Albrecht SS485
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:
25.165-25.605
25.615-26.055
26.065-26.505
26,515-26,955
26,965-27,405
27,415-27,855
27,865-28,305
28,315-28,755
28,765-29,205
29,215-29,655
To transmit / receive on all of the 400 channels it is necessary to adjust the VCO.
April 24th, 2005 at 4:48 pm
Is there a mod for the vco? I did the mod and it worked, but i can only get about 160 channels worth of bandwidth. thank you. Dan spooby1dan@aol.com
April 24th, 2005 at 7:10 pm
I’ll check all of my notes and see if I can find a mod for you. If so I’ll post it here as well.
May 4th, 2005 at 5:26 pm
do you have a mod for sy-205 into a htx-10
May 15th, 2005 at 1:50 pm
Inside the case of the 485 you will see a little metal box with some type of waxy sealer.I believe it is on the left side when looking down on the board,which would be the bottom of the radio if i remember correctly. This is the voltage controlled oscillator . inside is another small metal box ,which i assume is a variable inductor, and you adjust it by turning the small carbon core on the inside.(be careful when doing this. make sure you clean the waxy stuff out good or else the carbon core will break) By adjusting this in and out you can make your operating range move up and down. But the way the radio shack TRC-485, like mine ,is tuned ,maximum ssb power and modulation quality is found from 26.965 on up. Good luck and happy talking . 9YB335 prince edward island
May 16th, 2005 at 5:25 pm
CORRECTION
there is no bigger metal box out side the variable inductor .only the variable inductor amoung many small resisters covered in the waxy substance. Sometimes my memory fails me .
9YB335 PEI
October 2nd, 2005 at 7:37 pm
I tried adjusting the vco but it only moves my range of channels up or down. i cant get full coverage. is there a mod for the vco?