COMMS / NAV panel for 737NG

The design Ver 0.0 is based on a big picture of the cockpit, I have with measurements on this side.


The NAV and COMMS panel are similar size. Placement of the knobs and displays is slightly different, but not a lot. If they were the same it would not show even for the purists.

That is why I make one single PCB that I can use for both panels.


  1. The TFR on the Radio Panel is a toggle switch, that is set to the direction of the active frequency. On the NAV Panel this is a push button. On the universal PCB we would just glue the tact on top PCB, and hand wire it.
  2. On the Radio Panel on the left, there is a double encoder with switch, while on the NAV Panel there is a button (TEST). On the PCB I made soldering pads for one or the other.
  3. The NAV Panel will not have IC4 installed. A bridge wire has to be soldered between 10 and 9 of that chip and a wire has to be soldered to connect this button to IC3.
  4. The Radio Panel (COMMS) panel has 2 LED’s indication active frequency. The NAV has not, simply do not mount.

Prosim and PMDG Radio and Nav panels:

2017-12-06 14_42_33-ProSim737 Panel


2017-12-06 14_46_08-Microsoft Flight Simulator X








In Prosim, both pannels are exacly the same layout and functions. While in PMDG the Comms panel is more complex, with a sub-panel for further selections.


On the picture above frequency displays have 5 digits [118.00].

I also have seen panels where the COMMS Radio frequency is 6 digits. Especially COMMS frequencies in use in the real world have 3 decimals [108.000]. I designed the panel with the option to install the 3rd decimal digit.

If you do not want to use this 3rd decimal digit, do not install either the first or last digit of the set. A decimal point is wired in 2 places [0 0 0. 0. 0 0], so either the last or first digit can be left out: [ X 0 0 0. 0 0] or [0 0 0. 0 0 X]. The decimal point needs to be set by the script.

Rotary encoders

I use double shaft rotary encoders with push-switch. Dual shaft is like the real thing. The push action can be used to toggle the 3rd decimal XXX.XX0 or XXX.XX5.

Size of the PCB

The size of the actual PCB is smaller than the size of the front. I foresee 3 mounting holes near places where pressure from knobs or buttons is applied.


Schematic - D__eagle_FSIO COMMS-NAV_737COMMS.sch

If you have read the explanation about panel hardware, you will see that there is not a lot of difference here – 2 input chips and 2 display chips.

In the hardware section of the downloads I put the Eagle files for the PCB.

The PCB allows to be build in Prosim configuration and a configuration with 2 double shaft encoders. You can use a middle or left Test button. You can choose to mount 5 or 6 digits for the frequency’s displays.

To build for PMDG, one should mount a single shaft encoder at the left position (SENSE). The non-used inputs can be handwired to the sub panel. In a next version of this PCB I will try to include the OFF and Test buttons and a socket for the sub panel. This PCB can be used, if unused inputs are handwired to the subpanel on top.

I have build and tested the board with Pro-Sum configuration. (minor mistake is the digit numbering D0 <> D8, D1<>D9 etc.

2017-11-19 16_36_02-webGerber


2017-11-19 16_37_47-webGerber


Note that the IC’s and the connectors are mounted at the back side of the PCB. The capacitors, displays etc. on the front.

The dotted line gives the wire that needs to be installed to allow the Test button for the NAV panel when IC4 is not installed.


I created a eagle lib element for the rotary encodes with dual shaft. I used a ELMA type 27 library to just add the extra 3 pins.

If you look at the eagle files, the measurement lines in green are the outline of the front panel.


The PCB’s are available at: My first Boeing Shop