Hi Bob, The tube lineup for the TCS is: V101 - V103 12A6 V104 - V107 1625 V201, V204, V205 12SK7 V202 12SA7 V203, V207 12A6 V206 12SQ7 The rectifier power units use 2 ea. 5R4GY and 2 ea. 6X5GT. Good sailing, David Edsall, W1TDD