The Blackmagic HDMI to SDI micro converter is fantastic, super stable, and $50 USD. Easily purchasable at any major camera retailer - B&H, Adorama, even Amazon. It’s powered off of a micro USB, which is easy to get an adapter from a P-Tap/D-Tap for, and power it off of your sled. I think it’s a little notch above a lot of the cheaper converters you can get off of Amazon and eBay, as I’ve had mixed results with those.