Using a remote head on a uBITx for mobile operation

Dexter ZL2DEX posits that a uBitx is a bit difficult to *really* remote.  Its control and display are done by Arduino, but the unit supplied by default in the ‘kit’ has that as the ‘Raduino”, with the ‘VFO’ part of that, being the on-board SI5351. This puts RF generation at the ‘control head’, so any distance of ‘remote’ has to be minimal.

The solution, it would seem, is a homebrewed Arduino control, where the SI5351 can be controlled by the likes of its I2C-bus connection.

By this means frequency control can be a non-critical function, with distance achieved digitally: 3 wires (2 active and earth) which do not behave as transmission-lines needing such radical shielding (and can even be optically-isolated)!. This leaves Audio (By ‘dongle’?) and PTT/Keying (likewise able to be opto-isolated but also perhaps able to be encoded into the I2C bus?). Some (most?) of these modifications are already being worked on.

It’s only a short step from the above to full-USB or HDMI – or LAN/internet. Who needs megabuck rigs or even an SDR to get a remote head?

Ted K3RTA’s first attempt at establishing a uBitx with a remote head in his vehicle was with the original 20×2 LED screen. He extended the volume, tuning & function knob, and the microphone, along with the LED screen by means of a 25-wire printer cable. The Arduino/Raduino stuff remained with the mainboard in a box under the passenger seat.

The current model uses a 2.8″ Nextion LCD screen on a 4-wire shielded keyboard cable so I can see it at dashboard height. One could have run the rest of the controls to the same location.  However, the screen data nose gets hard to isolate… and Ted wanted the finger controls at a convenient arm-rest position rather than at  a reaching position.  There’s also one less microphone cable flopping around right in front of other things.  The tuning/function knob and other controls are, therefore, located in a separate control head that’s fed with a separate, VGA monitor extension cable.  The VGA cable is a Cheap-Old-Man compliant solution.  Better yet when it originated from a supply that Ted didn’t pay for in the first place. The variation and complexity of so thin a cable makes it ideal…  though an accidental discovery more so than a plan. Ted was just looking toward the shielded, 15 wires inside!

A VGA cable has four separate, shielded paths along with some extras, all shielded again by the outer layer. These can  protect the audio path.

Ted can still hear some of the Nextion activity, chiefly the data streams associated with the 2nd Nano and spectrum/s-meter action.  This is mostly on  weaker signals with the volume control turned right up.

He found the speaker audio, even with a Motorola public-safety type radio speaker,  a bit mild for 70mph highway use so Ted is adding a 15-watt amp to make it louder.

Reference

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