This video logic state is then used to mute, or un-mute, the through audio via an on-board high impedance FET switch, switch a separate output FET (controlling external PTT, Squelch Output, Relay etc.), and light an on-board status LED.
These boards can be easily hung on the back of an ATV receiver. Great for receiver such as the Comtech and saves the unwanted noise on no signal. With the increasing use of the FPV 5 GHz video receivers for ATV, the HAMKit VDAS boards make a good companion.
An on-board regulator allows DC input voltages from 5v to 16v, making this ideal for portable, mobile, repeater, home and FPV use.
A squelch tail (delay), of around 1 second holds up the SQL/PTT line during noisy signals. The timing can be easily changed through a 0805 resistor.
An additional feature of the HAMKit VDAS board is that it also has a squelch detect FET output for other uses such as repeater TX PTT, LED etc.
To use, simply feed in a composite video signal and upon correct sync being sent, then the SQL/PTT output will go low, the on board LED will light and Thru Audio enabled. Changing a solder link, the output can be inverted,if required.
Connections are taken out to the mini JST 6 pin socket and supplied cable.
4-SQL Output (LED, PTT, Relay etc)
3-Video In (parallel to the BNC input)
1-+6.5v to 16v DC In
The BNC connector can be directly exchanged for an RCA version, if required, as the design includes dual mounting holes on the board to accommodate different manufacturers, as shown below.
The board is designed to fit perfectly inside a Hammond 1551USB2TSK USB Case. All that is required on the case is a hole for the BNC or RCA connector.
- 1 x HAMKit VMAC PiHat PCB (SMT Populated)
- 1 x BNC PCB Mount
- 1 x JST mini 1mm 6 pin cable 150mm
- 1 x Hammond 1551USB2TSK USB Case
The User Guide is a dynamic document and the latest revisions, and other useful information, can found in our HAMKit Wiki pages.