04-12-2008, 08:52 AM
>>slightly off-frequency results in better high frequency response (why is that?
You're peaking the radio's passband on one of the transmitted sidebands, and off the other. Both sidebands carry the same signal, so you can afford to lose one.
A lot of RF generators have external modulation inputs, but the distortion level is usually high and the maximum modulation is around 30%. Some older ones will do better. I have a 1937 Ferris for instance that uses a small transmitting tube in its output stage (an 802), plate-modulated by a pair of push-pull 6L6s. That thing is practically a broadcast transmitter (and about as heavy as one too).
You're peaking the radio's passband on one of the transmitted sidebands, and off the other. Both sidebands carry the same signal, so you can afford to lose one.
A lot of RF generators have external modulation inputs, but the distortion level is usually high and the maximum modulation is around 30%. Some older ones will do better. I have a 1937 Ferris for instance that uses a small transmitting tube in its output stage (an 802), plate-modulated by a pair of push-pull 6L6s. That thing is practically a broadcast transmitter (and about as heavy as one too).
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