Do you have a scope? If so try that first. Even if the BW is lower than 500MHz you should be able to see some signal and it will give you DC levels. That should let you determine if there are SA damaging voltages present. Given the power levels you suggest that should be ok for the SA. HP had some special cable assay¡¯s that would plug into the two ¡°sockets¡± shown. A 10X probe should be OK, AFTER checking for DC voltages and I would ground the probe. ?From the picture I¡¯d suspect that the other pin is a ground connection. Not knowing what the schematic says on that little circuit it¡¯s hard to guess. ?I think it looks like the black diode might be a PIN switch with the ¡°on¡± bias supplied through the glass diode. ?Another question would be where does the fat trace leading to the left of the black diode go? ?It is also DC blocked, so that could mean the PIN diode idea is OK. If that trace goes to an off board connector you could try sampling after the DC blocking cap or if it¡¯s a connector just pull that connector and see what¡¯s there. ?
Hope this helps a bit. ?Just make sure there are no DC voltages anywhere you try to monitor with the SA.?
Steve
