Albrecht SS485, Radio Shack TRC-485, Dragon TRC-485

The mod was translated from spanish, there may be errors in the translation, once I worked out how this mod worked I changed some of it to make it easier.
The mod is to increase the amount of channels of the Albrecht SS485,Dragon TRC-485 or Radioshack TRC-485 that originally comes with 40 channels from 26.965 to 27.405.

The mod is to alter the pins of the 80 pin microprocessor (Albrecht SS485=SY202, Dragon TRC-485 = SY201, Radioshack TRC-485 = HYU4011Q06 FP), so that the pins where either disconnected from the circuit (open) or connected to the circuit (close), for pin 31 (open), pin 32 (open), pin 33 (open), pin 34 (close) the radio then had 400 channels of transmission/reception.


To control the bands you must touch pin 3 of the CPU with pin 29 for one second.

You can re-wire the NB switch to do this (the NB button is connected between pins 3 and 28), this is easy to do, read on !

Refer to the diagram below to assist with the description:


1. Locate the track that comes from the NB switch (SW403) and connects to pin 28 of the CPU, and cut it quite close to the switch (between SW403 and SW405), but not too close, as you need to solder a jumper onto it on the switch side of the cut, (pin 28 is shared with the CH9 button (SW405), so disconnecting the entire track or cutting it after the CH9 switch WILL cause other problems !)

2. After cutting the correct track run a jumper wire from the cut track (on the NB switch side of the cut) to one side of the MODE button (SW404), this MUST be the side that goes to pin 29 of the CPU (the same side that also connects to SW406, the SCAN button), OR if you are not sure you can run a jumper wire directly to pin 29 of the CPU.

3. That is it, your done !


Bands available after the modification:


To transmit / receive on all of the 400 channels it is necessary to adjust the VCO.



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