Icom: IC706 2M 146MHz limit

[snoack321]

Hi all I have an original IC906 from Japan and HF bands work just fine. However I’ve run into a roadblock setting up 2M repeater in US in that rig stops at 146 but the repeater I need to connect to (in US) is at 147.060!

Im I just missing a config or is there regional variation on 2M such that 147wasn’t supported and most importantly is there a hack/ fix I could apply to extent 2M on my unit to 148?

Thanks

Scott / KN6UTO

 

[mmckenna]

Different ITU regions/countries have different bandplans. Many countries only have 144-146MHz.

You may need to see if there's a way of changing the settings to whatever gives it USA frequency plan.

 

[snoack321]

Thx that’s exactly my situation and I’ve also officially asked ICOM USA for answer. Not holding my breadth for a positive answer though!

 

[merlin]

Surely there are some ham mods online to fix this.

 

[snoack321]

Surely there are some ham mods online to fix this.

I’ve googled and googled till my eyes googled and so far nothing. I suspect it’s not a hardware limitation (no diode to unsolder) but a firmware limitation and since there is no firmware update feature for the original 907 you would need to reprogram the chip. I have all the tools to do that except I don’t have the firmware code and if the chip is locked (which I assume it is it is impossible to clone/copy).

However, I’m an optimist and hoping someone will say it’s easy dummy to open up 147MHz in US you just …

 

[AK9R]

I have an original IC906...

I've never heard of an Icom IC906. Do you mean IC-706?

You may need to see if there's a way of changing the settings to whatever gives it USA frequency plan.

It may not be possible. I once owned a Japanese-spec Icom ID-31 that was locked to the Japanese band plan. There was no keystroke sequence, firmware change, or hardware mod that would open it up from the Japanese band plan. I suspect that Japanese communications rules strictly prohibit out of band transmission and radios sold for the Japanese market ensure those prohibitions.

Thx that’s exactly my situation and I’ve also officially asked ICOM USA for answer. Not holding my breadth for a positive answer though!

If the radio wasn't sold for the North American market or handled through Icom America, I would not expect them to help.

If you are talking about an IC-706, you might be able to find an otherwise dead 706 on the used market and transfer the CPU to your radio.

 

[snoack321]

Yes sorry IC706

Here is response from IC North America,

“…But to answer your question for our other products a JDM radio cannot be made to cover the North American bands, and visa versa. The radios are hardcoded to their regions band plan.”

 

[prcguy]

The 706 should only be hard coded via diodes or programming resistors. The factory is not going to give you a straight answer on a topic like this.

I've had the original 706 and a mod gave me very wide transmit and receive including VHF. Here are some discussions on modifying the radio and it looks like the last info in the second link discusses the big mod that widens VHF and I sort of remember having to do something like that.

Icom IC-706 Modifications

Icom 706 mods

Yes sorry IC706

Here is response from IC North America,

“…But to answer your question for our other products a JDM radio cannot be made to cover the North American bands, and visa versa. The radios are hardcoded to their regions band plan.”

 

[snoack321]

The 706 should only be hard coded via diodes or programming resistors. The factory is not going to give you a straight answer on a topic like this.

I've had the original 706 and a mod gave me very wide transmit and receive including VHF. Here are some discussions on modifying the radio and it looks like the last info in the second link discusses the big mod that widens VHF and I sort of remember having to do something like that.

Icom IC-706 Modifications

Icom 706 mods

Thx prcguy that is exactly what I was hoping and searching for! I have the Service Manual with large circuit print outs and following the ‘yellow wire’ mod now. Thx again.

 

[snoack321]

Thx prcguy that is exactly what I was hoping and searching for! I have the Service Manual with large circuit print outs and following the ‘yellow wire’ mod now. Thx again.

I applied the yellow wire mod, did cpu reset but still can’t get above 146MHz. Will double check work tomorrow but I believe I followed directions. See pics

 

[prcguy]

I think the yellow mod only bypasses a filter to improve reception above the amateur band and the radio would need a US or MARS mod type coverage to receive above the 145MHz Japanese version. I suspect the difficult mod shown in one of my links would get you there but its way more than snipping a few diodes.

I applied the yellow wire mod, did cpu reset but still can’t get above 146MHz. Will double check work tomorrow but I believe I followed directions. See pics

 

[snoack321]

Right. I found a more detailed explanation and steps from this link and I’ll try but I still don’t know if my display head unit will dial past 146MHz!!

25-08-2001
(IC-706) To expand the band on the VHF portion

http://pi4oss.ham-radio.ch/Mods/All_ICOM_mods_from_mods_dk_in_ONE_file.pdf#page163

 

[snoack321]

Ok I applied the more complex mod for extended VHF see pic and … still limited on faceplate to 146. I may have enabled vhf freq above 146 but the faceplate will only allow me to run up to 146 before it rolls over. So I need faceplate enhancement to allow me to dial past 146…

 

[EricCottrell]

Hello,

The only way to get back the 146 to 148 MHz segment is to change the diodes that configure what version the radio is. Based on the table in the service manual, you want Version #5 (USA). The Japanese version is not listed, but is usually Version #1.

All the diodes are DAN222TL
D57 FRA DEN
D58 EUR FRA
D60 USA
D84 FRA
D85 FRA

The schematic shows the diodes above and to the right of IC25 (the main processor) on the main board. There is a W4 jumper that is installed as well to defeat SW-161. It appears the diodes are near the processor on the PCB.

One unknown is the diode configuration for the Japanese version. You need to compare what is on the board versus an USA version (D60 and W4 installed. D57, D58, D84, D85 removed). Hopefully you can use a removed DAN222TL to put in for D60.

73 Eric

 

[snoack321]

Hi Eric I suspect you are right and I just need to find out what makes a USA zone 5 logic board unique.

D60 apparently sets 50 MHz to low power and only in US. There is also a 50W/100W switch near it. I have D60 installed. I had D59 which sets cpu tx limit but removed it. D58/d57 not present. D72 and dd105 present.

I asked someone selling a 706 on eBay if 146 works and he said it was Japanese and to get it to work he had to replace the logic board which I assume is main board.

You’ve given me more to think about. Thx

 

[AK9R]

I asked someone selling a 706 on eBay if 146 works and he said it was Japanese and to get it to work he had to replace the logic board which I assume is main board.

This.

In my experience, Icom radios intended for the Japanese market are "hard coded" for the Japanese band plan. You can't change the band plan by changing diodes or resistors. You have to change the firmware or change the board upon which the main CPU resides.

 

[snoack321]

Hunting for US main board…

 

[EricCottrell]

This.

In my experience, Icom radios intended for the Japanese market are "hard coded" for the Japanese band plan. You can't change the band plan by changing diodes or resistors. You have to change the firmware or change the board upon which the main CPU resides.

That makes sense. I bet there is a Service Manual for it in Japanese. I have seen other radios where the part number for the programmed CPU is different based on the region.

73 Eric