Ramsey Electronics HR20 manual

Page 24

The ‘-’ side of the new capacitor is connected to the circuit trace leading to the volume control. Mount this capacitor as close to the body of the new LM386 as possible. Keep all leads as short as possible. This modification results in very good speaker volume but will also require closer attention to battery quality and condition or else the audio circuits will cause oscillator instability. Two alkaline cells in parallel or a 12 volt supply are recommended. If the gain is too much, use a resistor to reduce the voltage supplied to pin 6 of preamp LM386

Finally, we remind you again that modification of any PC board puts you on your own, voiding your factory warranty, making your unit ineligible for factory repair. Make sure the receiver is working properly and that you understand how to use and repair it BEFORE making any changes in the original design. Enjoy it!

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Contents ALL Mode Receiver KIT Partial List of Available Kits Ramsey Transmitter Kits HR20 Amateur Receiver KIT Introduction Ramsey HR-SERIES Amateur ReceiversAbout Direct Conversion Receivers Circuit Description Capacitors Parts Supplied with the HR20 KITLEARN-AS-YOU-BUILD Receiver Assembly Strategy HR20 HR20 Parts Layout Diagram Receiver Assembly HR20 HR20 Initial Testing of Your HR20 Required for Initial Testing and AlignmentAlignment Alignment Hint for ALL Direct Conversion ReceiversUsing Your Receiver Tuning SSB SignalsCW Operation On the AIR TRANS-RECEIVINGSpeaker Operation More Audio Power Another WAY Adding AN LED Power on IndicatorTroubleshooting Tips Alternate Power Sources General Notes for Experienced QRP BuildersBandspread and Tuning Range Frequency Stability Other Methods of Dial CalibrationDirect Frequency Readout LM386 Audio Output HR20 Construction Notes Ramsey Kit Warranty Factory Repair of Assembled Kits Total Solder Points Estimated Assembly Time HR20 Amateur Receiver KITRequired Tools Additional Suggested Items