Icom IC-705 Modification

Icom IC-705 Modification

How to modify the new IC-705 to 60m operation, extended VHF and UHF?

Well, first of all please note that any modification will be on your own risk – you lose your warranty! This mod isn’t complicated but you need to be an experienced electronically trained person. Don’t do this if you don’t feel comfortable.

What can be achieved?

The radio is normally blocked for CB, 60m, 4m, extended VHF and UHF – in short, it is only open for traditional ham bands in Europe if you purchased an European version.

Check 60m – no TX on 60m…..!

Icom IC-705 Modification

Some blocks tell you that even 4m can be opened. See what you will find “online”:

•    1,6 – 54 MHz (correct)

•    68 – 74,8 MHz (not correct!)

•    118 – 174 MHz (correct)

•    400 – 470 MHz (correct)

Let’s walk this through – you will need 20 to 30 minutes time if you have the right tools in hand.

1)    Remove the battery – disconnect from power!!! Very important!

2)    Locate the 4    screws on the back of the IC-705 (2 on left and 2 on right)

3)    Locate the 2    screws on top and bottom of the radio.

4)    Locate the 2    screws on top and bottom of the radio.

5)    Remove all 6    screws – be aware that the two on top and    bottom    are metric and locked with “Locktight” (blue). Use a matching screw driver!

6)    Carefully open the radio. Inside there are 2 silver ribbon cables.

7)    Disconnect both ribbon cables

Icom IC-705 Modification

Opened – both cables disconnected. Left is the front panel – right is the radio. Concentrate on the radio furtheron.

8)    Put the front panel aside – you will not need this.

9)    Carefully remove the small ribbon cable also (See green arrow below):

10) Now remove all 7 visible silver screws of the metal housing and put them aside and remove the shielding:

Icom IC-705 Modification

11) Now locate the grey thin coax cable and disconnect it (See green arrow below):


12) Once this is done you can flip the PCB with both ribbon cables connected into a vertical position and get access to the bottom side of the PCB. Pay attention, the board is still connected by 2 more ribbon cables, visible in the upper right corner on the picture above!

13) Locate the diode pad on the bottom side – there is space for 24 diodes in 3 rows (3 x 8):

14) Locate the 2 diodes shown below: (left one on bottom row – second right on mid row) -marked in “red”

 

 

15) Remove both diodes carefully (See both green arrows):

16)    Okay, get you a coffee – your work is half way done!

17)    Put everything together again……take your time – do it with care!

18)    Double check please: You removed 13 screws in total, one thin coax cable, one small ribbon cable, 2 big ribbon cables and last but not least the metal shielding….put them all back in.

19)    Once everything is completed again, connect the battery and test the radio on 60m – it should now transmit. Please note there is visible output on the spectrum, waterfall and on the power meter (See the 2 green arrows below):

20) Go to 4m and realize that the radio shows spectrum and waterfall when transmitting but NO signal on the power meter. It is still not working on 4m (See the 2 green arrows below):

The radio has now full HF (TX) coverage incl. CB frequencies, it does AM on air bands, extended VHF (including marine bands) and extended UHF as expected.

Done. Good luck and 73, Andy

About Icom IC-705:

Icom’s latest baby is a real winner – it offers HF, VHF and UHF all mode with 10Wout max (5W on battery). The radio is capable to connect via USB, Bluetooth, WLAN – has even D-Star on board incl. GPS.

The receiver shows nice performance – the tx has very clean IMD3. I pushed my amp with 10Win to about 1 KWout and could not notice any big increase of IMDs. Much, much better than most other qrp radios which should better not be connected to any high gain amp. First tests on HF got excellent reports – also via D-Star on VHF/UHF no problems at all. The radio worked right out of the box. If you own an Icom IC-7300 already this radio is mostly self-explaining.

Pros: Well, I like the build-in front speaker, the crystal clear display and the loudspeaker microphone which is included in the box like the powerful 1.880 mAh Li-ion. It has a very powerful CPU (fast display updates), noise blanker, noise reduction and a very good compressor (all fully programmable). Total weight is just 1,1 Kg. Last but not least: Very impressive build quality. Big bang for the buck!

Cons: Buttons are not illuminated and there is no build-in tuner – also no second antenna port (for VHF/UHF)

Current versus Power @ 13,8V – no battery used:

Andreas Duessler, DL6EAT – W6EAT

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