Heathkit SB-401 Assembly Manual page 164

Relative power readings are obtained by recti-
fying a small amount of the RF output with
diode D9. This rectified (DC) voltage is applied
across the meter, and is adjusted by relative
power adjust control R36 for full-scale deflec-
tion on the 3.5 megahertz band.
Since the voltage source is the center tap of the
high voltage doubler circuit, the meter indi-
cates 1000 volts, full scale, or the voltage
that should be present at the high voltage tap of
the voltage doubler.
Relative Power (Figure 6-20)
Figure 6-20
With the meter connected in parallel with re-
sistor R42 and in series with R43, and with
500 volts from the power supply impressed
across this resistor combination, there will be
1 milliampere
of
current through the meter.
A
current of 1 milliampere through the meter
will cause full-scale deflection. Resistor R42
limits the voltage on the Meter switch when it
is not in the HV posttion,
RELATIVE POWER
High Voltage (Figure 6-19)
-
- -
R36 C80
600
REL. PWR. .005
ADJ.
Figure 6-19
-
loon
IMA
F'S
VEL
R35
1000
H rGH VOLTAGE
-
-
500K
R34
10K
100.n.
IMA
F'S
1142
10K
fiNAL
TANK
1143
ANTENNA
@--~~--
HV
DOUBLER
CENTER
TAP
Page 138