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Antenna Noise Bridge Low Frequency Converter 60 kHz Receiver VLF Receiver 198 kHz Converter
50 & 70 MHz Converter Audio Oscillator MSF Clock Tunable Audio Notch Filter Programmable Chime
Antenna Tuner Speech Compressor Two Tone Oscillator Sound Meter 136 kHz Crystal Calibrator

TUNABLE AUDIO NOTCH FILTER

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RARE DX under QRM ? Dig it out with this Tunable Audio Notch Filter between your receiver and extension speaker or headphones, BOOST your DX/QRM ratio, 40 dB notch, WINKLE out the WEAK DX from under tiring whistles and cw interference FAST - when interference starts just notch it out and carry on DXing. Set to 5kHz for hiss and splatter. Its built-in speaker amplifier maintains the gain and sharpens the notch so that the resulting "hole" has little effect on speech.


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TYPICAL PERFORMANCE. Notch frequency range 350 - 5000 Hz, notch depth 40dB, 20dB bandwidth 150Hz at 1kHz, unity voltage gain, input resistance 10k ohms, output resistance 1 ohm, power output 0.1W (12V, 8 ohm load), supply needed 9-15V at 50mA, controls for tuning and notch/flat (bypassed when off), 4 x 7 x13 cm, 200 g.

"heterodyne disappeared completely", Practical Wireless.
"fully compares with other makes at much greater prices", HHA in Accrington.
"impressed at the ease with which I can tune out an annoying heterodyne", Practical Wireless.
"...it works 100%", JV in Aberdeenshire.
"excellent quality and value", JD in Berkshire.

This fun-to-build kit used to include all parts, tinned drilled fibre-glass pcb, case, connectors, screws etc as well as detailed assembly and operating instructions including circuit description and diagram, and was priced at 22.20 including VAT and UK postage.
Please e-mail martincambridge@live.co.uk for the latest price reduction, details of payment and any extra parts now neeeded.

2021 April 10 David Smith We would like to help you but your email box is full