Also looking for info on the D-4065. I have one of each and I'm wondering about what power it can handle, frequency, and proper tuning (beside just taking off the little caps on the tuning screws and getting out the golden screwdriver).
Images of the two units:
I have found out so far that the low pass filter in question usually was on the output of an Isolator such as the 7R011 from the same company. I found this isolator and the two low pass filters together so I'm guessing they had been used together:
Any additional info would be greatly appreciated!
JJ Smith
K5RPD