What is it?

This product is developed for building classical HF-relay stations, that work with an entry- and exit-channel. It allows an interconnection between the entry- and exit-station with an UHF/VHF radio-link, rather than with a cable. Which gives one great freedom in regard to where to position the relay station.

The best practice is to use two Stheleris VP2MKs and use them as unidirectionial cross-band-repeaters: HF to UHF/VHF and UHF/VHF to HF. The high-precision VOX function of the VP2MK allows to setup the forwarding of the signal, from entry to exit, in very precise way. The analyzer of the VP2MK is that sensitive, that it can detect a radio's closed or open squelch, even when the volume is muted. This leads to a nearly instant forwarding of the signal with almost no "VOX-tail" at its end. Furthermore the VP2MK includes a LF-adjustment to match the radios output signal to the respective input. This leads to a clean and undistorted forwareded signal with almost no loss of its quality.

In- and outputs

The Stheleris VP2MK offers one LF-input, for analyzing and forwarding the incomming signal, and three LF-outputs, where one of them provides the adjusted signal and PTT-trigger for the Midland-standard and the other two provide seperately the adjusted signal and PTT-trigger for the Kenwood-standard. This way one can connect any desired radio devices, that have headset-sockets either in the Midland- or Kenwood-Standard, like the most handheld transceivers of those companies have. In case one want to connect radio devices with no such headset-sockets, one still have two possibilities: One can either use the additional digital output of the VP2MK to switch a further ralay (not included) or one can use the Kenwood PTT-trigger and easily adapt it to the radio's needs.

Firmware configuration

The configuration of the Stheleris VP2MK can be done in real-time by connecting a PC to its serial interface (UART). There you get a standard terminal to log in and can configure the firmware according to your needs. There are 20 parameters you can adjust, from VOX-threshold and tail to hystersis and TOT. You probably won't find any other VOX with such precise settings. The dynamic range of the VOX-threshold is -90dBFS in 32768 steps. The analyzing speed can be set down to 0,83ms. The analyzing LF-band can be set from 4000 to 24000Hz with a depth of 16bit.

Pre-configured for Midland/Kenwwod radios

The VP2MK comes ready-to-use and pre-configured with a default setting, which should fit most radios with Midland/Kenwood headset-socket. We tested the configuration with the following radio devices: Midland Alan 42 DS, PNI Escort HP 62, Midland XT50, Midland XT50 Pro, Midland XT60, Midland XT70, Baofeng UV-5R, President Randy III, President Randy III Pro, PNI Escort HP 82. But of course one can also realize radio relay stations e.g. for the the 10m band. (Be advised that a radio relay more or less requires FM modulation.)

Further reading

Below under 'Documentation' you can find the manual for the VP2MK. Instruction how to set up a relay station can be found here: https://stheleris.com/vp2mk/manual_relais_latest.pdf

More information can also be found here: https://stheleris.com/vp2mk/

What's in the package?

You get 1x Stheleris VP2MK high-precision VOX-control, 3x Sonero double-shielded LF-cable 50cm (2 of them with sheath current filter), 2x 3,5 - 2,5mm audio jack adapter. The necessary 5VDC current supply for the VP2MK is NOT included! You can use e.g. customary powerbanks with a cable with a USB micro B connector for this purpose.