433.8 MHz the New APRS Kid on the Block?

Automated Packet Reporting System or APRS is a really useful aspect of the Amateur Radio hobby. However, since learning that APRS on the usual 2m frequency 144.800 MHz is illegal within 50Km of GCHQ at Irton Moor in the UK I was forced to look for alternative frequency allocations or face the fact that I would never use my shiny new Yaesu FT3 for APRS ever again!

In May I met Roy M0ORH a repeater keeper from Hull. He was a bit shocked also to learn that APRS in the area was all but impossible on 2m. Within hours he had sent me a message to a little line in the RSGB band plan for 70cm. Reading “433.800 MHz for where 144.800 MHz cannot be used” see RSGB band plan external link below.


Turns out this 433.8 lark was considered before by M0PLT in his article https://www.m0plt.me.uk/aprs.php where he talks about adding 433.800 MHz to his cross band I-Gate. The idea being that 433.800 MHz is actually a much more useable frequency for hand portable stations due to antenna size.

Crossband repeater: The FTM-400 can act as a cross-band repeater. Curiosity and a licence to experiment led me to this test. With the APRS modem disabled, and the TT4 powered down, it is possible to establish a cross-band AFSK repeater function between 144.8 MHz and 433.8 MHz. Hand-held radios set to operate APRS on 433.8 MHz will have their traffic repeated to 144.8 MHz, and iGate/repeater and other station traffic will also repeat from 144.8 MHz to 433.8 MHz. This was idle curiosity and probably does not have a real-world application. Most hand-held radios with APRS tend to be dual-band. The limitation to APRS on a hand-held is the aerial and how close you may be operating (riding a Mountain Bike, for example) to iGate/repeater systems.

Source : https://www.m0plt.me.uk/aprs.php

I duly applied for an obtained an NoV for 70cm and voila! The coverage is reasonable I hope it will improve over time. I think the intention for me of covering 10 miles is very possible with the right antenna. So.. could I tempt you to switch onto 433.800 MHz? I hope so! If more I-Gate owners added 70cm to their existing NoV then the UK would have an envious coverage for portable stations able to carry a vast amount of services from APRS SMS to emergency location positioning.

My I-Gate is MB7RWV the homepage is here.

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