Modular Pre-selector for FDM-S1 and FDM-S2 SDRs and other receivers
The SPF-08 is a switchable pre-selector filter for receivers, constructed as a modular system. The device offers the base electronics to control up to eight filter boards, the filter boards can be freely selected by the user. Included in the shipment of the base system is the “pass-thru” board.
Pre-selector filters play an important role in achieving excellent large signal handling caüabilities in a receiver. Especially when living close to strong medium wave or long wave transmitters, or when using the receiver with your amateur radio station a good filter is indispensable. With the use of such filters the first stage of a receiver is relieved of strong out of band signals whoch could lead to unwanted mixing products in later stages. For SDRs the dynamic range of the ADC is much better used when unwanted strong signals are filtered before conversion.
Elad offer ready to use high and low pass filters as well as band filters for the ham radio bands. Further two empty boards are available to build your own 3- or 5-pole filters. This allows the demanding radio amateur or SWL to design filters perfectly matches to his or her requirements.
The SPF-08 Pre-Selector box offers slots for eight filters. Control is done over the 9-pin SubD socket, which is the same as used on other Elad devices (FDM-S1, FDM-S2, FDM-DUO-R). This interfaces (which is not an RS-232 interface) is provided with the frequency information which in turn can be used to select one of the eight filters. The software of the receiver provides means to adjust band edges for each filter, where switchijg should occur. After an initial setup all filter selection is fully automatic.
The case of the SPF-08 is the same as with the FDM-S2 (110 × 90 × 40 mm). Eight LEDs signal which filter is currently selected. The connection is done with SMA sockets, one SMA adaptor cable is provided so the pre-selector can be used instantly with a receiver with SMA connectors like the Elad receivers. Further an interface cable is included, which also handles the power supply. Use of this filter is in principle also possible for other receiver brands as well. For this purpose the serial interface protocol is documented, which is used by the SPF-08 to select a filter. Using an Arduino board to convert this information from another system would be a nice weekend project.
The SPF-08 pre-selector is not suitable for use with transceivers, only to be used with receivers.
The following filter boards are available:
FLP-500K: Low pass 500 kHz, attenuates everything below 500 kHz. This is the filter for the (V)LF fan and NDB chaser, but also for the radio amateur active on 137 or 472 kHz.
FHP-05: High pass 500 kHz, attenuates everything below 500 kHz, useful when you have nearby long wave transmitters
FHP17: High pass 1700 kHz, attenuates everything below 1700 kHz, useful when you have nearby long wave or medium wave transmitters
FBP-160: Band pass 160m amateur radio band
FBP-80: Band pass 80m amateur radio band
FBP-40: Band pass 40m amateur radio band
FBP-30: Band pass 30m amateur radio band
FBP-20: Band pass 20m amateur radio band
FBP-17: Band pass 17m amateur radio band
FBP-15: Band pass 15m amateur radio band
FBP-12: Band pass 12m amateur radio band
FPCB-3: Empty board 3-pole DIY filter board
FPCB-5: Empty board 5-pole DIY filter board
DAIWA CN-901-HP-3 SWR Meter CN-901HP with true peak power readout.
All Daiwa SWR meters can be selected to display average or peak power. The PEP value is found by different charge/discharge constants and therefore is not very...
ALPHA 4040 Antenna Tuner NOVEMBER TUNER UPDATE
Alpha 4040 DreamTuner
In the last 45 days, we’ve made a lot of progress on the Alpha 4040 DreamTuner. As you know, when we tested the tuner under full power, we discovered that...