SRM1000
SRM1000
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Old but basic and simple, the Simoco SRM1000 was the first Tetra terminal I owned and is considered "first generation". They were first used on the Dolphin network (now closed down) under the model number d120.
The two main versions of this terminal kicking around on the second hand market are TT and TZ band.
The TT band versions are 380 - 400 MHz and are almost certainly ex-ambulance service.
The TZ versions are 410 - 430 MHz and are mostly ex - dolphin network devices.
SRM1000's are usually about 3 Watts output in DMO. Whilst operating in TMO mode, they have the ability to have the output power controlled by the network.
These terminals (like most Simoco / Sepura terminals) can be re-aligned. This offers the ability to run increased output power whilst in DMO mode. The most I have seen from an SRM1000 is approx 20 Watts.
SRM1000's also recognise the presence of DMO repeaters on a given talkgroup. They will receive calls FROM a repeater, but tend not to SEND calls through a repeater very reliably. It requires several attempts to get an SRM1000 to make a call through a repeater.
Power Connector
Telephone Handset
The car handsfree kit consists of a small microphone, a remote PTT switch and a small "jumper plug". All of these items plug into the rear of the control head. Whilst in this configuration, audio is routed to the loudspeaker which plugs into the main transceiver body. The jumper plug replaces the telephone handset on the rear of the control head.
Car handsfree Kit
The loudspeaker is balanced line, so has an audio signal and audio return. Audio return is NOT power supply / chassis ground, so do NOT connect audio return to ANYTHING apart from speakers or transformers!!
The microphone is the same.. so... do NOT connect audio return to ANYTHING apart from microphones or transformers!!
The PTT has +5V PTT and then a true, DC / power supply / chassis ground.
The practice of connecting mic ground, speaker ground and PTT ground together REALLY has to stop. It overheats the audio stage and WILL eventually cause damage.
Telephone handset
Control Head Cable
(click to open in new window)
The telephone handset can either replace the jumper plug from the handsfree kit, and run at the same time, or entirely replace the handsfree kit. If you have the telephone handset plugged in at the same time, the audio is still routed to the loudspeaker until the handset is lifted from its magnetic cradle. At this point, the loudspeaker is muted and audio is routed entirely though the handset.
The same things apply to the telephone handset as the handsfree kit, so do NOT connect audio ground to ANYTHING apart from microphones, speakers or transformers!!
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