Transmit/Receive Relay For Dentron GLA-1000B After Conversion To Svetlana EL-509/6KG6 Tubes
Relay is a Midtex part number# 157-13B-200 (12VDC, 10 AMP Contacts, Open frame, 3PDT)
Resistor between #1 and #4 is a 75K OHM 1 Watt and is there to drop the cathode bias. This cuts the tubes off in stand-by or receive conditions in order to increase the life of the tubes (keeps them cooler when not is use!!!)
***Contact #3 and #5 are connected with a jumper***
Summary:
IN
THE STAND-BY MODE OR IN RECEIVE ZENER CATHODE
BIAS IS DROPPED ACROSS THE
75K OHM
IN
RECEIVE
MODE
SIGNALS COME IN FROM ANTENNA VIA
CONTACT #3 TO
OUTPUT SELECTOR SWITCH
IN
TRANSMIT THE RF
DRIVE GOES
INTO CONTACT
#9 (HF IN) TO CONTACT #6
(INPUT TO THE FINALS AT
***Don't
forget to install a 1N4007 diode across the relay's coil connections** The
cathode (band) of the diode is soldered to point (y), =DC, on the schematic**
and the anode of the diode is soldered to the -DC side.