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FM radio was invented to be high fidelity. All FM radio stations use pre-emphasis to boost high audio frequencies and all FM radios use complementary de-emphasis to cut high audio frequencies back to normal and cut hiss. But these extremely simple FM transmitters are missing pre-emphasis then audio heard from them on normal FM radios will sound muffled like ...


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what amplifier configuration is used in the first Picture? Certainly not common-emitter, and C2 shorts the base to ground at RF, so by a process of elimination, common-base. But what is happening in the top circuit? Which components form the resonant circuit in the top circuit? Again by a process of elimination, the resonant circuit is formed by C4, C5,...


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Concerning the radio-frequency oscillator, both circuits are the same. Components that affect frequency are the same too: C4 of circuit 1 (10pf) is equivalent to VC1 of circuit 2 C5 of circuit 1 (10pf) is equivalent to C2 (4.7pf) of circuit 2 As you have noted, the antenna goes to different places in each circuit. Both places offer a radio-frequency signal....


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In this circuit, collector-to-base capacitance would be close to \$C_{ob} \$. The base is almost grounded by C1 as far as radio frequency is concerned. \$ C_{ob} \$ is typically 2.5pf, maximum of 4pf when the DC collector-to-base voltage is 5V.(From a National Semiconductor data sheet). This measurement was done at 1MHz, not at 100MHz where this circuit is ...


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(Caveat -- I'm a toob fan-boy, but I don't have many actual tube circuits under my belt. They're just vacuum-mode FETs to me.). The final amplifier stage is screen modulated. Either someone is mistreating the EL84 in the lower right corner of the schematic, or they're being very clever and you are under-driving the transmitter. If you look at this ...


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