Some time ago, James, VE6SRV, gave me his ICOM 24AT dual-band radio to use for the BEAR cross-band repeater, but noted that I would first have to repair it. (What a sneaky way to get his radio fixed for free!)

These pictures are of the radio after it was modified (and repaired) for use on the BEAR-2 flight.

Ready to fly cross-band repeater	Interior of IC24-AT
Components removed to save weight and/or reduce power consumption.
(Sorry James - I couldn't help myself! But don't worry. Believe it, or not, when your radio is no longer required for balloon flights, it can be put back together the way that it was.... Really!)

After about 30 hours of work I had James's radio operational. A lot of time was spent cleaning up previous repairs and damage done by someone without the proper tools, supplies or technique. The radio also required a lot of TLC (tender-loving-care) work. Like most handheld radios, it had been WELL USED. Then, as I was doing final testing, the micro-processor failed with a shorted protection diode on the PTT switch input pin which caused the radio to permanently transmit. It is a mystery as to what may have caused the failure. Was it simply old age and the diodes time to die or did it receive a static charge and fail in it's attempt to do what it was there to do? Anyway, a new micro was ordered, installed, and all is now well.

The 24AT is a very nice radio. I have repaired 3 of these radios and all had super receive sensitivity. I like the hardware design as it makes the 24AT a nice radio to modify for special applications which is why I just couldn't resist modifying the radio to reduce the squelch tail that was too long for my liking while cross-banding. I also eliminated the constant band switching and the delay introduced while the radio alternately checked both bands for signals as we only required UHF to VHF cross-band operation. This also eliminated any chance of repeater problems due to APRS VHF transmissions being detected.

For our next flight I plan to learn how to write PIC software so that the front half of the case, keypad, LCD and the 24AT control board can also be removed and replaced by a small PIC with software tailored to our exact needs.

October 28, 2004 - I have received several emails from individuals with 24AT's that found this page while searching for repair assistance. If a search directed you to this page, or however you ended up here, please see my note on the BEAR Home Page regarding the next BEAR mission and 24AT's.