On 11/16/23 09:06, Herb Sims via AMSAT-BB wrote:

I already have that in system.  My 2m LNA is getting overloaded due to frequencies below the 2m pass band (since the diplexer is LP/HP combo….

If you don't have money, you can substitute time/effort to build one.

As mentioned before:

https://reflector.sota.org.uk/t/helical-filter-for-2m/5820

Transmit into it (5W) with a dummy load connected to the other end and a SWR meter on the transmit rig side. Adjust screws for minimum SWR over band of interest.

To really adjust it right, find a nearby ham with a nanoVNA. However, you'll probably be fine with the guerilla method of tuning.

--- Zach N0ZGO