PM-SDR

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A low-cost, DDS-less  "Software Defined Radio" full coverage receiver for all HF bands, used with powerful software on the PC for multi-mode operation

 


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FILTER&SWITCH PLUG-IN BOARD for PMSDR 2.x

This is a small and compact 2-in-1 optional automatic T/R switch and tunable preselection filter plug-in board for the PMSDR. There are two filters on this board:

Main features:

Price / Availability

The tunable preselection filter have a high off-band attenuation, especially at 3th harmonic frequencies. This filter is therefore particularly suitable for the listening on the lower HF, MW and LW band.
The tuning process is done full automatically by the DLL or firmware. Therefore is possible to use the filterboard  also with the Si570-USB mode. The DLL permit also to tune this filter manually.

Furthermore, this board have also a build-in automatic T/R antenna switch, which permit to use a transceiver on the same antenna with the PMSDR (like the Switchboard): Normally the antenna is connected to the PMSDR input. When it senses RF power on RTX, the antenna is connected to RTX input. There are available three operating modes: passive, manual and automatic mode. When the PMSDR is not powered, the transceiver is connected to the antenna to avoid transceiver damage.

The Filterboard is powered from the PMSDR and doesn't require any external power supply!

The assembled Filterboard (77 x 92mm)


Passive Mode
The SDR-software disable the PTT control unit. So the antenna is always connected to the transceiver, and you can use the software to switch the antenna between the PMSDR or transceiver.  This is the same condition when the PMSDR is not powered.
Manual Mode
Use the PTT control line of your transceiver connected to the optional PTT control line input. By grounding PTT, RTX. When the transceiver is connected to the antenna, the PMSDR RX input filters are disabled for a better isolation. If PTT is open, the antenna is switched to the PMSDR RX input.
Automatic Mode

Don't use the PTT control line. When the switch plug-in board  senses RF power on RTX input (HF-VOX), it automatically switches transceiver to the antenna, otherwise the antenna is connected to the PMSDR input.

The audio output on Winrad/HDSDR can be muted automatically during the transmission. The PTT switch-off delay are software defined, therefore it's possible to change the PTT switch-off delay by the DLL  interface:

 
Tipical configuration
 
 Filterboard block diagram
 
  Tecnical data (with PMSDR):
Switch preliminary technical data:

FILTERBOARD connections overview

 



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These pages are designed and maintained by Martin Pernter, IW3AUT