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

8

IC705 really is incredible. If votes are needed to determine whether this cable is picked up and made, count me in!

So many people use the 705, beginners to hacke…er… Experienced hams. Thanks Jon and Digi Rig for your contributions to the ham space!

9

Here is another vote.

I’ll buy one as soon as its available.

10

Thanks everyone for the support! I think we just might make this happen.

Wanted to leave a quick update that I spent the last week using my homemade cable with my 705 and it’s been working great.

Tuesday:

  • 15 QRP FT8 QSOs via Greyline on iPhone

Wednesday

  • 5 Greyline FT8 QSOs on iPhone
  • Winlink Wednesday via RadioMail on iPhone
  • VarAC Wednesday check in (and a couple of random chats), using a Windows PC but routed through the DR-891 via the custom cable
  • 2 APRSOTA operations via RadioMessenger on iPhone

Thursday

  • #APRSThursday net via RadioMessenger on iPhone
  • 2 APRSOTA ops via RadioMessenger on iPhone

Everything worked flawlessly. It’s really opened up a whole world of new possibilities for the 705! I hope everyone does buy these cables when they become available so they can be a regular stock item.

11

I would like to add my support for this new cable. I have Greyline FT8 running on my iPad with Digirig Lite and the Digirig cable for Icom IC-706 running on my IC-7300 (OG). It works great. I am planning on getting a 705 soon and a cable for it to work with Digirig lite would be my first accessory purchased. 73’s, Andrew VK2AWN.

PS: Here’s my post on using Digirig Lite, the 706 cable and Greyline FT8.

12

just wondering why audio out from digirig to speaker out 705 and audio in digirig to mic in 705 wired? Or am I missing something

13

it’s the iphone/ipad that is missing something.

a way to key up the radio.

iphone/ipad won’t let you ‘use’ a serial port over usb so the only way to key up the radio is vox.
digirig lite has a nice clean vox solution alongside the usb audio device.

(i’m an android kinda guy thankfully)

:slight_smile:
kb0wlf

14

Good catch, but the pin diagram is right. The labeling is from the radio’s point of view and the DigiRig handles the rest. On radios that support the direct audio/VOX method like the KX2, you do have to cross-connect the mic to speaker and vice-versa. In this case we’re just noting which connector goes where and the DigiRig deals with the audio path.

15

I have an IC-705 and would prefer to buy a cable made by DidiRig rather than make one myself.

16

I’ll buy two cables for IC705

Thanks

73, AA1SL

17

HI, would love to use Digirig with my I-705, it would be great if Digirig could/would build an interface cable.

Thanks!

18

I would buy one, thanks!

N8FRJ