The best speaker to use with this audio amplifier is a 4 ohm, 8 watt, 4" to 6" size speaker. A small one comes with some of the kits, but it does not give the best audio compared to using a larger speaker.
Some of the kits may contain a LM383, but it is identical to the TDA2002. Same pin out and electrical characteristics.
Most ham CW and SSB communication is between 300 Hz to 3000 Hz. The following is a chart reprinted from the SGS data sheet intended to aid the designer for fine tuning the audio amplifier.
|Part||Value||Purpose||Larger Value||Smaller Value|
|C21||2.2 mfd||Input DC decoupling||Noise at switch-on, switch-off|
|C22||470 mfd||Ripple rejection||Degradation of SVR|
|C25||0.1 mfd||Supply bypassing||Danger of oscillation|
|C24||1000 mfd||Output coupling to load||Higher low frequency cutoff|
|C26||0.1 mfd||Frequency stability||Danger of oscillation at high frequencies with inductive loads|
|C23||39 pf||Upper frequency cutoff||Lower bandwidth||Larger bandwidth|
|R7||220 ohm||Setting of gain||Increase of drain current|
|R8||2.2 ohm||Setting of gain and SVR||Degradation of SVR|
|R9||1 ohm||Frequency stability||Danger of oscillation at high frequencies with inductive loads|
|R6||39 ohm||Upper frequency cutoff||Poor high frequency attenuation||Danger of oscillation|
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Beginner and Experimenter's Receiver Kit
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