Interoperability of FoxTrak tracker and Argent Data’s OT3 – Part 2

Further tests have been conducted and observations made of normal on-air traffic.

The question that arises is why everything else I have tried except
OT-USB and OT3 devices reliably decodes the Foxtrak (DK7IN, aprstracker 0.11, TT1), and the OT-USB and OT3 devices reliably
decode everthing else I have tried (including TT3+) except the Foxtrak (DK7IN, aprstracker 0.11, TT1). Continue reading Interoperability of FoxTrak tracker and Argent Data’s OT3 – Part 2

Earth continuity testing of amateur equipment

Electrical safety testing of equipment is covered by AS/NZS 3760:2010 In-service safety inspection and testing of electrical equipment.

This article describes how to test earthing continuity of amateur equipment. It is only one of several tests described in (AS/NZS 3760:2010), but it is most relevant to ham equipment, especially so-called ‘boat-anchor’ equipment. Continue reading Earth continuity testing of amateur equipment

Revision of FoxDelta null modem adapter

FoxDelta supplies a null modem adapter with their FoxTrak tracker. The null modem is used only during configuration.

The adapter is supplied with hex pillars (jack screws) on both DE9 connectors, which prevents the adapter being plugged directly onto the FoxTrak, or onto a PC USB-RS232 adapter with pillars. Continue reading Revision of FoxDelta null modem adapter

Adjusting Foxtrak tx audio using an SSB/FM receiver exploiting Bessel zeros to calibrate the modulator

This article explains a method of setting the tx audio level of a Foxtrak using an SSB/FM receiver exploiting  Bessel zeros to calibrate the modulator. Whilst the Foxtrak is used in this example, the method can be used with any tracker or TNC that allows single modem test tones to be transmitted. Continue reading Adjusting Foxtrak tx audio using an SSB/FM receiver exploiting Bessel zeros to calibrate the modulator

AX.25 1200Bd AFSK FM – to pre-emphasise or not

Hams have used 1200Bd AFSK FM as the physical layer of AX.25 for decades, though with variable implementation quality.

Whilst the AX.25 packet networks of yore have all but died, the protocol is currently used with APRS, and so the related issues remain relevant… well as relevant as APRS remains. Continue reading AX.25 1200Bd AFSK FM – to pre-emphasise or not