16 Nov
2023
16 Nov
'23
3:20 p.m.
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