This was part of my Smaart measurement system.  I have a second identical setup, just no longer need 4 channels of RF.  

This MiPro ACT828 Wireless System includes:

• (1) ACT828 2ch receiver with (2) 1/2 wave antennae and front mount antenna kit
• (2) TA80 plug-on transmitter
• (2) ACT-80TC belt pack transmitter
• (2) headset mics
• (1) MP-80 battery charger with AC adapter
• (2) IEC power cables
• (4) rechargeable batteries 
• (2) battery cases
• (2) zippered transmitter cases

The TA-80 plug-on transmitter can provide selectable 12 or 48v phantom power and up to 48dB of gain in 6dB steps. With 48v phantom power and RF power set to 50mW, you can expect about 4.5 hours of life per battery charge with a low sensitivity microphone. The TA-80 transmitter uses a rechargeable ICR 18500 lithium ion battery.