The Motorola Radius M100 radio that was built to last!

The Motorola Radius M100 is a classic two-way mobile radio introduced in the late 1980s. It earned a reputation for being rugged and "built to last" due to its heavy-duty die-cast aluminum chassis, high-grade commercial internal components, and compliance-level structural toughness designed to withstand harsh industrial and vehicular environments.

Design and Durability

• Tough Chassis: Built with a thick metal frame that dissipates heat effectively and protects internal logic and RF boards from physical shock and vibration.
• Industrial Use: Widely deployed in commercial fleets, public safety back channels, and construction sites where equipment faced constant movement and dust.
• Simple Controls: Offered a straightforward, no-nonsense interface (often 2 channels) that reduced mechanical failure points on the faceplate. 

Technical Legacy and Limitations

• Power Output: Typically pushed an honest 25 to 40 watts of RF power, depending on the specific VHF/UHF split.
• Programming Hurdles: These vintage units rely on legacy DOS-based Radio Service Software (RSS) and a dedicated Radio Interface Box (RIB), making modern programming a notable challenge for hobbyists. 

I have a Motorola Radius M100 VHF radio connected to the ZS1I AllStar HUB Node in Mossel Bay since 2016.  This radio is now running full output power for 10 years as a linked radio to the HUB and is connected to world wide Echolink, AllStar and DMR networks seven days a week.  This radio is being used for what it was never intended for.  It was designed as a mobile radio and not as a full time simplex or repeater radio.

I am flabbergasted that this radio is still working the way it did 10 years ago without skipping a beat taking into account the heavy duty cycle it goes through, sometimes transmitting for 1 hour or longer.  We need to take into account that this radio was introduced in the late 80's  and is a real brick of a radio.  Another important factor apart from being rugged and built to last is curtailing the heat created by the pre-driver, driver and final transistors.  Heat can be the enemy of many radios.  Incorrect heat distribution and high temperature can cause radios to fail.  In this case I chose to install an outboard computer fan (80mm x 80mm) to the heatsink of this radio.  I also installed a homebrew fan controller which was described in my article available HERE.

The fan does not run all the time but comes on when the radio is in TX Mode for longer that 30 seconds depending on the temperature in the shack an whether it is winter or summer. 

I constantly monitor the radios's output power as well as SWR with an inline SWR and Power Meter combination.   So far I have not detected any indication of lower output power or higher SWR than first measured when I installed the antenna.  Apart from making a COS modification to the radio nothing else was modified or fixed.  

The Motorola Radius M100 is an ultra-reliable, vintage analog mobile transceiver built like a tank.  It is widely praised by retro radio fans and amateur operators as a classic "no-nonsense" workhorse.  Housed in a heavy-duty metal chassis, the M100 takes physical abuse, high vehicle vibrations, and extreme field environments far better than modern lightweight plastic radios. Features exceptionally crisp, clear analog receive and transmit audio that easily cuts through noise Delivers a solid 25 watts of power (depending on the specific VHF/UHF band split), making it great for base stations or mobile setups. Most base M100 models support very few channels/modes (often just 2 channels) unless upgraded with specific logic boards.

Obsolete Programming - Requires an archaic DOS-based computer environment, a Radio Interface Box (RIB), and specific Radio Service Software (RSS like RADMBL) to change frequencies. 

Final Verdict: If you find a working unit cheap, the Motorola Radius M100 is a fun piece of radio history and a bulletproof analog link radio to have in your shack.    Let's see if this radio will last another 10 years from today forward.

Thank you Motorola for making such quality radios!! 

Images:  (Click on image for larger view.)

 

ICASA investigates illegal radio transmissions in Germiston

Image:  AI

Investigation targets alleged illegal use of amateur radio frequencies in Germiston.

An investigation led by the Independent Communications Authority of South Africa (ICASA), is clamping down on businesses operating illegally on amateur radio frequencies.

Read more HERE 

Once again the Internet has failed in the Southern Cape Area of South Africa

Image:  AI 

This is not going to be a moaning or groaning topic however I must admit that the lack of Starlink Internet is definitely felt in this fifth world country we living in.  For the past three days I have experienced sporadic Internet outages for whatever reason, this does not matter. Matter of fact is there is currently no reliable Internet service from my providers and once again let me rather not mention them.  What really matter is that there is really no alternative except amateur radio when the Internet fails.  Lots of talk about an alternative for Starlink which they say is going to be a South African Satellite Service Provider.  I can just wonder what is going on behind the scenes and how this so called "brilliant" provider is going to provide and alternative to Starlink with old satellites.  I have my thoughts about this but I will keep it to myself. Time will tell what this third world service and outdated satellites will provide as opposition to Starlink.  I doubt it this fifth world country is able to compete with Starlink.  Enough!!

Let's see what the future holds but until then I presume we must be satisfied with a firth world Internet service in this country.

Finally:  I still say we as radio amateurs need to find alternatives for the Internet and don't tell me it is HF Radio or VHF/UHF Repeaters.  I am working on a few projects that if successful will be used as alternatives for the Internet.  What are you doing to find alternatives?