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AF1 

 1  

E - Z CW  

AUDIO FILTER 

 

Ramsey Electronics Model No.              AF1 

Here’s a quick and easy way to eliminate interfering CW 
signals! This filter uses a digital bandpass filter to knock out 
those unwanted signals. The adjustable center frequency and 
switchable bandwidth add some versatility to this hard working 
kit!      
 

Utilizes “state of the art” switched capacitor bandpass filter IC’s !  

Four selectable bandwidths - 750 Hz, 500 Hz, 250 Hz, and 100 Hz - 
all with digital accuracy. 

Adjustable filter center frequency for convenient listening. 

Overload protected input accepts headphone or speaker level 
audio. 

“Smart” power input allows for AC or DC operation. 

Audio bypass when unit is switched off - no need to disconnect 
unit when not in use. 

Speaker and headphone level outputs with adjustable volume. No 
need for an external audio amp.  

Summary of Contents for AF1 CW AUDIO FILTER

Page 1: ...t Utilizes state of the art switched capacitor bandpass filter IC s Four selectable bandwidths 750 Hz 500 Hz 250 Hz and 100 Hz all with digital accuracy Adjustable filter center frequency for convenie...

Page 2: ...ce Meter RAMSEY AMATEUR RADIO KITS DDF1 Doppler Direction Finder HR Series HF All Mode Receivers QRP Series HF CW Transmitters CW7 CW Keyer CPO3 Code Practice Oscillator QRP Power Amplifiers RAMSEY MI...

Page 3: ...5 Parts list 6 AF1 Assembly instructions 8 Schematic diagram 10 Parts Layout diagram 11 Hook up configurations 13 Troubleshooting 14 Ramsey kit warranty 15 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR RAMS...

Page 4: ...ter the received audio to only allow a single CW tone to be heard That s where the Ramsey AF1 filter comes in to help The audio filter board creates an audio frequency bandpass filter to remove the un...

Page 5: ...ascaded to provide sharper filter characteristics a Q LOGIC binary input to set the filter bandwidth an adjustable internal oscillator to provide the center frequency for our filter and an extra op am...

Page 6: ...8 3 100K ohm resistors brown black yellow R5 6 12 1 750K ohm resistor violet green yellow R2 1 49 9K ohm resistor yellow white white red R7 1 147K ohm resistor brown yellow violet orange R9 1 294K oh...

Page 7: ...steps First we install parts in physical relationship to each other so there s minimal chance of inserting wires into wrong holes Second whenever possible we install in an order that fits our Learn A...

Page 8: ...dphone jack Notice the seven pins protruding from the bottom of the component Be sure that none of these connecting pins have been bent over before installing J2 Solder all connections Next we ll begi...

Page 9: ...signals from the bottom to the top side of the circuit board and then back to the bottom side again 17 Grab some more scraps of leads form and install JMP2 3 4 Hey this is better than recycling if we...

Page 10: ...cement diagram 26 In the same manner install diode D2 another 1N4148 Note that the polarity of this diode is reversed 27 Install C4 1 uF disc capacitor marked 1 or 104 28 Install R8 47K ohm yellow vio...

Page 11: ...AF1 11 AF1 PARTS LAYOUT DIAGRAM...

Page 12: ...sure to orient this end as shown in the parts diagram 38 Install C1 1 uF disc capacitor marked 1 or 104 39 Install R6 100K ohm brown black yellow 40 Install C6 10 uF electrolytic Check polarity when...

Page 13: ...sure to orient the long lead as shown in the diagram The leads will slide through the holes on the top of the switch contacts Be sure to leave enough lead length on the diode so it can poke through th...

Page 14: ...commands and you did it yourself TROUBLESHOOTING INSTRUCTIONS While we had hoped that it wouldn t come to this if you re having trouble with your kit here are a few suggestions Use a methodical troub...

Page 15: ...be assured that the 1K ohm resistors are actually the missing 10 K parts Hum m m I guess the red band really does look orange Ramsey Electronics project kits are packed with pride in the USA If you b...

Page 16: ...for RAMSEY MODEL NO AF1 CW AUDIO FILTER RAMSEY ELECTRONICS INC 590 Fishers Station Drive Victor New York 14564 Phone 585 924 4560 Fax 585 924 4555 www ramseykits com REQUIRED TOOLS Soldering Iron WLC...

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