Jim, Getting directly back to your original question, I built a KD9SV preamp, and it has clamp diodes included in the design (I did not add them, they were part of the original design by KD9SV). Does you KD9SV preamp already have clamp diodes protecting its input, and if so you have already answered your own question about adding clamp diodes to protect it (no reason to add them if you already have them).
If you go one step more and follow the advice that others have provided here, you might consider removing the clamp diodes (if you have them) based on their comments, but please understand that the gain of you RX antenna is approximately -36.3 dbi (based on the dimensions you told me), and it's very possible that you will not encounter the same kind of problems (using clamp diodes) as those using beverage RX antennas on 160 meters just due to the greatly reduced signal strength that your RX antenna provides compared with a full size beverage. That's all I'm saying on this topic, over and out. Don (wd8dsb) _________________ Topband Reflector Archives - http://www.contesting.com/_topband