ICOM 705 åben på 70 MHz RX

Der er rigtig meget godt teknisk stof på den russiske hjemmeside radiochief.ru. Emnerne er hyperrelevante og oftest graver de et spadestik eller to dybere i både radioer og teori end man ser andre steder. R6A Денис har splittet en IC-705 ad og fundet ud af hvordan man åbner den både i RX og TX på 70 MHz samt MARS. Desværre er der ikke noget TX output på 70 MHz, det er blokeret i softwaren p.g.a for mange uønskede udstrålinger, men måske er der også nogen som finder en løsning på det?

Læs artiklen fra R6A nedenfor. Det er en blanding af maskinoversættelse og mit eget efterhånden noget rustne russisk.


Inside the Icom IC-705 + MARS MOD (open to transmit)


It’s time to look inside the new ICOM IC-705 transceiver and find out what ICOM has hidden in the depths of this wonderful black box in every respect. It was very interesting for me to see what is inside a modern SDR transceiver and I tried to photograph everything in detail and show you.

I tried to figure out which components are used in the ICOM IC-705 and wrote my comments to the photos. If you make a mistake somewhere, correct me in the comments. Alas, I have neither a diagram nor a service manual with which to check, but I hope that over time these materials will appear for me and clarifications can be made.

How to Open ICOM IC-705

It is very simple to open the transceiver. To do this, you will need some good Phillips screwdrivers type PH in different sizes. It is desirable to have a set.

Disconnect the battery and unscrew 4 screws at the corners of the transceiver case, as well as two screws at the top and bottom. This is where we need a good screwdriver of the correct size, since the top and bottom screws sit on the blue thread lock. You will have to make some effort to unscrew them. When all screws are removed, the front panel can be easily separated from the transceiver body.

Carefully disconnect the two cables and move the front panel to the side.


Note that all wide signal loops are shielded, which is of course a plus.

We turn off the screen and along with it the receiver board.

Installation, traditionally for ICOM, is very neat. There is no uncleaned flux. Wherever necessary, the manufacturer has used screens. Let’s go through the components.

The processor that controls all the peripherals in ICOM IC-705 is RENESAS R7S721000VCFP. It is a powerful ARM processor with a Cortex-A9 core. 400MHz frequency. Built-in memory 10MB.

As an FPGA (FPGA), which processes radio signals digitized using an ADC, a rather powerful FPGA from Intel / Altera is also used – Cyclone 10 10CL025ZU256I8G. For comparison, the ICOM IC-7300 also uses Intel / Altera’s EP4CE55F23I7N FPGA. The ADC used to digitize the incoming radio signals is from Analog Devices AD9266. 16-bit ADC, in fact, there is most likely the same as in ICOM IC-7300 14-bit.

The DSP is ADSP-21478 from Analog Devices.

Another DSP. TMS320C55 from Texas Instruments. A block with diodes is located next to it (circled in red). The photo shows the Japanese version. With the help of these diodes, you can somehow open the transceiver for transmission. There is currently no information on how to do this. But if it appears, I will update the article.

Some more photos of the components of the main board of the transceiver.


ICOM IC-705 Wi-Fi transceiver module. There’s even a jack for an external antenna 🙂

ICOM IC-705 transceiver Bluetooth module.

Under the board, we have a metal shield screwed to the chassis with a variety of screws. We unscrew and observe the low-pass filter board.

We remove the filter boards and get to the heart of the transmitter.

The IC-705 transmitter is based on an AFT5M31N transistor. Such a transistor can easily deliver 30 watts, but it is strangled to 10 watts, which is generally correct.

Some more photos of ICOM IC-705 internals.

We open the ICOM IC-705 transceiver for transmission (only for the European (EU) version)

Long-awaited MARS MOD for the European ICOM IC-705. The transceiver is opened for transmission on the following sections:
TX: 1.600 – 54.000 (Yes, on CB too  👌🏻)
68.000 – 74.800
118.000 – 174.000
400.000 – 470.000
ps (no output power at 70MHz). Thanks to EU6AB and XE1SGT for the information. Unfortunately, none of this will work on the Japanese version.

Good luck to everyone, 55, 73!

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