Palstar AT4K Owner's Manual - page 5
16
Operating Your AT4K
1-800-773- 7931 W W W .PALST AR.CO M
Troubleshooting
If you hear a spitting sound while
tuning your AT4K at high power,
you are probably tuning into an imp-
edance that is on the low side (20Ω –
40Ω).
In this event, either reduce transmit-
ter/amplifier power to a lower setting,
or change to a higher antenna im-
pedance by using a different antenna or
modifying the existing antenna.
As seen in the chart to the right, an
antenna capacitance setting that is too
low under these conditions will result
in excessivly high voltages, high losses,
and poor efficiency.
In the first instance the tuner will arc
and suffer almost 16% loss, of which
80% will be dissipated in the roller
inductor.
1500 Watts into a 25
Ω
load @3.5Mhz
8 Ω − 15 Ω
500 watts (all bands)
15Ω − 25Ω
1000 watts (all bands)
25Ω − 50Ω
1500 watts (all bands)
50Ω − 2000Ω
160M — 2000 watts
80M - 15M — 2500 watts
10M — 1000 watts (29.5 MHz
max)
Power Specifications
(assuming single tone key down)
Antenna Impedance
Max Power Rating
IF IN ANY DOUBT ABOUT YOUR ANTENNA
IMPEDANCE PLEASE MEASURE IT WITH A
PALSTAR ZM30 ANTENNA ANALYZER BEFORE
ATTEMPTING HIGH POWER OPERATION.
Ant Cap Inductor Voltage
Loss
100 pF 11.7 µH
4550
16%
200 pF
6 µH
2400
8%
300 pF
4 µH
1600
6%
General Description 5
1-800-773- 7931 W W W .PALST AR.CO M
The Palstar AT4K Antenna
Tuner is an American made im-
pedance matching network that
can provide unbalanced or bal-
anced output.
The AT4K T-matching network
utilizes a 1:1 unbalanced-to-
balanced transformer in the in-
put of the network. When the
network is properly tuned, a 50
Ohm impedance will be pre-
sented to both the input and
output of the balun allowing it to
operate at maximum efficiency.
The AT4K optimizes the per-
formance of your antenna and
transmitter by providing adjust-
able impedance matching using
a T type circuit configuration.
The AT4K also measures the
power and Voltage Standing
Wave Ratio (VSWR) which al-
lows you to tune the SWR to the
lowest ratio for the selected
transmit frequency.
Integrated into the AT4K is a
frequency compensated, lighted
dial, dual-movement SWR me-
ter. The meter features the abil-
ity to read True Active Peak and
Peak Hold.
Designed to handle both Bal-
anced line feeds and coax
feeds, the AT4K features a
front panel mounted switch to
select between feeds.
Tuning is achieved with the front
panel mounted controls. The
dual Vernier dials allow for tun-
ing with precision and accuracy,
while the Inductor crank handle
facilitates coarse adjustments.