3. Installation
38
modulator to generate the HF signal. This is of no disadvantage, providing the
transceiver is not overdriven.
Some useful hints to properly setup the transceiver:
x
If possible use a 500 Hz IF-filter for PACTOR-II. Never use a IF-filter with a smaller
bandwidth than 500 Hz! IF filters (SSB-filters) with wider bandwidths won´t cause
problems at all. Although the filtering by the DSP of the PTC is always optimal, it is
desirable to prevent noise from the input of the PTC as far as possible.
x
For PACTOR-III use a 2.4 kHz wide filter (usually also used for SSB/voice). Do
not
use a
smaller one.
x
Do not use any audio processors. The speech-compressor of the transmitter will damage the
PACTOR-II/III signal in the same way as external DSP-audio-filters will do. These
external DSP-audio-filters create unpredictable signal propagation delays which are not
acceptable. The PTC filters the signal perfectly with the integrated DSP and requires no
“external help”.
x
Noise blanker and notch filter should be switched off.
The PTC is connected to the transceiver via an 8 pin DIN socket (HF-Transceiver Audio).
PIN 1:
Audio output from the PTC to the transmitter.
The PTC supplies a pure audio signal
to the microphone (or ACC) input of the transceiver. The output amplitude can be
adjusted with the
FSKA
and
PSKA
commands from 30 to 3000 mV (peak to peak) open
circuit. The output impedance of the PTC is 1 k
:
.
PIN 2:
Ground (GND).
Collective ground for all signals.
PIN 3:
PTT output.
While transmission this output is grounded by the PTC, so that virtually
all modern transceivers are usable. A VMOS power transistor is used as switch, which
gives optimum results.
PIN 4:
Audio from the receiver to the PTC.
The PTC receives the incoming signal directly
from the loudspeaker output of the receiver. The volume should not be turned up too
much. A
fairly low
volume is quite sufficient. It is better to take the AF signal from a
low level output which is independent of the volume control. These outputs are often
labeled AUX or ACC. The input impedance of the PTC is 47 kOhm. The PTC operates
with an input signal down to approx. 10 mV
p-p
and should not be driven with more than
2 V
p-p
.
PIN 5:
Optional power supply input.
The PTC can be supplied with power via this input.
This is especially useful if the transceiver gives a power supply output via the AUX
socket. The PTC requires approximately 10 to 20 V at a maximum of 500 mA, typically
200 mA.
PIN 7:
Not connected.
PIN 6:
Not connected.
PIN 8:
Not connected.
For immediate connection of the PTC to the transceiver use one of the cables you find in the
accessories catalog chapter 5 page 49.
