RT85A FAQ & Files

by Mark, VK3BYY
Melbourne, Australia

This page is a collection of information on the AWA RT85A.
Most of this information applies specifically to the A-model UHF low-band units that were used by the Royal District Nursing Service, Melbourne, Australia, and found their way into the amateur 70cm service around January 2002.

AWA RT85A personality data (configuration bits)

Tuning the RT85, RT85A, & RT85C to 70cm

EPROM Files:
These files operate correctly ONLY in the RT85A UHF (403-420MHz) sets that have been re-tuned to the 70cm amateur band (Transmit 433-440MHz, Receive 438-440MHz).
  The 2716 EPROM may work with the original RT85 Z-273 module, however the personality data is not correct for the standard 85 model and may cause unexpected operations.  The 2764 EPROM will not work in the RT85C model.

NERG78K8.zip - NERG 70cm 2764 EPROM ver 7.8 for RT85A
NERG78K2.zip - NERG 70cm 2716 EPROM ver 7.8 for RT85A
NERG 70cm ver 7.8 Frequency list and notes (PDF)
NERG 70cm ver 7.8 Frequency list (Excel xls)

nerg70k8.zip - Old NERG 70cm 2764 EPROM ver 7.0 & bug patch file (NERG70k8.zip)

Old NERG 70cm EPROM frequency list

Reverse Engineered files:

Disassembled 2764 RDNS RT85A EPROM (RT85A_64.A05)

Disassembled AWA RT-85A/A Mask ROM (RT85AROM.A05)

Beware - although the SELCHA software can program the channel data for the RT-85A, it does not set up the personality data or scan channels correctly.  Some hand editing of the EPROM data is generally required.

The auxillary port on the RT-85A doesn't always work as expected for applications such as packet radio or IRLP:
   One reason could be that a non-standard pin numbering scheme is used - consult the manual carefully!
The other reason is that some pins may have been rewired for special applications.  The PTT line was used for an emergency button in the RDNS radios.

Still to come:
Circuits for the HD63056/2764 controller board

A little history behind the RT85 linage

Other useful favourite links:
Email me at this address after removing obvious stuff to confuse the spammers: replace-all-this-rubbish-with-my-callsign@qsl.net
Last updated: 10/10/2007