Operating instructions

Page 4 RF Technology R50
In states (c) and (d), the COS+/COS- pair can “sink” current, or not sink current, that
is sourced elsewhere.
The receivers will either toggle between states (a) and (b), or toggle between states (c)
and (d), depending on the state of the squelch.
The user can select which of these two modes they wish to use.
The default COS mode is to toggle between states (a) and (b)
2.5 COS Polarity
By default, +12V is applied to COS+ when the squelch opens, and COS- is connected
to ground,
ie the COS+/COS- pair are placed into state (a) when the squelch
opens, and are in state (b) when it is closed. (see 2.4 above).
The user can optionally select to reverse this.
Similarly,
if , the user has chosen to operate COS as a “sink” (see 2.4 above), the
default is to short COS+ to COS- when the squelch opens (state (c) above), or
open them when the squelch closes. The user can reverse this as well.
2.6 Noise Blanker
The R50 has a noise blanker. This circuit detects RF impulses and quenches the RF
before it is de-modulated. This prevents “clicks” and “pops” from being
detected and passed through to the audio. The noise blanker can be enabled or
disabled by the user.
2.7 Advanced Slot Selectable Parameters
WinTekHelp receivers have several advanced features. These features can be
programmed for each channel.
One of these advanced features is to program up to 8 frequencies on a channel. When
this is done, we refer to the “channel” as a “slot” to avoid confusion, as many
people equate the word “channel” with the word “frequency”.
When more than one frequency is assigned to a “slot”, and that slot has been selected
from the channel input, the receiver will automatically scan all the assigned
frequencies, tuning to the first that has sufficient carrier strength and/or
SINAD, and a correct CTCSS tone, or correct DCS code.
In this “scanning” mode, one of the frequencies can be given “priority”. If this is
done, the receiver will check, every few seconds, if there is a signal on the
priority frequency, and if so, it will switch to the priority frequency. It will
stay tuned to the priority signal, whilst signal is present on it, but it will then
resume its usual scanning function, if the signal is lost.
Another advanced feature is the ability to assign more than one CTCSS tone to a
frequency. When this is enabled, the receiver checks if the received CTCSS
tone is one of up to 6 tones rather than just one.
Another advanced feature is to inhibit the assertion of COS, or loop, (or both) when
the squelch opens depending on either the frequency received or the tone
detected.
For example, in a scanning situation, with two possible frequencies, LOOP can be
programmed to be asserted if one frequency is detected, or
COS to be asserted