HackRF supports frequencies from 1MHz-6GHz but is only capable of transmitting and receiving at half-duplex, which is a major limitation I'm running into. Planning some digital repeater experiments on 70cm band and need simultaneous TX/RX capability. The HackRF One was developed by Michael Ossmann and attracts interest from amateur radio enthusiasts and RF security practitioners. For those who've worked around the half-duplex issue - are you using multiple HackRF units, or would something like a BladeRF be a better investment? Budget is around $800-1000 for the SDR platform.

BladeRF is full-duplex making it ideal for high performance applications like your repeater work. If budget allows, the BladeRF 2.0 micro would be perfect for simultaneous TX/RX on 70cm. Much better than trying to sync multiple HackRF units.

I've used dual HackRF setups for similar projects - it's doable but requires careful timing coordination in GNU Radio. The BladeRF route is cleaner but more expensive. Have you considered the ADALM-Pluto? ADALM-Pluto is designed as a portable RF lab for students and self-learners and supports full-duplex operation.

What specific digital mode are you planning for the repeater? Some modes like DMR have tighter timing requirements that make the HackRF half-duplex limitation even more challenging to work around.