Up until three days ago, the two combinations possible from Garmin (the leader in the industry) was the "old" Astro 220 handheld receiver (discontinued) was compatible with the DC30 and DC40 transmitting collars. The newest version transmitting collar - the DC-50 is not compatible with the Astro 220.
Below depicts the compatibility between units, and the availability of being able to purchase a unit that would work.
I struggled with why would a company that has a great selling, approved for use collar suddenly discontinue it without an approved replacement unit? People still have functioning 220's and the DC40 is compatible with it. Not everyone has the disposable income to buy a new 320/50 combo! But, it seems that is the goal of Garmin. Forced retirement of perfectly good, accepted for use gear.
By reviewing the graphic below, it's illustrated they want the market to move fully to the 320/50 either when the DC40 collar gives out or the 220, forcing a major purchase or finding a different solution.
It would appear that there is only one option left if you need a new piece to the system. You can't upgrade in any other way than to have the 320/50 combination. Problem is - if you have to and compete, you currently have a problem. That combo is not approved for use in performance events!
I can't think that they had no idea the collar was not approved for use - they must be smarter than that, right? Maybe not, maybe so - we will probably never know.
I understand the constant need to improve and have a new product line coming out. But this early termination of not very old technology that people have invested substantial sums of money already to use doesn't evoke a feeling of partnership between Garmin and it's customers. Especially seemingly uncaring that the very staunch supporters of the system cannot use the new version in competition - on this note Garmin has tossed the proverbial baby out with the still hot bathwater. It's like building a car and then two years later ensuring there is zero parts available to keep the car maintained and on the road. Do that more than a couple times and folks might just look for a different brand of car.
I've been impressed with Garmin in the past, and know this is a small part of their overall portfolio, but the company has dropped more than a couple points in my eyes on this one. They need to consider themselves partners with their customers and take a long term approach vs. just focus on increasing sales by discontinuing parts of a good expensive system that has several years of valued service still available.