You may use the HG-10B external VFO produced by Health
Co.
Connecting The Heathkit HG-10B to the Drake
2-NT Transmitter by
Roy Vickers KF5YU
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.
