Custom Products from Masters Communications

What is it, and why do I need it?

Some RF amplifiers require a keying logic to be asserted prior to RF drive arriving. This PTT Sequencer provides an adjustable time delay to insure the RF amplifier has been enabled (keyed) prior to RF drive arriving. This allows changeover relays to be switched absent RF power to keep the contacts from arcing and accidentally tripping the VSWR protection circuitry.

This unit requires a source of 12VDC power and an optional wall type power supply is available separately.

This optional power supply can used to power the audio amplifiers in the RA board from a mechanical header / jumper - no soldering required.

Simple description:
Simply install the PTT Sequencer in the line between the radio interface and repeater or transmitter to provide the necessary time delay. The unit is built with a "straight-through" connection scheme keeping the pinout of the "RADIO" port the same as the RA interface with the exception of the additional (non delayed) amplifier PTT output that now appears on DB9 pin 9. The "FROM RA" DB9 female connector mirrors the RA board pinout so a 1:1 cable is used to connect it to the sequencer. Pin 5 of the "RADIO" connector is the normal PTT which is delayed going to the radio / repeater.

Detailed description and operation:
Each PTT output is sourced by its own reed relay, capable of 1A of current. The timing circuity is similar to what's used in the W6PQL sequencer and the delay time is adjustable over a pretty wide range. It requires a clean source of 12VDC and operates from your own power supply or a wall wart (available separately). There's even an option to power the audio amplifiers in the RA board from this external power source - required by some radios / repeaters. The PTT logic is not delayed going to the amplifier output on DB9 pin 9. The radio / repeater PTT is delayed by the amount dialed in by the potentiometer R3 - delay time.

Features:

• The sequencer easily connects between the RA and repeater (TX radio) with straight through DB9M to DB9M cable (not included).
• Very easy to build - not many components - also available built and tested.
• Metal SC Case for durability - available in black, blue, or red.
• PTT LEDs for easy viewing of PTT status.
• Kit comes with all required components, connectors, metal case, end panels and screws.
• Adjustable delay from 0 to 100mS.
• Two Reed Relays for optimum compatibility and reliability.
• Header/Jumper (JU1) to allow 12V to be routed to the RA Board audio amplifiers (when necessary).
• Optional 12VDC power supply available separately.
• Optional Power Pigtail available separately (to use you own power supply).
• Available assembled and tested, as shown in the photos above, for additional fee.

Secure Online Ordering - Use down arrow to make selection.
Quantity can be changed after pressing the "Add to Cart" button.
Shipping amount is calculated at checkout for shipping to most locations Worldwide.

Shipping amount is calculated at checkout for shipping to most locations Worldwide.

Email Kevin Custer for ordering information, ordering by check, and/or support of this exciting product.

Product of Masters Communications, all rights reserved.
Designed by Kevin Custer W3KKC
Specifications may change without notice.
Images are property of Kevin Custer - W3KKC
Board layout by Kevin Custer W3KKC
HTML 3/15/2026, Kevin Custer All Rights Reserved!