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OHIS/HHI Test Recordings

Insert obligatory “It’s been too long since I’ve posted!” apology, and “I’ll be sure to post more often” empty promise here. Now that that’s out of the way…

If you just want to listen to the HHI recordings, skip to “Without further ado…” at the bottom of this post.

What happened to SOAR?

I just realized I haven’t posted here about putting SOAR on hold. See above; I haven’t been good about posting here, but I HAVE been good about posting to the Groups.IO lists. I suggest you subscribe to that if you want to stay up-to-date. 😉

The short version of a very long story is: I was never able to make the SA868 UHF module work sufficiently with the band-pass filter that SOAR requires. I’ve had several people look at it, and the consensus is: We’re doing the right things, but its not working right.

In the interest of pulling in an income and not just living off savings forever, I’ve put SOAR on hold and switched to working on the Open Headset Interconnect Standard, or OHIS.

The tl,dr is: It’s an open standard that defines both an electrical and physical standard between the radio and the user. The goal is for any user to be able to take any headset to any radio, without needing an adapter that is specific to the pairing of that headset and radio. This is especially useful in a multi-user environment, like a club shack, an EOC, or a contest station.

For more about OHIS, see

What is HHI?

OHIS is an Open standard, but the designs of hardware that implement that standard don’t have to be. The Halibut Headset Interconnect product line, or HHI, from Halibut Electronics implement the OHIS standard, and add more features. They are commercial products.

The first two products are:

HHI Radio Pro

Adapts an OHIS Radio port to nearly any radio. Also provides “Passthru” connections that allow the radio’s stock devices (microphone, speaker, headphones, PTT, etc) to still be usable too.

HHI User Pro

Adapts nearly any headset to an OHIS User port. Also provides a simple two LED VU meter to aid mic level setting.

You said something about recordings?

I did! I’ve got working prototypes for the HHI Radio Pro, and working-after-a-simple-modification prototype of the HHI User Pro. It’s enough to setup my home station to be fully OHIS compliant, which it is now! Yay!

Recording setup:

My two radios are a Flex 6400, and a Kenwood TM-D700. Both radios are transmitting low-ish power into a dummy load for these tests.

The four sources of audio are:

The receiver is an RTL based SDR on my laptop (an older version of the NooELEC) , running GQRX.

Disclaimers: The RTL is old, and not very stable. You’ll hear it drift around while listening to SSB on the Flex6400 recordings. Also, GQRX was digitally clipping the FM received audio, I can’t figure out how to stop it from doing that. It doesn’t happen on the audio sent to the sound card when listening live, nor does it happen when listening on other receivers. The clipping is in the recording, not in the OHIS hardware.

Without further ado…

Here’s the Flex 6400 recording.

HHI Test Recordings, Flex 6400

And the Kenwood TM-D700 recording.

HHI Test Recordings, Kenwood TM-D700

Shut up and take my money

I’m not quite there yet, but will be very soon. I’ve got one more HHI User Pro prototype on its way to verify the changes and additions I’m making to it, but the HHI Radio Pro is good and solid. My HOPE is to be selling these by May 2023. Make sure you’re subscribed to my HHI specific sub-list at to hear status updates before anyone else.

As always, let me know if you have any questions, comments, purchase orders, etc.

Cheers, and 73 de N6MTS!

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