On 6/24/22 09:12, BeetleJerald Oliver wrote:
I am still having desense on my UHF downlink on the IC-9700. Antenna is a 30 element M2 CP Yagi with SSB Preamp at the antenna.
Your de-sense problem is compounded by the gain of the SSB pre-amp (LNA). A suitable filter inserted between the antenna and LNA would probably fix the issue.
N0GVK's suggestion of http://www.parelectronics.com/sat-amateur.php is an example of something that would work. A simple diplexer, such as the Comet, would also work.
The problem with adding it in the shack, as N8MH suggests, is that you've already amplified the problem by the gain of the LNA. Indeed, your LNA may be overloaded by your 2m transmit signal and the filter in front of it will eliminate that.
TANSTAAFL: Insertion loss will increase. However, we're not EME, so a few tenths of NF increase shouldn't matter.
--- Zach N0ZGO