designed to tune from 50 to 70Mhz to
cover both 4m and 6m. Using a
single Gi-7B it should give 400W
(continuous) for 15-20W drive.
showing the SWR meter and the
controls. A grid tune control
will be fitted in the bottom
The single 12v 150mA fan should be
enough to cool the valve under
(CW/SSB) operating conditions.
showing grid fan inlet (12v Mini
from PC CPU coolr), BNC for drive
input and the locking DIN
heaters and HV (-ve). The floating
coax on the right has a HV BNC
for linking to the PSU. A PL259
plug will be fitted on the rear
for RF out
showing mounting arrangements.
The anode connection is made from a
thin brass strip and the grid ring
turned from brass (G4VVT).
choke (on PTFE stock) is mounted
directly onto a 680pF 10kV doorknob
using a small turned brass ferule.
compartment. The small CPU fan
directly onto the heater/cathode
connections which are again made
thin brass strip.
wire for the coils is from 30A
cable. the heater choke is
wound on ferrite rod (from a scrap
A close-up of
the SWR bridge from a design in the