Two Meter Packet Station

Two Meter Packet Station
Bernie Huth, W4BGH 1/26/11 Two Meter Packet Station Recommendation for Portable Operation. Simplicity and the therefore a reduced probability that an inexperienced packet operator will have difficulty assembling a portable station takes priority over the lowest cost in this recommendation. • A premium is placed on selecting a transceiver which has TX/RX audio and PTT available on a dedicated “digital” connector because this provides the simplicity and reliability desired for field operation. The alternative is a separate plug from an “External Speaker” jack (RX audio) and a connection to the transceiver microphone jack (TX audio and PTT). RX audio derived from the “External Speaker” jack is usually controlled by the radio’s volume control which is one more factor that can cause problems in the field. • A TNC costs more than a sound card solution, but it is the simplest to connect and operate correctly and therefore the most reliable interface between the radio and the transceiver. The use of a sound card also requires the use of third party software1 that also increases the difficulty of setting up a packet station. • Many newer generation laptop computers do not have RS-­‐232 ports, so a USB-­‐to-­‐
RS232 adapter is included. The RS-­‐232 port will be needed for many TNCs and to provide PTT for a sound card configuration. Version 1 New Price E-­‐Bay Estimate Alinco DR-­‐135TMkIII 2-­‐Meter Transceiver $179.95 $135.00 Kantronics KPC3+ TNC2 $199.95 $140.00 Samlex SEC-­‐1223 Power Supply $99.95 $70.00 Keyspan USA-­‐19HS USB Serial Adapter $45.99 $26.90 Total $525.84 $371.90 Version 2 Kenwood TM-­‐271A 2-­‐Meter Transceiver $174.95 $149.00 Kantronics KPC3+ TNC $199.95 $140.00 Samlex SEC-­‐1223 Power Supply $99.95 $70.00 Keyspan USA-­‐19HS USB Serial Adapter $45.99 $26.90 Total $520.84 $385.90 1 The third party software is AGWPE or AGW Packet Engine Pro. 2 The KPC3 TNC can be substituted (an older version) which may be preferable since the audio level to the transceiver is controlled by a potentiometer instead of a software command. This hardware audio level control is less likely to be accidentally changed by an operator in an emergency situation. A KPC3 can be found on E-­‐Bay for slightly over $100. 1 Bernie Huth, W4BGH 1/26/11 The American version of the Kenwood TM-­‐271 does not have a digital connector, but it is easily modified to create one. The photograph below shows 6 solder pads on the PCB which make the necessary signals available. The wires from a cable can be soldered to the pads and the cable can be routed outside the enclosure under the power lines indicated by the arrow. If a female DB9 connector is wired to the cable according to the Figure below it will be compatible with the Alinco DR-­‐135. Note: R119 removed to "open" the radio.
PKD
PKS
9
5
GND
GND
RXA
TXA
PR9
Both 1200 and 9600 baud signals
not affected by squelch.
PTT
6
1
SQC
SQC
CN2 connections inside
TM-271A
Female DB9 connected
to TM-271A wired like
Alinco DR-135
Packet Modifications to Kenwood TM-271A
2 
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