RUNRACE : Service & Maintenance Manual - rev. 2.0
Page 11.4
Sensitivity is reduced by soldering a resistor in parallel with the coil. Normally, the receiver already
has a 15 KOhm resistor mounted in parallel with the coil, however it is advisable to check for its
presence.
The following table shows the nominal values of reception distance based on the value of the
resistor soldered on the coil:
RESISTANCE
(Ohm)
DISTANCE
(cm)
15K 89
13K 88
11K 87
9K1 85
6K8 84
5K1 81
3K 74
2K 69
1K 57
Please note that these are only nominal values. The actual reduction in sensitivity must be verified
experimentally, taking great care not to excessively reduce the reception distance.
WARNING: if there is already a 15 KOhm resistor mounted in parallel with the coil,
note that adding another resistor in parallel will produce a total resistance value
equivalent to the parallel combination of the added resistor and the existing 15 KOhm
resistor.
11.1.4. MECHANICAL VIBRATIONS
Mechanical vibrations may cause slight shifting of the coil, giving rise to transient impulses. If these
transients occur only occasionally they can be easily filtered by SW. However, if the mechanical
vibrations are periodic, they can produce periodic pulses which may be interpreted as correct heart
rate values.
To eliminate or reduce the effects of vibration, house the receiver between the foam pads in such a
way that any vibrations are correctly damped.
WARNING: when securing the foam pads and the receiver with a strap, be careful not
to overtighten the strap as this may reduce the damping capacity of the foam pad.
11.1.5. POSITION OF THE RECEIVER
Carefully position the receiver according to the specifications below:
• the coil must be directed toward the user;
• the coil must be positioned well away (even a few centimeters) from the LEDs;
• the cable must be folded immediately after the connection on the receiver, so that it does not
pass near the coil;
