Kantronics KPC-2 - AFSK Output Level Adjustment

AFSK OUTPUT LEVEL
15
AFSK Output Level
Audio Frequency Shift Keying
Jumpers are appropriately labeled on the PC board. Refer to the parts location diagram for help in
locating them. Also refer to the Assembly and Disassembly section for information on obtaining ac-
cess to the interior of the TNC.
KAM – AFSK Output – VHF – Jumper K2
This jumper is provided to alter the VHF AFSK output level. The KAM is shipped from the factory
with the jumper in the LO position. The LO position sets an AFSK output level from the KAM at
10 mV. The HI position sets an AFSK output level of 50 mV. Both levels are peak-to-peak values. In
general, transceivers requiring a pre-amplified microphone will also require the HI level AFSK out-
put from the KAM. Removing the jumper entirely will provide the maximum possible output level of
approximately 1.7 Vpp. Should you require an intermediate value of AFSK modulation signal, it
may be obtained by replacing resistor R12 with the appropriate value chosen from the following
chart. If you change R12 to obtain an intermediate value, place K2 in the HIGH position.
R12 Value
AFSK Output Level
470 Ω
2.2 kΩ
6.8 kΩ
22 kΩ
47 kΩ
24 mV
106 mV
290 mV
680 mV
1000 mV
KAM – AFSK Output – HF – Jumper K5
This jumper is provided to alter the HF AFSK output level. The KAM is shipped from the factory
with the jumper in the LO position. The LO position sets an AFSK output level from the KAM at
100 mV. The HI position sets an AFSK output level of 500 mV. Both levels are peak-to-peak values.
In general, transceivers requiring a pre-amplified microphone will also require the HI level AFSK
output from the KAM. Removing the jumper entirely will provide the maximum possible output
level of approximately 1.6 Vpp. Should you require an intermediate value of AFSK modulation sig-
nal, it may be obtained by replacing resistor R25 with the appropriate value chosen from the fol-
lowing chart. If you change R25 to obtain an intermediate value, place K5 in the HIGH position.
R25 Value
AFSK Output Level
680 Ω
3.3 kΩ
4.7 kΩ
6.8 kΩ
22 kΩ
48 mV
209 mV
282 mV
377 mV
800 mV