddling with settings (i am not sure i was actually receiving signals) when suddenly the noise through the laptop became very high and rocky's grass in the display grew alarmingly large. there was a loud, broad, distorted and raucous middle hump and no amount of reconfiguring would diminish it. i then noticed the softrock was drawing 100 ma, and the 2462 dual op amp was warm. i disconnected everything and started trouble shooting. i determined that the 2462 was cooked, showing a near short (7 ohms) between pin 1 and ground. i removed it from the board and the softrock once again was drawing only about 35 ma again. what could have gone wrong? could over driving the softrock input have done it? or possibly some some common ground issue? my antenna was isolated, as was my power supply. the softrock was probably shared a common ground to the laptop. any thoughts? thanks mike - ak3f
