Bongo Bass and wireless

I’ve used two types of wireless systems with my Bongo, a Donner DWS3 and Joyo. I’ve used 2 Donners, and they are now “cutting out” frequently enough to be unusable. The Joyos have worked fine when playing, but there is a very loud hiss. I also have a Sterling Ray 35. The Joyos also hiss with that bass. (Neither of the basses hiss with the Donners).

None of the wireless units hiss with my Majesty or my St. Vincent. (The Donners cut out.)

I’ve heard that a short cable to connect the wireless to the bass (and put the wireless in a pocket) might help. I have one on order.

Here is my question: Could the Bongo itself be the cause of the failure? I have a third Donner which I don’t think has ever been plugged into the bass, and it works flawlessly. I’ve marked it and will not ever use it with the Bongo.

Second question, are there better solutions? It looks like there are more expensive units that have receivers that require power. I’d rather not do that. The cost is really not prohibitive, but I want fewer cords, not more.