14
Operating Your AT5K cont’d
4. Any time a new or different antenna is connected, it is necessary to repeat
the tuning procedure for the new antenna.
Troubleshooting
You hear a spitting sound while tuning your AT5K at high power.
You are probably tuning into an impedance that is on the low side (20
Ω
– 40
Ω
).
In this event, either reduce transmitter/amplifier power to a lower setting or
change to a higher antenna impedance by using a different antenna or modifying
the existing antenna.
Also, try to find the highest capacitance setting (i.e. closer to 100 on the dial) on
the output knob. This will probably require re-adjustment of the inductance
setting.
An antenna capacitance setting that is too low under these conditions will result
in excessivly high voltages, high losses, and poor efficiency.
For example: at 1500 Watts into a 25
Ω
load @ 3.5Mhz will produce the
following:
In the first instance the tuner will arc and suffer almost 16% loss of which 80%
will be dissipated in the roller inductor.
8
Ω − 15 Ω
Ω − 15 Ω
Ω − 15 Ω
Ω − 15 Ω
1000 watts (all bands)
15
Ω − 25 Ω
Ω − 25 Ω
Ω − 25 Ω
Ω − 25 Ω
1500 watts (all bands)
25
Ω − 50 Ω
Ω − 50 Ω
Ω − 50 Ω
Ω − 50 Ω
3500 watts (all bands)
50
Ω − 2000 Ω
Ω − 2000 Ω
Ω − 2000 Ω
Ω − 2000 Ω
160M — 3500 watts
80M - 15M—3500 watts
10M — 1500 watts (29.5 MHz max)
Power Specifications
(assuming single tone key down)
Antenna Impedance
Max Power Rating
Output Cap
Inductor
Voltage
Loss
100pF
11.7 µH
4550
16%
200pF
6 µH
2400
8%
300pF
4 µH
1600
6%
Rear Panel Description 7
1-800-773-7931 WWW.PALSTAR.COM
12 VDC INPUT (2.1
mm plug) for 12VDC
@ 500mA to power
the metering, lamp,
relay and fan.
RF INPUT coaxial
connector for input
from transmitter or
amplifier.
GROUND post/wing nut
ground connector.
BALANCED OUTPUT two
nylon High Voltage post
connectors for output to RF
balanced twin-lead antennas.
Relay switched from front
panel control.
COAX 2 coaxial connector
for output to Antenna Two.
COAX 1 coaxial connector
for output to Antenna One.
BYPASS coaxial connector for
output to dummy load or reso-
nant antenna. Bypasses tuner,
but meter circuits are on if
12VDC adaptor is connected
to jack located on rear panel.
FIGURE 1 REAR PANEL CONNECTORS
