Operating Guide for the King Silver Crown Radio Stack The following is a brief outline describing operations and features of the Bendix/King KMA 26/28 audio panel, KLN 94 GPS Navigator, KX 155A Nav/Com, and KT 76C transponder that most of Southwest Flight Center’s Cessna 172s are equipped with. KMA 26/28 Audio Panel The KMA 28 is pictured above. The model 26 is a slightly different, but understanding the operation of either model will enable you to operate the other without any difficulty. Most of the buttons and switches are pretty obvious from the labels depicted above. There are a couple of that need further explanation. Volume/VOX – This controls the volume and intercom VOX (squelch) for the intercom only. It has no effect on the COM volume/VOX for the radios. Push the knob in to set the intercom squelch. MONI – The connects the RECEIVE for the unselected COM to the speaker. EMG – Selecting this function by-passes the amplifier in the audio panel. It would be used in the event the audio panels amplifier failed. KX 155A NAV/COM This NAV/COM has a lot of functionality. Like the audio panel much of it can be understood by expaned labels on each switch and display. Additional information is provided below for the less obvious functions. Nav Mode – This button cycles the NAV side of the display through 5 different display modes described below. The Normal Mode shows the active NAV frequency on the left and the Standby Frequency on the right. Just like the COM side you can tune the standby frequency and use the transfer switch. The next mode (Freq/TO) is shown on the left. The active NAV frequency is on the left and the TO radial is on the right. If the signal is to weak to resolve the display will show “---“. The next mode (Freq/FROM) is shown on the left. The active NAV frequency is on the left and the FROM radial is on the right. If the signal is to weak to resolve the display will show “---“. Generally this will be the one of the most useful modes giving you a constant readout of the radial you are on without the need to change the CDI/OBS setting. The picture on the left shows the Timer Mode. The timer starts at zero when you power up the avionics. You can reset it by holding down the transfer switch for about 5 seconds. After that the timer works as a stop watch. You can start/stop the timer by pressing the transfer switch. The next mode is the CDI Mode. This mode provides an electronic CDI. You can set the OBS for this mode by pulling out the inner frequency knob and rotating it to the desired course. The TO/FROM indication is the small “v” in the center. In this picture it is indicating you are very near the 074 FROM radial. The little “V” will point upward to indicate a TO reading. When you tune a localizer frequency the radial display will show LOC. This can be a handy display mode when you have selected GPS for the Number 1 CDI NAV connecting that instrument to the KLN 94 GPS source. When the VOR signal is too weak to use this display will show the word FLAGGED under the VOR frequency. In this picture the Number 1 CDI NAV has been connected to the GPS signal. The NAV 1 VOR is set to 116.60 in the CDI mode and the OBS course is set to 225 TO. The aircraft is full scale (10o) to the right of the inbound course. NAV 2 is tuned to 114.80 and is showing that the aircraft is on the 270o radial. In all but the Normal Mode the frequency knobs will tune the active VOR/LOC frequency displayed on the left. Only the Normal Mode tunes the Standby VOR/LOC frequency. KT 76C Transponder There is only a couple of functions that need additional explanation. FL – the Flight Level in hundreds of feet is based on Pressure Altitude from the Encoding Altimeter. It will only match you True Altitude when the altimeter setting is 29.82. It also provide you with an additional visual indication that the transponder is in the ALT mode. R – This flashes when the transponder is responding to ground interrogation. ON – this setting enables the transponder to respond to ground interrogations without the Mode C (Altitude) function. ALT – This is ON with Mode C function (altitude reporting). KLN 94 GPS Navigator The operation for this is described in a separate link on this web site. You can also go to http://www.n612sp.com/KLN94UserGuide.pdf for a complete Pilot Guide.