mcHF Connections - df8oe/UHSDR GitHub Wiki

mcHF Connection Panels

Right Panel

• Line In/Out (Line IN/Line OUT)

  Used for External device audio input and output. Not affected by Audio Gain setting.

• Microphone/PTT (MIC)

  Used for Microphone audio input and Push-To-Talk switching.

• Speaker/Phones (PHONES)

  Used for Headphones or External speaker. Level is controlled with Audio Gain setting. Auto-disconnects Internal speaker when a connector is inserted.

  Be careful when wearing Headphones. Audio Gain setting has to be properly adjusted to avoid damage to your ears!

• Power Connector (DC IN)

  Used for providing 9-15 VDC (center positive) to the mcHF. Internally has a 3A SMD fuse to protect from overcurrent.

• Paddle/Key (KEY)

  Used for suitable telegraphy key or paddles. Configured by menu entry.

• Accessory (ACC)

  Used for triggering Push-To-Talk in External linear amplifiers or other devices.

Left Panel

• USB-A (HOST)

  Used for loading Firmware updates into the mcHF. "USB-A" type.

• mini-USB (DFU)

  Used for Rig control (CAT: TS-817) and Digital audio in/out (48 kHz). "Mini-B" type.

• Antenna Connector (ANT)

  Used for 50Ω antenna network or known-good dummy load. RF in/out - "BNC" type.

mcHF Connector Details

Power Connector (DC IN)

For fixed station use, a low-noise 12-14 VDC power supply is recommended. Any suitable 12V nominal battery is recommended for portable station use.

Maximum power output varies with input voltage.

Recommended voltage for full output power is 11-13.8 VDC.

DC IN (J1-RF) is a female coaxial power connector to supply DC power to the transceiver. The center is positive (+) and the outer shell is negative (-).

• Technical data: IEC 60130-10:1971; Type A: 5.5 mm OD, 2.1 mm ID

• Specific data for mcHF:

  • Maximum voltage: 15 V
  • Minimum voltage for full transmit power: 11.0 V
  • Min. voltage for reduced transmit power: 9.5 V
  • Min. voltage for receive-only: 6.5 V

DC Connector pinouts

Paddles/Key (KEY)

The 3.5 mm TRS KEY jack connects to telegraphy (morse) equipment. Connect a set of paddles or a straight key to the transceiver, depending on the "CW Keyer Mode" menu configuration setting.

KEY pinout

Straight key wiring

Simply consists of a N.O. (Normally Open) switch between Ground and Dah pins. Only two wires are needed.

Paddles wiring

Consists of two N.O. switches sharing a common Ground pin. Three wires are needed. The "CW Paddle Reverse" menu option settings reverses the sense of the Dit and Dah pins.

Accessory (ACC)

The 3.5 mm TRS (Tip-Ring-Sleeve) ACC jack is used to control the transceiver and make the Push-to-Talk (PTT) signal available for external devices. Grounding the Tip pin keys the transceiver (puts the mcHF in transmit mode). The transceiver grounds the Ring pin when keyed - typically used for keying an external amplifier. The Tip pin can be considered "PTT In", and the Ring pin "PTT Out".

ACC pinout

External Amplifier wiring

This example will show how to connect the keying control line to a KXPA100 external linear amplifier.

To avoid damage to the transceiver and/or external device, double-check the control line "sink current" is a typical 100 mA or less, and grounding the control line activates transmit mode. You must ensure the control voltages and currents and the control signal sense are compatible.

Line In/Out (Line IN/Line OUT)

Line IN is a Stereo audio input jack, selected by the "Mic/Line Select" menu option or M3 (long press). The level is adjusted by the "Line Input Gain" menu option or ENC3 in TX Mode.

Line OUT is a Mono audio output jack, with L and R internally connected. The level is adjusted by the "Lineout Gain" menu option and is unaffected by the transceiver's "AF Gain" (AFG) setting.

Line IN/OUT pinouts

Line IN/OUT wiring

Any standard 3.5 mm TRS plug stereo audio cable is suitable.

Microphone/PTT (MIC)

The MIC TRS jack is used for both Mic Input and a PTT switch. This input is selected by the "Mic/Line Select" menu option or M3 (long press). The level is adjusted by the "Mic Input Gain" menu option or ENC3 in TX mode. A dynamic or electric mic type is selected by the "Mic Type" menu configuration setting.

The transceiver switch-over when activating PTT produces a "thump" (or "clunk"), particularly with electret mics. In most cases, the "TX Initial Muting Time" default of 10 ms in the configuration menu is sufficient.

MIC pinout

Microphone/PTT wiring

Speaker/Phones (PHONES)

The PHONES jack is used to connect headphones or external speakers. Gain is adjusted by the "AF Gain" (AFG) control ENC1. The transceiver internal speaker disconnects when a plug is inserted.

Be careful when wearing headphones. Volume control (AFG) should be adjusted downward to avoid damage to your ears!

PHONES pinout

Speaker/Headphones wiring

USB Ports (HOST and DFU)

The USB-A HOST jack is used to connect a computer keyboard (PSK and RTTY modes) or for loading firmware from a pendrive.

for compatibility, it is recommended the pendrive does not exceed 16 GB capacity.

The mini-B DFU jack is used for digital audio I/O (usb audio) and mcHF Remote Control (CAT FT-817 protocol). Refer to USB CAT and AUDIO Mode for further information.

Antenna connector (ANT)

The BNC ANT jack is used for RF input and output.


(outer shell is ground)