R5 Certain Frequencies are being skipped on my R5 - 380 MHz

[rescue161]

I just got this on Ebay and it is in excellent shape. Is there a way to make it receive 380-382 MHz? I get to 379.8875 and it jumps to 382.1000. Why? I have reset it using the Partial Reset and the All Reset and it still does it. It also skips over the old cell freqs and that is fine, but I need to monitor 380-400 in FM.

It does pick up other frequencies perfectly and can receive very well.

 

[wd9ewk]

Hi!

The gap you referenced appears to be one of the several gaps present in the Japanese version of the IC-R5. From the Japanese IC-R5 manual, this is a screenshot showing the coverage in that version:



For most receivers and amateur transceivers made for the Japanese domestic market, the frequency ranges are hard-coded in the radios, and cannot be modified.


Good luck!

 

[rescue161]

Well, that just sucks. I got the US manual with it, which did not show those ranges. Is there a way to change a jumper to convert it to a US model? Otherwise, I'll have to sell it. I only care about normal VHF/UHF/380-400 and 7/800 public safety. I bought it for its small size for fox hunting with a TDOA antenna array. Any help is greatly appreciated.

 

[rescue161]

I see there is a mod for the Japanese version to open it up, but I'm being blocked from seeing it on the mods.dk website. Can anyone assist me? Thank you.

 

[rescue161]

I wasn't being blocked. I guess my old account got scrubbed, so I had to re-register. I am able to see the mod, so I'll investigate tomorrow to see if I can mod it to receive the missing 380 MHz portions. The article on mods.dk is not very detailed and does not give a description of the component that needs to be removed or the part number and gives a very crude drawing of what needs to be "taken" as the article describes. I guess I'll find out. If it works, I'll post pictures and details. If it doesn't, I'll put the component back on the PCB.

Edit:
I opened the back cover and the resistor that needs to be removed to expand the frequency coverage was already missing. I guess the person that removed the resistor did not finish with the mod. You also have to press the FUNC, SQL and BAND buttons while powering it on. Now it covers the needed spectrum in the 380 band as well as other parts, I'm sure.

 

[rescue161]

Upon further investigation, being that mine is a Japanese model, it has the "resistor" which is actually a jumper, labeled W6 in the service manual. This jumper is on the logic board which is tied to IC1, Pin 81. There are several other jumpers that are on other areas of the board, but all come back to IC1. They are W2, W3, W4, W5 and W7. The service manual details which jumpers are for which region. W6 is the only jumper that is accessed without taking the logic board out. W2, W3, W4, W5 and W7 are on the opposite side, but are all together and are tied to IC1 pins 85, 84, 83, 82 and 80 respectively, so W2 is tied to pin 85, W3 is tied to 84, etc.

I don't have a USA or any other version to test, but I'd imagine that if your USA version has a W3 & W4 jumper and is missing jumper W5, you may be able to swap them around and press FUNC, SQL and BAND while turning on and then you may have the entire range. Please do so at your own risk. If I had a USA version, I'd try. I was going to pull out my logic board to see which jumpers are populated, but the SMA spanner nut has Loctite all over it and I do not have a spanner wrench that fits that particular nut.

Here are some extracts from the service manual. Note that W6 is not mentioned in the description of parts, but is shown on the logic board.