Digital Traffic Network

This week, my amateur radio station became an official digital traffic network (DTN) station. The main operating digital mode is PACTOR, an evolution of both AMTOR and packet radio. PACTOR uses a combination of simple phase shift keying (FSK) modulation, and the ARQ protocol for robust error detection and data throughput. PACTOR is most commonly used on frequencies between 1 MHz and 30 MHz.

I first looked into PACTOR last fall. I abandoned the idea when I learned that the terminal node controllers (TNCs) cost hundreds of dollars, an investment I was not comfortable making at the time. In December, I asked around about becoming a DTN station operator. I was told that the operational mode was PACTOR and I balked about having to obtain the necessary TNC. Then I was told that a used TNC would be provided. All I had to pay was a $15 dollar shipping charge. That was more than acceptable. Soon, the loaner TNC arrived. It was about 25 years old and supposedly could handle the required PACTOR digital node.

Advanced Electronic Applications, Inc. PK-232MBX TNC

I found a appropriate AC/DC adapter, but I had to jury-rig a mic cable to connect it to my radio and the 5 pins on the back of the TNC. I also had a audio cable on hand for the radio output to the TNC. An RS-232/serial port USB adapter cable connects the TNC to my laptop PC.

Breadboard for connecting a CAT6 twisted-pair cable to the TNC

The AirMail software was downloaded and installed on my laptop. That needed to be configured to interface with the TNC. The TNC was switched on and AirMail was opened. Following initialization of the HF mode, the TNC successfully initialized. My radio AGC was set to 6 and for 40 watts output. It was then tuned to a frequency for a nearby PACTOR station. Then the receive threshold was properly set on the TNC. I tried to connect to a PACTOR station but no joy.

After several days of troubleshooting, with the assistance of two fellow amateur radio operators, I tried a loopback test on the TNC. This involved disconnecting the TNC from the radio and connecting the mic and audio input pins, on the TNC, with a jumper wire. Then a terminal software app was setup to connect the TNC with itself. This test failed and indicated the problem was with the TNC.

I was able to obtain an identical TNC on eBay for a modest and very affordable price. When it arrived, I quickly set it up for a loopback test. The test was successful. I then connected it to my laptop and radio, and it successfully connected to a PACTOR station. The operators of two PACTOR stations modified their configurations to recognize my station. Then I was able to send and retrieve national traffic system (NTS) messages.

I now routinely log in to retrieve NTS messages from The 3rd Region Hub for The Western Pennsylvania Section, on every even numbered day, sharing the responsibility with another amateur radio operator who checks in on odd numbered days. After retrieving messages, I relay them via The Western Pennsylvania Phone Traffic Net, or deliver them via phone, email or US Mail. I also originate my own messages to send via the NTS.

Contact me if you wish to originate an NTS message.

More Antenna Woes

Today, one leg of my G5RV antenna snapped off due to the extreme cold and windy conditions. The temperature now is 9 F with a windchill of -8 F. My HF system is now out of commission until I can install a new antenna, or install the new dedicated 80-meter antenna. Sunday it will warm to the low 40s so that is the earliest I can make the attempt. Temperatures will be above freezing from Sunday until at least next Tuesday.


Right now it looks as though my NTS production for January will be a total of 41 handled messages. That is a personal monthly record.


Update: G5RV antenna was replaced.

Antenna Wear and Tear

Stormstown is nestled in Halfmoon Valley. The valley is often windy, with the flow mainly from the southwest. The winds have been taking a toll on my outdoor equipment, mainly the flags and flagpole, and my G5RV HF amateur radio antenna.

Most of the damage has been minor. In the past six months, I have had to replace the dipole wires, resolder the ladder line connectors at the feed point, replace a section of coax due to a broken connection at the feed point, and replace two clamps and three sections for the collapsible mast.

During my latest repair, to replace the coax, I secured the ladder line with cable ties. That may reduce some of the wear and tear on the cables and connections.

I am a frequent check-in on the 3rd Region Net at 2100 UTC (3.918 MHz, LSB), and The Western PA Phone Traffic Net at 2200 UTC (3.983 MHz, LSB). My callsign is WX2DX.

nts_clInformation on the National Traffic System

If you’d like to send a radiogram, send me a comment.

Amateur Radio Traffic Net

Last Week, I became a regular check-in to The Western Pennsylvania Phone Traffic Net. I started to look for a net after the landfall of Hurricane Harvey. The net meets every evening at 6 PM on 80-meters, and is part of The National Traffic System (NTS).

So far, I’ve initiated 4 radiograms. I hope to continue handling NTS messages on a regular basis.