In a previous post (Hermes Lite 2, Winlink and Vara), I published two paths for improving how Vara HF Modem works with the Hermes Lite and Thetis Software. This post is the specifics of how I connected the DigiRig-Mobile in particular, but this method could be used with any other “sound card” such as a RigBlaster or SignalLink.
This modification depends on the existence of the Hermes Lite 2 Plus adapter. This slick adapter puts a CODEC directly into the HL2 allowing microphone and headphones to connect to the data stream in parallel with Thetis software, but bypasses the virtual audio cables. This is a real boon for CW operators in particular because the delays in the audio chain makes a pretty big mess when it comes to sidetone making paddle-keying difficult. This adapter (and the updated gateware that goes with it), also puts a full iambic keyer on board the HL2+. Just add paddles.
Modifications
Because the microphone, headphones, and PTT signals are readily available on the add on board, connecting the external sound card is pretty simple. The DigiRig Audio connection is all that is needed (the green, Serial-Rig-Control connection can be ignored). This is a TRRS 3.5mm jack wired as follows:
The header on the HL2+ Adapter is wired like this:
I carefully added a hole to the HL2+ faceplate as shown below. This placement clears the HL2+ adapter’s jacks and keeps the wires short.
The connector was then added with the following pin assignments:
- J3-1 (Tip) Speaker (Headphone Right)
- J3-5 (R1) MIC
- J3-4 (R2) PTT
- J3-3 (Sleeve, K) GND
The result is that a 3.5mm TRRS cable can plug directly into the front of the HL2+ from the DigiRig-Mobile Audio Jack.
Operation
When using this configuration with WinLink, VaraC, or any other digital-mode application, I set Thetis to upper-sideband (USB not DIGU), the MIC button in Thetis is then enabled and the gain is set to about -4dB. Your results may vary.
As mentioned in the previous post, this modification is not required to get Vara HF to work, but it is a clean setup that eliminates the VAC (virtual audio cable) and I have had very solid connections with good data rates using this method.
Hope this helps!
Peace and 73,
WR9R
