Hi, I now need one more 1.8 KHz filter for my K3s Sub Rx. I have one 1 KHz Elecraft/Inrad that is surplus to my needs. If you have a 1.8 Elecraft/Inrad for sale or want to trade for my 1 KHz filter, or if you would like to buy my 1 KHz filter, please contact me off list. Thanks & 73, Gary KA1J