I am designing the payload for a high altitude balloon, and was looking at the HX1 - VHF Narrow Band FM APRS Transmitter (144.39Mhz - NA) to use as a transmitter for the US, but the product is retired. What is recommended to use in replacement? Please let me know. Thank you.
Link below is the manufacturer, they should be able to help get you in touch with a distributor.
https://www.radiometrix.com/contact/
Note that these modules REQUIRE at least a technician class ham radio license to operate.
Thank you for directing me to their contact. I will message them.