User's Manual
15
Upon reaching 700W forward power check the following parameters (continuous carrier operation):
-
the reected power must not exceed
~78W (for SWR 2:1) or better still to be below 28W (for
SWR 1.5:1);
-
PA DC CURRENT must be between 25 and 30A; it is normal that the current varies within these
limits when changing operating frequency and antenna impedance;
-
PA DC VOLTAGE must be within 48 – 52V;
-
the transceiver’s SWR reading must be below 1.2:1.
Enter the MEASURE menu and check:
-
the drive power from the transceiver must be between 23 and 40W;
-
PA BIAS, which must be between 1.8 and 2.0V (typically 1.9V);
-
PA TEMPERATURE, which must be between the ambient and 80ºC (176ºF), depending on the
power
level and the duration of transmission.
f)
Elimination of electromagnetic compatibility (EMC) problems.
If you use an amplier for the rst time in your shack, you may need to make some improvements in the
setup. It is possible you might experience tingling from metallic objects due to the stronger radiated RF
eld. It could affect the operation of your station or systems outside, if they are too sensitive – typical
examples are the microphone, CW keyer, computer keyboard / mouse, as well as TV receivers, Hi-Fi,
intercom or telephone setups and others.
For instance, induction of RF currents into the microphone, CW keyer or computer keyboard, may lead
to distortion
in the peaks or self-oscillation in SSB mode, “sticking” or breaking off the dots or dashes
from
a
Morse
keyer,
or
garbling
computer
screen
images.
For
the
elimination
of
such
problems
we
recommend that you take the following general measures:
-
minimize
the
radiation
from
the
feed
lines
by
reducing
the
common
mode
currents
in
them,
improve the balance of antennas and feedlines;
-
in case you use
asymmetric
antennas (GP and similar) install as many radials as practical (use
a well-developed counterpoise system);
-
add current chokes on the coaxial feeders;
-
place
as
far
away
as
possible
(also
by
height)
the
radiating
elements
of
antennas
from
the
premises, where the affected devices are located; in this sense, asymmetrical antennas without
a separate feeder (Long Wire, Windom, and similar) may cause more interference because their
radiating element begins immediately from the shack (part of it is the feeder itself);
-
if the use of asymmetrical directly fed “wire” antennas is inevitable, use mainly half wave or half
wave multiple – they have a high input impedance, operate respectively with a small current
in the feed point, and in the grounding of the shack; thus you can reduce the strength of the
disturbing RF elds more than 10 times (at the same radiated power) compared to the case
with quarter-wave and multiple to quarter-wave antennas of this class – you should avoid them
because they have a low input impedance and operate with a large RF current in the grounding
system
and
in
the
power
supply
network
respectively,
i.e.
they
create
stronger
disturbances
(RFI);