Integration of External Band Pass Filters

Bud Trench

I am experiencing an issue with band pass filters (BPF) here that I don’t understand and I am hoping that someone can help me work through it.


I have been experimenting with BPFs to eliminate interference while doing single operator two radio contesting (SO2R).


My K3 includes the KRX3 sub receiver, KAT3 ATU and KXV3 option.  The BPFs are 100W units manufactured by LPS.


My experiment tested two configurations as follows:


1.  BPFs connected in series with the coax going to the rear panel Antenna 1 connector.

2.  BPFs connected between the rear panel connectors RX ANT IN and RX ANT OUT.  The RX antenna was activated from the front panel.


I transmitted a 500 CW signal on 10M and the K3 was receiving on 10M.


Configuration 1 worked fine with no interference heard on 10M.   Configuration 2 did not work – strong interference was present and I got a “High Signal” warning.  I would have expected similar performance in both configurations. 


I really would like to use Configuration 2 as a permanent solution but it appears not to work.  Any advice?




Bud AA3B

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