I think there are TWO incompatible applications being discussed:
1) The original request was for narrowband BPF for portable operating on a mountain top in the presence of commercial transmitters. Usually needs a relatively large cavity or heloical resonator. This is for the annual APpalachian Trail GOlden Packet event 17 July http://aprs.org/at-golden-packet.html
2) The more common AMSAT need for a LPF to prevent front end overload of the third harmonic of a VHF upllink into the UHF receiver.
The solutions are very different. - Bob, WB4APR
On Thu, Jun 10, 2021 at 2:08 PM Joseph B. Fitzgerald < jfitzgerald@alum.wpi.edu> wrote:
Mini-circuits has sub $100 filters available suitable for receiving applications:
https://www.minicircuits.com/WebStore/RF-Filters.html
Meeting the 0.5 dB insertion loss specification might be difficult though.
-Joe KM1P
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org