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Table of Contents
Simoco SRM9000
These radios have become popular with Radio Amateurs due the availability of a 66-88MHz version, making them ideal for use on the 4 metre band. They have come to our attention due to the reasonable availability/price of UHF models (~£55 on eBay) vs other radios such as Tait or Motorola which are hard to come by and often expensive.
One useful feature is stepped power outputs (1, 2, 2.5, 4, 5 etc) which might be useful for complying with ERP limitations without having to adjust factory calibration settings.
These still require further testing for 9600 baud packet radio
Models
A sticker on the bottom of the radio has a code printed on it to indicate frequencies. Watch out for models that don't cover amateur bands!
| Version | Frequencies |
| E0 | 66-88 |
| AC | 136-174 |
| TU | 400-480 |
| UW | 440-500 |
TODO: Finish this
Images
TODO
Modifications
TODO
Programming
To program the radio you will need a proper programming lead or a TTL level USB UART adapter. Check the pinout section below to wire it up.
FPP V5.86 and ran fine on Windows 11.
I was able to read from the radio without a Mic / Control Head, or doing anything in particular to switch the radio “ON”, however I got the warning “Radio does not contain a PMR configuration”, presumably because it's new out of the box.
Pin Outs
Microphone / Handset Connector
Note The Simoco documentation numbers the pins opposite to the general standard used for RJ45 connectors.
| Name | Pin | Comment |
| Tx-Data | 1 | Output (TTL Level). Low = 25mA sink to GROUND, High = 2k2 Ohm pull-up to 5v via a series diode. Diode Clamped to -0.6v & 5.6V |
| Rx-Data | 2 | Input (TTL Level). Low < 0.5V, High > 2.5VInternal 6k8 Ohm Pull-Up to 3.3V780 Ohm in series with diode protection clamped to -0.6V & 3.3V 780 Ohm in series with diode protection clamped to -0.6V & 3.3 |
| On/Off Input | 3 | Input. Low <5V, High > (Supply Volts - 1.5V) or O/C. Internal 6k Ohm Pull-Up to Supply Voltage. Diode Clamped to -0.6V & 18V. |
| Mic Ground | 4 | Connected internally to Ground. |
| +13.8V | 5 | Switched + Supply Voltage. 250mA Max Current. |
| Handset Audio (OP) | 6 | Output. AC Coupled (10uF) to 0/5V Op Amp Output245mV RMS (nominal) for 60% RF deviation of 1000Hz tone. 600 Ohm series Impedance, Diode clamped to +/- 5.6V. |
| Ground | 7 | Internally connected to -VE. |
| Mic Audio (IP) | 8 | Input. 40mV RMS at 1kHz = 60% RF Deviation. >1k series impedance, Diode clamped to +/- 0.6V. |
External Interface Connector
The SRM9000 has a male 15 pin D-Sub connector on the rear of the radio which is used for both power and data.
13.8v and Gnd are supplied to groups of 4 pins respectively. Individual pins on reputable D-Sub connectors are rated for up to 5A of current, so for programming and testing on low power you can probably get away with supplying power to one pin, at your own risk. Approximate current consumption is 145mA at idle.
The connector, looking into the radio
| Name | Pin Number(s) |
| -VE (GND) | 1, 2, 9, 10 |
| +VE (+13.8V) | 4, 5, 11, 12 |
| Speaker | 6, 13 |
| General Input (PTT/RTS) | 7 |
| General Output (CD/CTS) | 8 |
| Ignition Sense Input | 3 |
| Audio Input | 14 |
| Audio Output | 15 |