Cables for ICOM ID-5100

I’m afraid that I might be in the same boat (or similar) as Jim, here’s my ID-5100a story:

I purchased what was marketed as the CI-V version of the DigiRig from as part of their ICOM-compatible kit that included the RJ-45+TRRS cable and CI-V version of the DigiRig.

When I hooked up the kit like this: ICOM[SP2+MIC] ↔ DigiRig[Audio_Jack]

…nothing would initially happen however when I tried to hit the Test CAT button in WSJT-x the radio’s PTT would trigger and start to transmit. I’d have to go as far as unplugging the USB cord from the PC to get the radio to stop transmitting. After having these initial difficulties basically getting any sort of CAT connection to connect to the radio through SP2 I opened up the DigiRig and discovered that I was sent the stock(?) version of the unit instead of the CI-V version.

Being the generally handy type I was fine making the modifications myself. I next cut the connections and added some solder as per the instructions found here:

This is my work, which has good continuity checks even though my blob isn’t the prettiest:

My PCs all see the COM ports as well as the Audio controller however I’ve never been able to get a working CAT connection from the ID-5100 in the ICOM[SP2+MIC] ↔ DigiRig[Audio_Jack] configuration.

While not everyone has the same use cases I was personally only in the race for CAT control of the ID-5100; I didn’t really need the audio side for digital or FM use, I just wanted to adjust my radio’s basic settings from my PC and I thought this was the hardware that would do it. Is there maybe another way I could accomplish my goal with the equipment I have in front me of? Maybe I can use the serial output of the DigiRig instead of the Audio port without the MIC cable plugged in? Please forgive any of these possibly basic questions as I’m still quite new to the CI-V concept.

PS- Thanks for all your development efforts along the way, the DigiRig is important hardware to the radio community and I’m personally happy you took the time to engineer it for the benefit of the rest of us!

Currently there is no off-the-shelve ID-5100 Digirig kit with CAT/CI-V support. This thread discusses the DIY option which involves customizations of Digirig and addition of a serial CAT cable.

The RJ-45 kit from Gigaparts only includes the audio/PTT cable and it is not marketed as CAT/CI-V capable kit. It provides minimum functionality required for operating digital modes, but no optional serial CAT control. Because serial port on Digirig is not used in this scenario, the serial port can be in any (default in this case) configuration.

If you are interested in complementing your setup with CAT control you will need a separate TRS/TRRS cable going between Digirig’s (correctly configured) serial port and your transceiver’s SP2 connector. Details are earlier in this thread. Although other operators confirmed that this works, I never have a chance to personally verify this setup.

Got my ID-5100 up on Winlink VARA FM today. Using a RJ-45 / TRS audio cable ordered from Digirig store, a USB C to USB A cable from Amazon, a HP Windows 10 touch screen mini PC from Amazon Renewed with digirig interface.

TRS audio cable from the digirig plugged into Speaker 1 Jack on the ID5100. Followed the Delaware County ARES setup instructions for the ID-4100. Be sure to download the Silicon Labs Digirig Driver CP210x USB to UART Bridge driver mentioned in the Delaware instructions. Audio control to VARA FM adjusted from the 5100 audio gain on the control head.

Cheers… KX7YT

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Congratulations! The suggestion to download the latest Silicon Labs CP210x USB to UART Bridge driver is also mentioned in the instructions on the Digirig site:

Troubleshooting Digital Modes – digirig

73 Constrainted

Hi very new to this whole hobby but am looking ar buying an icom 5100e but need to be able to set the frequency via serial port from PC. This thread looks like it can be done but could someone let me know what hardware / cables I need. Thanks

Your project you’ll need:

Thank you!

The issue turned out to be an issue with the RJ-45 on the Digirig Icom cable. It just wasn’t making contact to trigger PTT. Cut it off, crimped on a new one and it works fine now. Maybe these are non-standard RJ-45’s or they aren’t getting crimped correctly somehow?

Very new to the use of Digirig. I have the ID-5100 and would like to use the Digirig in a go box; however with the recommended cable connected to the radio’s mic connector this makes for the need for a mic-switch to allow going from Voice to Digital modes…is there another way?

Hello everyone.

I am a technology teacher in a secondary school and a radio amateur involved in schools where I carry out numerous educational projects related to amateur radio and in particular the international space station (see all my projects on my website :

For my projects, I’m about to buy a second-hand Icom ID 5100 because it’s the only solution I’ve found at a reasonable price. The aim is to no longer have to dismantle my fixed station and to no longer have to transport my old Yaesu FT-847, which I want to preserve.

I therefore need a radio that can be controlled by computer to correct the Doppler effect with Hamlib/Rigctld and transmi/receive APRS frames via the UISS software at the same time.

Can the Digirig interface do this?

From what I’ve read, I think so, but I need confirmation before buying the Icom ID 5100.

Thank you all for your answers.

Best regards, David.

the digirig ‘mobile’ has an audio device (soundcard) and a serial port.

my satellite station uses C-IV for remote control
IC-821h is an all mode satellite rig

obviously overkill for decoding aprs packets

i’m not familiar with the remote control functions of the ID-5100
if it has Icom’s traditional remote control (not just ‘programming’), you’ll want a digirig pre-configured for C-IV.

the digirig ‘mobile’ can be ordered with rs-232 level, ttl level, and C-IV serial port setup.

lastly, as you’ve indicated you’re familiar with satellite work, you know you could just program in 2 memories above and below the center frequency and ‘twist the knob’ at the station.

fm capture effect, compared to working ssb birds, makes receiving pretty trivial.

good luck

Thank you for your reply.

From a teaching point of view, I have to deal with the Doppler effect to show the students the frequency excursion, which is greater in UHF. We mustn’t forget that the last ISS SSTV session was on the UHF band and that correcting the Doppler effect is essential for receiving the best possible image.

The same applies to APRS transmissions when the elevation of the ISS is not very high. However, it’s not easy to organise this kind of educational project because the ISS has to pass over the school at a time that coincides with the pupils’ timetable, i.e. the time when they have technology lessons with me.

For all these reasons, correcting the Doppler effect is essential and, as a technology teacher, I can’t see myself asking the students to change the frequencies manually when the aim of the subject is to automate the process for greater precision and optimum performance.

The icom ID5100 does have a CAT function and this radio does appear in the list of those managed by Rigctl of the Hamlib tools.

Should I conclude that with the C-IV configuration of the interface, I will be able to correct the Doppler effect while communicating in APRS mode via the ISS?

yes, C-IV configured digirig ‘mobile’ will get you a device with audio/soundcard and a serial port that is ‘wired’ for single wire communication with an icom c-iv capable radio.

good luck

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Thank you for your reply. The reason I’m here is for my educational projects, I’ve been desperately looking for the ideal radio, which for me would be an Icom IC-705 without the HF part and with 50 watts of power for a reasonable price.

Since I haven’t found one, I’m forced to consider buying a second hand Icom ID-5100, which I hope, will do the trick. It seems to be the only VHF/UHF mobile radio with 50 watts of power that incorporates the CAT function.

it is certainly a less common combination.

in 35+ years of working amateur radio satellites, i have decided i will keep using my IC-821h until it can no longer be repaired.


That’s why I’m still wondering whether this purchase is worth it and whether, despite the constraints it represents for me to have to dismantle my fixed station each time, I’m still not going to continue with my Yaesu FT-847.

Well, after a few exchanges with Denis, and because as a teacher I always try to be educational, here’s a wiring diagram to take advantage of the CAT function with the Icom ID-5100. If any of you can confirm that it works well, it would be greatly appreciated.

Thanks for sharing the graphics. Just wanted to add that this is for Digirig in CI-V configuration.

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For me it’s too late. Now that I have my answer the radio has been sold. Hope this will help other people. End of the story for me.