AMPLITUDE MODULATION HIGH FIDELITY

The Output of an AM Transmitter with 100% Modulation

 This site was started to promote AM transmission on the Broadcast Band.
It has been extended to cover other interests - vacuum tube design and early recording equipment

AMPLITUDE MODULATION

  The properties of both AM and FM are developed both intuitively and mathematically in the introduction.
The design of a solid state AM tuner with a maximum bandwidth of about 38KHz. and neglgible distortion is described in detail.
A low power vacuum tube transmitter with matching characteristics is also described.
A regenerative receiver employing 2 volt filament tubes rounds out the section on AM receivers.
A sample of audio from both receivers is included.
A short history of the Brisbane national vacuum tube AM transmitters 4QG and 4QR is given along with design details.
Sample audio from these transmitters is included.
The first Brisbane FM transmitter in 1953 is also covered.

DESIGN of VACUUM TUBE EQUIPMENT

  The design of vacuum tube equipment is rapidly becoming a lost art.
The detailed design of the following vacuum tube equipment is included:-

 [1] A push-pull 6V6 audio amplifier

 [2] A push-pull 6L6 audio amplifier

 [3] A high performance low power AM transmitter

 [4] A two tube regenerative receiver with audio samples

 [5] An Australian radio receiver from the forties

 [6] A high performance Voltage Regulator

 [7] A Vacuum Tube Preamplifier and Disc Equaliser

 [8] A Vacuum Tube Universal Tone Control

 [9] A History of the Brisbane Vacuum Tube Broadcast Transmitters
  AM 1925 to 1990
  FM 1953
  The Interaction between Transmitter and Receiver Design

ACOUSTIC and EARLY ELECTRICAL RECORDERS

  The detailed design of the following equipment is discussed:-

 [1] Edison Vertical [ Hilland Dale ] Recorders
 [1A] Audio tracks are included to illustrate the above

 [2] Vertical Recorders with Negative Feedback
 [2A] Audio tracks are included to illustrate the above

 [3] Henry Harrison's 1926 Recorder
 [3A] Audio tracks are included to illustrate the above

 [4] The WE4A Reproducer
 [4A] Audio tracks are included to illustrate the above

 [5] Early Australian Pickups - The CE and MBH

INTRODUCTION


HIGH PERFORMANCE AM TUNER


LOW POWER AM TRANSMITTER


REGENERATIVE RECEIVER


6V6 PUSH-PULL AMPLIFIER


6L6 PUSH-PULL AMPLIFIER


WE4A WESTERN ELECTRIC PICKUP


EDISON VERTICAL [HILL and DALE]

ACOUSTIC RECORDING


AIRZONE VACUUM TUBE RECEIVER


HIGH PERFORMANCE VOLTAGE REGULATOR


PREAMPLIFIER and DISC EQUALISER


UNIVERSAL TONE CONTROL


BRISBANE VACUUM TUBE TRANSMITTERS


ERRORS and QUESTIONS

CONTACT



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