The new amp seems to meet the same basic need as the neat old TenTec 405 amplifier that mates so well with the 509 and other QRP rigs as well. 72 de Chas W3KC Jim Miller K4SQR posted: >I am certain the new 100 amp has been developed due to hundreds, if not > thousands of requests, > from Argonaut 509 and later QRP models needing a little more oomph at > times.