The PTT-24 is a Push-to-Talk lockout device. It is used with multiple E&M circuits linked to radios. The PTT-24 solves the problem of radio transmitters being locked into a Transmit ON state when a T1 circuit fails. Many T1 trunk lines will go into a busy condition when the T1 trunk fails. This causes the E&M leads to lock in an ON state, which causes radio transmitters to lock in the ON state.
The 12 or 24 E&M ports are wired through the PTT Lockout unit. A front panel toggle switch is used to select 12 or 24 port operation. A 2 position push button switch is used to select the control port. The Power LED flashes if an invalid control port number is selected.
Based on the selected control port (via the front panel) the PTT Lockout device will detect a closure to ground on that port and de-assert all the other ports. Supports E&M Type I, II, IV, and V, E&M Type III is not supported.
In the PTT-24 12 port mode, selecting control channel 1 through 12 will select one of the even numbered leads 26 though 48 as the control port. The other 11 even numbered leads will be de-asserted if the control port is asserted. All other leads are passed straight through.
In the PTT-24 24 port mode, selecting control channel 1 through 24 will select one of the leads 26 though 48 as the control port. The other 23 leads will be de-asserted if the control port is asserted. All other leads are passed straight through.
If the PTT-24 were to lose power, the E-leads will be in a pass through mode as though the PTT-24 is only a “lump in the cable”.
Lockout can be triggered by the E&M control port being activated or the alarm input. For both the control port and the alarm input, there is a delay of 20 milliseconds before the lockout occurs. The de-activation delay is 5 seconds. The de-activation delay eliminates lockout “chattering” on/off/on/off, etc.
Leads 1 though 25 and 50 of the 50 pin Amphenol Telco connector are passed straight through.
SPECIFICATIONS
General
Front Panel (these are approximate placements, subject to relocation)
Toggle switch to select 12 or 24 E&M ports
Push button switch to select port 1 to 24 for PTT Lockout control
Test switch, momentary, to test lockout function
Front panel switch to kill an audio alarm that will sound when/if the control port activates
Green Power LED (flashes if an invalid control port number is selected, i.e. 00, 25, etc.)
Red "ALARM" LED to indicate the PTT Lockout switch is activated
Yellow "ACO" LED to indicate the ALARM CUT OFF is on
Rear Panel:
2 power inputs for -48 VDC power, diode protected between the 2 power inputs to avoid power feed back
Alarm Input (dry contact closure) to externally activate the PTT Lockout function and/or test the unit
Alarm output dry contact
Female 50 pin telco connector from the channel bank, screw connection and cable tie type
Male 50 pin telco from the PTT lockout to Transmitter side of the circuit, screw connection and cable tie type
Physical/Electrical
Stand alone or 1U high rack mounting
Power requirements: -48VDC
19" W x 10" D x 1 3/4" H
Three pounds
Environmental
Operational Temperature: -40 to +70 C
Storage Temperature: -50 to +75 C
Humidity: < 95% Non-condensing
This is a limited volume production product. Please contact your sales representative or phone 800-432-2638 to determine lead time and pricing. Typical lead time is two to four months after receipt of order.
Data Comm for
Business Inc.
2949 County Road 1000 E
Dewey, Il 61840
