TECHNISONIC INDUSTRIES LIMITED
www.til.ca
TFM-500 Installation & Operating Instructions
TiL 98RE243 Rev. N/C Issue 12
A-5
D.
The following procedure checks for second harmonic interference to the glide slope receiver from
the TFM-500. All transceivers produce harmonics (multiples of the wanted frequency) and while
the TFM-500 far exceeds FCC requirements, interference can still be experienced depending
upon antenna position and separation. Furthermore, other equipment in the aircraft and the
structure of the aircraft can generate harmonics where dissimilar metals make contact or where
grounds are isolated, etc. This is also true of aircraft hangars; therefore, testing should be done
outside away from any structures where possible.
With a portable glide slope generator, provide enough signal to firmly activate the indicator needle
and hide all flags. Increase the signal level by 3 dB. Modulate the TFM-500 transmitter on the
following frequencies for at least 20 seconds. Observe the Glide Slope displays. Look for any
movement of flags or needles on the navigation display. If an interference condition is detected,
then the installation will have to be flight tested according to the following procedure. Using the
table below, determine the glide slope frequency based on the localizer frequency of the ILS to be
used. Divide the glide slope frequency by 2 and program into the TFM-500. Fly the aircraft to
intercept the localizer and glide slope (both needles centered) at 26 nm from the runway.
Transmit on the TFM-500 for 10 seconds and watch for any deflections or flags. Repeat the test
every 2 nm until the indicators are not affected. If the distance is greater than 18 nm, then a pass
shall be recorded. Otherwise, the TFM-500 shall be placarded “Do not transmit while on ILS
approach.”
Localizer
Glide slope
Localizer
Glide slope
108.10
334.70
110.10
334.40
108.15
334.55
110.15
334.25
108.30
334.10
110.30
335.00
108.35
333.95
110.35
334.85
108.50
329.90
110.50
329.60
108.55
329.75
110.55
329.45
108.70
330.50
110.70
330.20
108.75
330.35
110.75
330.05
108.90
329.30
110.90
330.80
108.95
329.15
110.95
330.65
109.10
331.40
111.10
331.70
109.15
331.25
111.15
331.55
109.30
332.00
111.30
332.30
109.35
331.85
111.35
332.15
109.50
332.60
111.50
332.90
109.55
332.35
111.55
332.75
109.70
333.20
111.70
333.50
109.75
333.05
111.75
333.35
109.90
333.80
111.90
331.10
109.95
333.65
111.95
330.95
