1. 1750Hz tone access, carrier maintained with no talkthrough limit.
2. 1750Hz MCW identification every 5 minutes with beacon mode when not in use.
3. Two pip five second re-access period.
4. Optional callsign at the end of the re-access time.
5. 20dB audio mute on tone burst detection.
6. Selectable squelch sense.
7. Low impedance audio output of several volts.
8. Remote closedown.
9. Low power consumption on a small size PCB.

In January 1982 was published a small "piggy-back" addition board, which added an optional talkthrough limit, optional callsign on access, and a self timing 1750Hz notch filter to replace the tone gate.
The KISS principal was always taken into consideration, and Tony has had boards made up and has helped out many repeater groups.
In November 1983 the Mk.2 was described in RadCom.
It was the same physical size and the same interconnection data, indeed it was intended as a direct replacement for the Mk.1.
This version was microprocessor controlled and had its operation determined by software, so a group could tailor performance and facilities exactly to their requirements, as long as they had someone able to modify the program.
The main enhancements of the Mk.2 were as follows:

1. Tone and carrier or tone and audio access.
2. 1750 and 875 ID tones.
3. HI/LO RX input frequency and battery operation indication.
4. Manual and automatic mode operation.
5. One in four beacon callsigns contains a long ID message.
6. Four unused input lines, which could be used for remote control or CTCSS.

Since its publication, the Mk.2 has proved much more popular than the Mk.1 and some 130 PCB's have been supplied, and many EPROMS blown with the GB3HH/GB3US program.

The South Yorkshire Repeater Group are now offering other groups who use or wish to use the G3RKL Mk.2 logic, a 10 day turn round repair service to the groups faulty board providing the board meets their standard.

Further information from the author, G3RKL (QTHR) not ukrepeater.net