Cavity (duplexer) Checkup
April 29, 2008 preliminary report) Howard WB4NYT and Bob K2GII took some measurements and made adjustments to the repeater system cavities to attempt improvement. Cavities allow us to use just the one antenna for both transmitter and receiver for duplex operation.
Howard reported changes since adjustment to Sam W4KUM on the repeater. Howard mentioned there is now an additional 4 Watts leaving the cavities headed towards the antenna. That would be a 33% improvement. What was not mentioned was if the additional forward power (4 watts) took care of the reflected power we saw between Transmitter and cavities (4 watts). A dedicated monitoring station could not determine any noticeable improvement. Howard went onto say that desense of the receiver was noted. Howard and Bob attempted to locate a source of desence 'down stairs' but did not detect any. Howard said the desense must be up on the water tower some where. Nothing in the conversation between Howard and Sam was mentioned about the cavities for the receiver side. A dedicated monitoring station is still determining what if anything has changed for both transmit and receive. Given the current mysteries, namely crackle and reception changes that tend to be related, the observation will go on for a while. Any more news on this subject will be added here.