Ion Petroianu, VA3NOI
You can sure try. Depending on the DC/DC converter you have it might work.
In my case the model I had on hand (for which I've posted the link in my previous post) generates a lot of switching noise on the 12V power line. That increases the receiver noise which is quite high from the start.
For the PA the current requirements are only 1.5A to 2 A. If it is for desk use I would use a second linear power supply for PA. If you have a 120V to 24V transformer that can deliver 2A I would make a power supply just for that.
A good option is this:
Second option has higher output current capability but you cannot adjust the current limit and the voltage is set using a multi turn trim pot.
You need to find a good heat sink for the power transistor.