The new SCAF-1 filter from Idiom Press makes your radio listener friendly, whether you are an SSB or CW operator. Using a modern but little known technology called SCAF filtering, the SCAF-1 is an active audio low pass filter offering user control of the filter cut-off frequency, yielding a stunning 96dB per octave roll-off of signals above the cut off frequency, and no white noise. It is the perfect partner for your crystal or mechanical filters. And, unlike most audio filters, there is absolutely NO ringing.
Why doesn’t this filter use DSP? DSP can offer brilliant results in signal processing, but good ones require significant computing power, and are expensive. They can be complex to adjust, and may require retuning any time the received signal changes frequency. Also, they can offer real problems on CW with processing delays that destroy the CW monitoring function. Unlike most DSP audio filters offered, the SCAF-1 filter passes signals through in real time, for perfect CW monitoring and QSK, and with no recovery pause on SSB when going from transmit to receive.
Once you start using SCAF-1 you will never want your rig to be without it. SCAF-1 does for your audio stages what crystal or mechanical filters do for your IF stages. SCAF-1 has two output jacks, (not switched) and will drive headphones or a speaker.
How do you use the SCAF-1? There are two controls – the in/out switch, and the low-pass cut off tuning control. By turning the single front knob, you set the audio low pass filter cut off frequency anywhere you want it from 450 Hertz to 3.5 kHz . And that’s it. Every signal or noise above the frequency you set is rolled off at 96 dB per octave. And it is done at audio frequencies – no white noise!
SCAF-1 Specifications:
Enclosure Size: 2 15/16″ wide by 1 1/2″ high by 5 1/16″ deep (matches Logikit CMOS4 Keyer)
Controls: – In/Out switch, Cut-off frequency control
Power requirement: 11.5 – 14.5 volts DC, 300 mA, through 2.5 mm coaxial power plug. The plug is included with the SCAF-1.
Audio input: RCA Phono jack
Audio Output: – 1/4″ jack and 1/8″ jack, non-switched
Amplification of inband signal: – adjustable, internal control, range exceeds minus 10 dB to +5 dB.
Low pass filter cut off frequency: variable from 450 Hertz to 3.5 kHz.
Attenuation above low pass filter cutoff: – 96 dB per octave.