I have the following item for sale. Please respond to me off list if you are interested or need photo documentation:
1 ea. Original OSCAR Mode J Desense Filter . $20.00 $12.00 USPS Priority mail. I will give $10.00 donation to amsat in appreciation for all there help, when I was active on the "Birds".
Uplink on 2 meters downlink on 70cm. This filter reduces the problem of the up link signal desensing the receiver. This filter has low insertion loss(typically less than 0.5dB in the 70 cm band)(This filter and good rejection (typically over 50 dB in the 2 meter band.) This filter should be inserted between the 70cm antenna and 70cm preamp. Transmitting through this filter is not recommended so it should be removed or bypassed before transmitting on 70cm. I fabricated this filter out of 3" copper pipe from a drawing and article in the AMSAT journal a number of years ago. A drawing appears in the 1980 ARRL Handbook. Silver and teflon trim coax fittings used on the input and output connections.
W7TYN AMSAT # 3951