TN910 Codan MT-3 and IFR COM-120 Test Procedures
MT-3 Radio Systems
TECHNICAL NOTES
TN910 Rev 5-0-0 May 14Page 6 of 16
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Distortion:
Receiver audio distortion is typically less than 3.0 %.
Sensitivity (12 dB SINAD):
Highlight DISTORTION and select SINAD. Highlight LEVEL and push enter on the keypad, then slowly turn the DATA
SCROLL spinner down to lower RF generator levels while monitoring the SINAD meter. The receiver sensitivity
point is where the RF generator level is for a 12 dB SINAD reading (The SINAD meter tends to jump around, look
for the closest RF level for an average of 12 dB SINAD). Receiver sensitivity is typically -116 dBm to -118 dBm
depending on the receiver model.
The IFR COM-120 setup as shown in Figure 4 shows a receiver with -119.0 dBm senstivity:
Figure 4: IFR COM-120 Sensitivity Test Confi guration
If the Distortion or SINAD measurements are not within Codan published specifi cations, the Front End may need
re-alignment. Refer to the Receiver Front End Alignment and Tuning section.
Squelch:
To check the receiver squelch points, adjust the RF carrier level up and down with the DATA SCROLL spinner until
the receiver squelches and unsquelches. There should be approximately 6 dBm of hysteresis (centered around the
sensitivity point) on MT-3 receivers. The squelch and unsquelch point can be adjusted on the receiver mainboard
(R88 & R115). Refer to the Instruction Manual or Technical Note for squelch setting procedures.
This product has been discontinued and is no longer manufactured by Codan Radio Communications
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