Asides from participating in MARS or CAP activities, there can be plenty of different reasons to extend the transmit frequency range of an amateur radio transceiver. I for instance, like using my amateur radio gear as signal generator for various experiments. A few days back, I got an IC-706 MKII in to perform the MARS / CAP modification on it. To my surprise, many online instructions on how to do this were either presenting the outdated main-board or poor graphics. So here’s the high-resolution instruction for the newer versions of the IC-706 MKII with main-board (B5209Q).
First off, one word of advise. If you have problems working with surface mount parts, this modification is not for you. The one diode that needs to be removed, is extremely small. How small you ask? Well, take a look:
To get to the diode, set the IC-706 on the table (LCD facing forward), remove the lid, and disconnect the speaker. You should now see the following:
In the top right corner of the main PCB is the diode D2030 that needs to be removed for an extended transmit frequency range. Here’s the close-up view:
Simply remove the diode and re-assemble the IC-706. Yes, that’s it. The removal of a single diode will convince your radio to transmit out of band.
Westerhold, S. (2013), "IC-706 MKII Extended Tx Modification". Baltic Lab High Frequency Projects Blog. ISSN (Online): 2751-8140., https://baltic-lab.com/2013/09/ic-706-mkii-extended-tx-modification/, (accessed: October 3, 2023).
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