Connecting The Heathkit HG-10B to the Drake 2-NT Transmitter
Roy Vickers KF5YU

     Connecting The Heathkit HG-10B to the Drake 2-NT Transmitter

     In order to connect the 2-NT to the HG-10B we need to supply the HG-10B with B+ and 6.3 vac filament voltage. We must also connect the RF Out from the HG10B to the backside of the xtal holder and key the HG-10B from the VFO Key of the 2-NT.

     I accomplished this by building a cable using a 4 pin connector and plug similar to the one used on PC power supplies, in fact if you have an old PC power supply you can use the connector and wires to build the cable. I built my cable using the same color coding of the original Heathkit cable to avoid accidents and confusion. The cable will have a red wire going to +250v, white wire going to 6.3 vac filament, green wire going to the backside of the xtal jack and a black wire going to ground. These wires will correspond to the Octal plug wiring on the HG-10B. I then made another cable to connect the 2-NT/VFO Key to the HG-10B Key jack.

     I then modified the HG-10B by moving the green wire from terminal strip A to the center connection on the RF Out jack. I then plugged my CW key into the front jack of the 2-NT. There is a chart in the HG-10B manual that tells you what value of R11 is needed to drop the B+ voltage down to 108 vdc. My HG-10B already had a 10k/10w resister so I tried that first and it worked even though the manual said I needed a 6k/5w resister. The 2-NT theoretically produces 250 vdc but my meter measured 280 volts so R11 will require some experimentation.

4 Pin Accessory Jack

• 2-NT (xtal block) -> green wire -> HG-10B (RF Out Jack)
• 2-NT (250 vdc) -> red wire -> HG-10B (terminal strip A pin 6 to R11)
• 2-NT (6.3 vac )- > white wire -> HG-10B
• 2-NT (gnd) -> black wire -> HG-10B (gnd)
• 2-NT VFO Key -> HG-10B Key Jack
• 2-NT Key Jack -> CW Key