Check the listing for details. HP 34901A / 20 Channel Multiplexer. Condition: Used. Listed at 149.99 USD. The HP 34901A / 20 Channel Multiplexer is a reliable and high-quality data acquisition unit designed by HP. This multiplexer allows for the acquisition of data from up to 20 different channels, making it ideal for complex testing and measurement tasks. With its brand reputation and specific model number, users can trust in the performance and accuracy of this data acquisition system for their analytical needs.