Cable for Icom IC-705 and Mobile FT8

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1

Hi there, folks!

I’m Jon KB0RB and the creator of Greyline FT8 (https://greylineft8.com) - a new iOS native app for working FT8/FT4 digital modes from your iPad or iPhone.

My app relies entirely on VOX activation circuits to work, since the iOS sandbox does not allow serial commands. As a result, I send a lot of my users (over 2,000 worldwide and growing) to Digirig in order to account for field radios that don’t support it properly. If you check out my connection guide, you’ll see I recommend the Digirig for many models of radio.

But one radio that’s been left in the cold for too long is the incredible IC-705. It’s one of the most popular, versatile radios out there, but it has a list of unique requirements as long as my arm. It doesn’t support VOX on the USB sound card line. The sound card is USB Micro B (unless you install a mod board, which many folks haven’t) and needs a special USB cable to even connect to an iOS device. It has a unique arrangement of microphone and headphone ports (3.5mm TRS and 2.5mm TRRS) that make the usual string of adapters that works for many radios impossible. And finally, because of the 8v bias voltage it sends along the lines to drive the electret mic element and powered speaker in the included speaker mic, PTT activation is very unreliable anyway.

Well, Digirig fixes all of those issues at once. I built a cable at home (with Denis’ help) that works flawlessly. With the Digirig Lite, it enables VOX-based control of the IC-705 perfectly. Even better, when paired with the DR-891 that has direct USB passthrough and Denis’ USB accessory cable, you gain full audio input/output and access to all of the 705’s USB/Serial devices. This includes full CI-V control, GPS passthrough, the USB sound card, you name it.

I’ve seen lots of folks asking for this cable over the years and am now seeking your support to get our friends at Digirig to build and sell it.

I’ve attached the schematic of the cable as well as a photo of my fairly embarrassing homemade one.

Help me make this a reality! And while you’re at it, take a look at Greyline too :grinning_face:

73 de Jon KB0RB

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2

Thanks for confirming the cable works. If there is enough interest in this kit offered in store, I’ll be happy to run a test batch.

3

Here’s one vote for producing the cable. I am a 705 and Greyline owner and would buy one as soon as it showed up in the Digirig store.

4

Another vote for making this cable available!

5

I need this cable!

6

You should make it, it’s in high demand. And Jon is a good dude.

7

Adding a vote for making this cable available.

Paul
KD3ALB