{"id":50875,"date":"2021-11-15T08:18:05","date_gmt":"2021-11-15T12:18:05","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=50875"},"modified":"2021-11-15T08:20:09","modified_gmt":"2021-11-15T12:20:09","slug":"radio-mods-unblocking-the-yaesu-frg-8800-frequency-coverage-limitations","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2021\/11\/radio-mods-unblocking-the-yaesu-frg-8800-frequency-coverage-limitations\/","title":{"rendered":"Radio Mods: Unblocking the YAESU FRG-8800 Frequency Coverage Limitations"},"content":{"rendered":"

Many thanks to SWLing Post contributor,\u00a0Paolo Viappiani (SWL I1-11437)<\/a>, who shares the following guest post. <\/em><\/strong>Note that, as with any radio modification, perform this operation at your own risk<\/strong>. This is a very simple mod, but if you feel it might be beyond your skill level, consider hiring a radio technician to perform it on your behalf:<\/em><\/p>\n

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Unblocking the YAESU FRG-8800 Frequency Coverage Limitations<\/h1>\n

by Paolo Viappiani<\/strong><\/p>\n

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Figure I: An unblocked FRG-8800 receiver tuned to 29.999.9 MHz.<\/p><\/div>\n

Introduction<\/h1>\n

It is well known that some receivers produced in the last decades of the last century suffered from a limited frequency coverage due to legislative restrictions in force in some countries (Germany, Australia, etc.).<\/p>\n

In particular, in Germany it was forbidden to listen to HF frequencies higher than 26.1 MHz, while in other Countries shortwave were not allowed to receive frequencies below 2 MHz.
\nThese restrictions led most radio manufacturers to produce \u201cblocked\u201d versions of their HF receivers in order to satisfy the various national requirements; almost classical examples are the world renowned SONY ICF-2001D and the PHILIPS D-2935\/D-2999 portables.<\/p>\n

The blocking\/unblocking procedure of some frequency bands was quite simple in microprocessor-governed synthesized radios: usually it was sufficient to add (or remove) proper jumpers in the vicinity of the microprocessor to perform the task, and the correct procedure was often covered in the Service Manuals or in specific Technical Bulletins; in any case plenty of information can be found on the Internet.<\/p>\n

With some exceptions, obviously, and the YAESU FRG-8800 just represents one of them: if you search on the original manuals or on the Internet, you will find about NOTHING on the specific matter\u2026<\/p>\n

Some More Details<\/h2>\n

In the User Manual of the YAESU FRG-8800 Receiver it is specified that it was manufactured in different versions according to government regulations (look at Figure A below), but on its Service Manual nothing is specified on the various frequency blocks or on how to remove them.<\/p>\n

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Figure A<\/p><\/div>\n

As I recently stumbled upon a \u201cblocked\u201d FRG-8800 of the German version and I needed to remove any frequency limitation, I and my close friend Gigi Lombardo of Bassano del Grappa, Italy, started a deep research on the Internet (with practically no results).<\/p>\n

I also subscribed to a Facebook Group (Fox Tango International) and posted my question, receiving some answers from the members Andy Jack and from Simon N. Poysden (many thanks to them all!).<\/p>\n

In particular Andy invited me to contact Guy Desimone VK3GUY, the Australian Repair Workshop for Yaesu Japan.<\/p>\n

Unfortunately, Guy was not able to help me and he promised to ask Yaesu Japan about the specific matter.<\/p>\n

At the same time, Gigi Lombardo continued his search, he also contacted some German hams and at last obtained a very interesting reply from Jurgen, DF5TY (many thanks Gigi and many thanks Jurgen!).<\/p>\n

Jurgen suggested to look for some pins near the FRG-8800 microprocessor and to remove the short circuit among them\u2026 and he was right!!!<\/p>\n

The solution to an annoying problem<\/h1>\n

In order to remove any frequency limitation in the YAESU FRG-8800, please perform the following steps carefully:<\/p>\n

1)<\/strong> Remove the bottom and the top cover of the unit, in the top chassis of the FRG-8800 is located the PLL unit (Figure B below).<\/p>\n

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Figure B – FRG-8800 PLL board<\/p><\/div>\n

2)<\/strong> Precisely locate the TPO-16, TP-17 and TP-18 positions (look at Figures C and D); consider also the FRG-8800 PLL schematic (a detail in Figure E).<\/p>\n

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Figure C – FRG-8800 PLL board detail<\/p><\/div>\n

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Figure D – FRG-8800 PLL board drawing detail<\/p><\/div>\n

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Figure E<\/p><\/div>\n

3)<\/strong> Carefully remove the screws that fasten the PLL board to the chassis (and the \u201cRemote\u201d connectors on the rear panel) and reverse the board in order to access its track side.<\/p>\n

4)<\/strong> Identify the TP-16, TP-17 and TP-18 positions (look at Figure F).<\/p>\n

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Figure F – FRG-8800 board track side detail<\/p><\/div>\n

5)<\/strong> Remove (unsolder) any short among TP-16, TP-17 and TP-18 (Figure G shows a 25.999,9 blocked unit, Figure H shows a fully unblocked unit; in Figure I is represented an \u201cunblocked\u201d FRG-8800.<\/p>\n

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Figure G – FRG-8800 PLL board track side detail (26 MHz blocked)<\/p><\/div>\n

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Figure H: FRG-8800 board track side detail (receiver fully unblocked).<\/p><\/div>\n

6)<\/strong> Carefully reinstall the top and the bottom covers of the radio and enjoy your unblocked receiver.<\/p>\n

Final Notes<\/h1>\n

It\u2019s also worth to noting that:<\/p>\n