122GHz (2.4mm wavelength)

VK3CV 122GHz

Equipment for 122GHz is a VK3CV 'transverter', still to be boxed up.

Classic diode multipliers are also under construction to provide test sources.


As part of my system, I decided to implement Barry, G8AGN's Arduino TFT display design.

This provides a good visual indication of the operating mode as set by the various switches.

His original design and Sketch can be found on the 122GHz reflector.

Link to Groups.io


I decided to design a PCB to make wiring easier and also decided that I would try to make the display capable of more functions.

The result is seen below. It has become rather more complex and has been designed with as much flexibility as possible.


Prototype display front panel, V2.1 display board and schematic.

My implementation has several additional features :-

-An on-board 5V regulator, to reduce stress on the Arduino 3.3V regulator.

-Display of board supply voltage and can display a second DC voltage 0 to +30V.

-Buttons on the PCB allow you to set the VK3CV board channel.

-A simple 6 message programmable (no PC) CW Auto Keyer is implemented.

-Indication of whether the RX is above or below the LO and an output to control a switched Quadrature combiner.

-I have modified Barrys sketch to do all this and my version is pulbished with his permission.

-The board is still compatible with Barrys original Arduino sketch and then doesn't need all the extra components.

-A matching front panel / display bezel, fabricated as a PCB is also available, in 2 largeish sizes that the user must cut to fit their enclosure.

The 2 sizes are

120 x 95mm marked for Hammond 1590B (a tight squeeze), Hammond 1590T, Hammond Eddystone 29830 - 26908 PSLA

200 x 95mm, marked with all the sizes of the medium board and also big enough for EAB 2.0-200W-200D (RS Components 188-1264) extruded enclosure which is 200 x 86 x 200mm deep. see also RS 188-1265, 1266.

The 1.8" TFT Display I used was from eBay seler cayin35, item No 193545945157 The item description has full details but essentially the drive IC is ST7735S

Size is 35(W)*56 (H)*3.45+/-0.1(T)mm. The rear of the TFT display says NOMEN_TEC V2.0

-Pictures above are the 200 x 95 mm board. Markings dimensions are from drawings of the boxes. Tolerences may vary so they should be used as guidlines only

-The optional circuit on the rear of the front panel (which fits round the mounted display board) is a simple 10MHz PLL operating with a 100KHz reference

-It is similar to a number of designs for the Jupiter GPS, NEO-6M eg G3RUH. I have only done basic tests, stability may not be ideal for 122GHz.

With a good OCXO, I found the basic design usable as a reference for 10GHz SSB / CW. The board will not be supplied populated with these components


-A modified version of Pawel, SQ1GQC's Quadrature combiner, with IQ switching to allow rejection of image to be swapped from high to low is being tested.

Again modified and published original contributors permssions.

3D models of fully populated quadrature board. N.b. 'populated' PCBs I sell will not normally have the MMICs supplied or fitted.

-Documentation for my display board (jumper settings etc).

-Additional components BOM for the display board.

-Latest Modified Arduino sketchV18-12.2. Update 6/6/21

-detail of Arduino sketch functions.

-Front panel PLL Schematic (Experimental).

-Versions of Arduino IDE libraries that work! Checked with IDE 1.18.12 .13 and .15

- I will be making these PCBs available to those wishing to implement a display. Please contact me for details of PCB avaiability. eMail address on homepage

Prices, in GB pounds, excluding Post and Packing

Based on 'BULK' Purchase from PCB house

Display PCB SMD populated GBP 8.00

Display PCB unpopulated GBP 5.00

Quadrature boards populated GBP 8.00

Quadrature boards unpopulated GBP4.00

Display bezel 120 x 95mm GBP6.00

Display bezel 200 x 95mm GBP6.50


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