The Yaesu 1023 would be more than sufficient for a FT-2900.
Look for 13.8V nominal output and match the supply's capacity to what the radio draws maximum.
For example, for the FT-2900.
Supply Voltage: DC 13.8V ±10%, Negative Ground
Current Consumption (typical):
RX: Less than 0.7A (max. audio)
Less than 0.3A (Squelched)
TX: 15A (75W) / 9A (30W) / 5A (10W) / 4A (5W)
So you need a maximum of 15A.
"The Yaesu FP-1023 power supply provides 13.8 VDC at 23 amps. Input is 120 VAC 60 Hz."
So PS capacity > radio max, you are good to go. However, while this is a nice supply, it's more than you need (and need to spend, about $175). If you don't see yourself adding a 100W HF and/or VHF rig, then you might consider something like the Astron RS-20. This is about $100 typically and a very solid supply. Does 16A sustained, 20A transient.
BTW, I don't think Radio Shack sells anything useful like this anymore. Also consider eBay or Craigslist. And old Heathkit or really any old linear power supply could be a nice option because they are so very simple that if they don't work we can rebuild or fix it.
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