Motorola Syntrx.

In 1997 I designed an eprom adapter board to suit the syntrx. The schematic for these has been around in many forms for a few years but no one had put a board on the market. I sold my boards at cost to help local hams and some commercial companies. My board was labelled with a copyright notice because I think little of others ripping my artwork for commercial gain. At this point I need to say that the company that reprinted my layout is not at fault and that RCS radio in melbourne is a highly respectable company that has been around for many years they would have not been aware that the client was not the copyright holder. The really annoying thing is that If that guy had asked me for the originals I probably would have given them to him.

If you buy one of these on ebay or at the Wyong field day and it has RCS printed on it then you are unfortunately lining the pockets of someone who does not have the right to reprint and sell my artwork. The worst bit is that when I confrunted him at the Wyong field day where he had a stand dedicated to selling these, His ony comment was that it's a simple enough design of little significance.

Were that the case he would have drafted his own !

Heres a picture of my adapter board printed for me by Veltek in adelaide (1997)

This is how it seats in the Syntrx with the EPROM directly above the CPU

Anyhow, I probably wont make any more. and here's why

The syntrx toggles the VCC line on the eprom to read (remember that the original prom was an old bipolar). My board replicates that which means it wont work with CMOS EPROMS.

one of the members of tha Albury amateur radio club was on the team that designed the Syntrx radios way back (He ought to know a thing or two). Anyway, he has laid out a very nice version that has an added transistor to invert and divert the enable line to the chip select where it belongs.

I believe that the Albury club is selling them to raise club funds. If I track them down I will put contact details here.

Look Mum No Mike!

Yes It has been done before. But I like the idea of placing all of the mods inside the radio. Here is my simple and somewhat dodgy modification to allow the Syntrx to be used For APRS. The mod does a number of things as follows.

1. Present enough current to the microphone power regulator to convince the radio that the power switch is on.
2. A resistor to convince the PTT line to stay off unless commanded by the TNC
3. A resistor to set the speaker volume control for monitoring purposes.
4. Separation of PTT from mic line.

Heres the sequence of modifications to acheive the goal:
1 placement of a 120R resistor between R415 (+5volt side) and P107-5 convinces the radio that it should be on
2. Placement of 1 10K resistor between the same +5v source as above and P107-6 Holds PTT high.
3. Removal of Resistor R424 isolates the cpu display data from the microphone connector.
4. Removal Jumper JU405 isolates the PTT from the Microphone hi line on the microphone connector (P102-6)
5. Placement of a wire between P107-6 and the end of R424 that goes to P102-4 makes P102-4 the PTT line.
6. Placement of a fixed or trimmer resistor between R79 and ground sets output level.
7. The volume set resistor can be placed at the TNC end if reqquired it comes out on P102-9
8. Placement of a link between JU402 and JU401 (the ends nearest to the CPU)

 

The jumpers to remove are in the middle of this picture	Just one leg of the resistor is lifted

 

Syntx Mic connector	Usage	Colour (The Syntrx lead is standard)	Din Connector (Standard-TNC)
P102-4	PTT (was display data)	Slate	3
P102-5	Mic switch data	White	unused
P102-6	Mic Hi	Green	1
P102-7	0V	Black	2
P102-8	+5V	Red	unused
P102-9	Volume control	Blue	optional
P102-10	RX Audio	Orange	4

Here is my Syntrx APRS box.

This consists of a Syntrx and an old TNC-2, all powered by a battery backed Switchmode Power Supply.

Syntrx Roms.

I Will have these roms avaliable soon for UHF and VHF to suit radios with type A and type B CPU's.

Very robust mobile radio's. I will have these files ready soon soon!

1	70cm Ham
2	Channel list for 70cm ham
3	2m Ham	SYN2MTR.rom
4	Channel List for 2m ham. This is the same as the "ACT RED" file for FM900 radios
5	VHF APRS single channel Rom on 145.175	SYNAPRS.rom
6
7

SYNTRACKER!

Here's my current project to make a robust APRS system where the GPS engine, The Tiny track and the Max 232 line drivers are all installed insid the Syntrx radio.

Again, Here is an over cooked and very fiddly job where the effort does not nesecarily justify the final product. Because it is my hobby I can't be accused of going too far. It would have worked just as well if it was on vero board and installed in a tupperware box but it's in the building that I derive my kicks!

You can see the GPS engine is mounted on the left on carefully cutout brackets that use the mounting points for the original Motorola selcall board. The Tiny Track Clone (A board that I laid out) is positioned above the Micro.

The original connector block was removed and gutted to make way for a DB15 and the SMA connector for the GPS antenna. The switch to the right toggles the serial lines so that in the normal position the cable provides GPS data to a laptop for OZI Explorer (tm) etc.. and in the other position allows configuring of the Tiny Track. The cable also provides all led indicators up to the vehicle console.

The Max232 "not shown" also provides programming for the Syntrx plus via the same db15 "NO RIB NEEDED" Thats the cool bit

The cable breaks out into the radio nicely

Here are some of the assembly pic's

More pics will follow showing the final rats nest with the MAX232 board etc..

Still cool but not as neat as I would have liked.