The in ner marker is lo cated close to the end of the run way. The
bea con trans mit ter and an tenna are de signed to pro ject a cone
shaped pat tern of 75MHz en ergy, ver ti cally. The ra dio fre quency
out put of the trans mit ter is mod u lated with an au dio tone of
3000Hz. An air craft equipped with the KR 21 will re ceive a
3000Hz tone in head phone or speaker and the white lamp will be
il lu mi nated while over the sta tion. The in ner marker is used to in -
di cate a point ap prox i mately 1500 ft. from the run way and if on
proper glide path the al ti tude above the run way should be ap prox i -
mately 100 feet.
The Hi-Lo Switch in the KR 21 pro vides sen si tiv ity switch ing ef -
fect of the high sen si tiv ity po si tion is to greatly en large the size of
the cone shaped “ area of in di ca tion” above the sta tion. An air craft
fly ing at high al ti tude or slightly off course may fail to re ceive the
sig nal when in the low sen si tiv ity po si tion. It is sug gested that the
KR 21 marker sen si tiv ity switch first be placed in high sen si tiv ity
po si tion un til au ral and/or lamp in di ca tion is re ceived. The con trol
switch may be turned to low sen si tiv ity to re duce the du ra tion of
the in di ca tion and to ob tain a more ac cu rate read ing of pas sage
since the sig nal ap pears to build and fade faster on low sen si tiv ity.
The high sen si tiv ity po si tion may be used to ef fec tively give the
pi lot an ad vance in di ca tion that he is ap proach ing the outer
marker. In or der to ex pe dite the ILS ap proach the pi lot may wish
to re tain higher speed un til he is nearby the outer marker in bound.
With the KR 21 marker in high sen si tiv ity po si tion the au ral tone
will be gin about one mile from the outer marker. At this time, the
pi lot may switch the KR 21 marker to low sen si tiv ity and re duce
en gine power for fi nal ap proach speed, also retrim and per form
cock pit checks. He is then pre pared to be gin de scent when the
marker in di cates ac tual pas sage over the outer marker and the
glideslope is in ter cepted.
KR 21 MARKER BEACON
SCHWEIZER MODEL 269C-1 HELICOPTER
CSP-C1-1A
FAA Approved: 03 Oct 1995
29
Revsied: 17 Apr 1996
