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  • Author Author: phoenixcomm
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NexGen: Component Documentation: Annunciator, SELCAL, Custom

phoenixcomm

NexGen: Component Documentation: Annunciator, SELCAL, Custom

SELCAL is a signaling method that can alert an individual aircraft that a ground station wishes to communicate with it even if the radios are muted. SELCAL signals can be transmitted over either HF or VHF RTF. A SELCAL transmission consists of a combination of four preselected audio tones which takes approximately two seconds to transmit
Below the table shows the letters and their associated frequency.

CODE FREQUENCY CODE FREQUENCY CODE FREQUENCY CODE FREQUENCY
A 312.6HZ E 473.2HZ J 716.1HZ P 1083.2HZ
B 346.7HZ F 524.8HZ K 794.3HZ Q 1202.3HZ
C 384.6HZ G 582.1HZ L 881.0HZ R 1333.5HZ
D 426.6HZ H 645.7HZ M 977.2HZ S 1479.1HZ

I had an old SELCAL unit that was in pieces, so it become my doner. I will have to make the unit's aluminum backplate 5 3/4" wide and will be .375" x 3 which is 1.125" in height. the .375" is center to center of a Dzus rail1, 2.  After which I will print the front plate with the proper clearances for the two Dzus fasteners on each side. There are 3 lights: HF Com #1, HF Com #2, and SATCOM Msg, and they will be driven by three relays. There are also 2 volume controls, Audio, and Tone. The Arduino Mega will also provide the audio tones. and the two-volume controls are potentiometers, the Arduino will give up 2 of its analog inputs for measuring the voltage of the pots.
The lamps are 23 mm x 11mm and they mount by the use of a sleeve behind the panel they were made by Ducommun part number 30288RBS1-2.
The pots were also salvaged from the unit the volume pot is 250Ω with an on-off switch, the tone pot is 10kΩ with a push switch incorporated as well. Unfortunately, I can't find the part number and there were no manufacturer marks or 5-digit cage code. The 250Ω pot has a part number of C0162080 and the 10kΩ part number is C0162081. They have date codes 9641 and 9642, which means most likely they were made in 1996 and the 41 and 42 weeks of the year. 

When I'm stumped for parts numbers or manufacturers, I use my way back machine catalog  image image

#106 from Newark Electronics. And they were not there!

footnotes: 

  1. Quarter Turn - PA-3500 Line Receptacles
  2. Panel building focussed on dimensions. “It’s all in the inch...Slight smile”