Operating instructions

Operation DMH Series VHF Radio
BK RADIO Page 3-7
3.6.4 CHANNEL GUARD TRANSMIT
Monitor the channel, before transmitting on Channel Guard channels, by lifting the
microphone off hook or pressing the [MON] button. Listen to the channel for a few
seconds to ensure that no communications are occurring on the channel.
Press the PTT (Push-To-Talk) switch on the microphone. The TX annunciator
appears on the display and the red Transmit indicator illuminates while the PTT is
pressed. Talk in a normal voice with the microphone approximately one to two
inches from your mouth. Release the PTT switch to stop transmitting.
Hang up the microphone when finished. If you pressed the [MON] button to monitor
the channel, press it again after the transmission to return to Channel Guard
operation.
3.7 MIXED MODE OPERATION
The receiver and transmitter are capable of operating in analog wide-band (25 kHz
channel spacing), analog narrow-band (12.5 kHz channel spacing) and APCO
Project 25 Digital Mode.
Each channel’s Receive and Transmit Mode can be set independently as follows:
Mode RX TX
Analog Receive qualified analog
signals only
Transmit analog signals only
Digital Receive qualified digital signals
only
Transmit digital signals only
Mixed Automatically receive qualified
analog or digital signals
Transmit analog or digital signal,
depending on the status of ‘TX
Digital’ soft switch.
Digital receptions and transmissions will be indicated by illuminating the ‘ID’
annunciator in addition to the ‘RX’ or ‘TX’ annunciator.
3.7.1 MIXED MODE TALKBACK
If Mixed Mode Talkback is enabled, transmissions initiated while hold time remains
will be in the same mode as the received signal, if the signal was received on the
Ready to Transmit (RTX) channel. Depending on programming, the RTX channel
can be the main channel, a held scan or priority channel if Talkback Scan is enabled,
or the Priority 1 channel if TX on PR1 is enabled. TX Mode on the RTX channel must
be set to MIXED.
While hold time after a reception remains, transmissions will be in the same mode as
the received signal, regardless of the status of the ‘TX Digital’ soft switch. As in
Talkback Scan, the RTX channel and receive annunciators will be displayed for the
duration of the timer.
The talkback timer can be cleared by making the held channel invalid. For instance,
if a scan channel is being held, turn scan off.