Note
QST, Apr 1960, p. 103. (available in May)
QST, May 1960, p. 117.
QST, Jun 1960, p. 99.
QST, Jan 1964, p. 175.
CQ, Feb 1964, p. 93.
The Hammarlund HX-500 is a 100-watt AM/CW/SSB transmitter for amateur and commercial use on the 3.5, 7, 14, 21 and 28 to 30 MHz bands. It uses 21 vacuum tubes, 4 semiconductor diodes.
The VFO tuning mechanism is gear-driven to eliminate backlash. A dial drag/lock knob allows operators to adjust the tuning torque or lock the dial to a specific frequency.
– VFO Range: 500 kHz.
– Tuning Rate: 20 kHz per complete single rotation of the tuning knob.
– Dial Accuracy: Main slide-rule dial indicates down to 10 kHz increments; tuning knob skirt is calibrated to better than 200 Hz.
Features
– Separate dial scale for each band, or portion of 10 band.
– All crystals included for all amateur bands.
– Frequency readability to 200 Hz, or better.
– Stability after warm-up better than 100 Hz.
– Modes: USB, LSB, DSB, CW, FM, FSK for RTTY plus 40 Hz identification keyed shift.
– ALC adjustable to prevent overdrive.
– 50 ohm fixed pi output.
– Built-in antenna changeover with receiver antenna input connection.
– Adjustable RF level controls output power when employed with high power linear.
– TVI suppressed.
– Provision for metering final plate current.
– ALC and VOX.
Output power
– SSB: 70–100 watts PEP
– CW: 70–100 watts
– FSK: 70–100 watts
– FM: 70–100 watts power output.
– DSB / AM: 17–25 watts
Specifications
– Carrier Suppression: Better than -50 dB.
– Unwanted Sideband Suppression: Better than -50 dB.
– FSK Deviation: Adjustable up to 2 kHz (typically set to 850 Hz); features an automatic 40 Hz identification shift for CW ID.
– 3rd and 5th order distortion products down 30 db or better.
– Spurious frequencies down 50 db or better.
– Self-balancing diode balanced modulator.
– Overall audio response 300 to 2300 Hz.
– 60 kHz filter type SSB generator.
Uses a parallel pair of fan cooled 6146 beam power pentodes operating in Class AB1.
The output tank circuit matches a 52-ohm transmission line and is designed to suppress TVI.
Includes a built-in T/R antenna changeover relay with an external connection to disable the station receiver during transmission.
Tube LIneup
6AU6: 60 kHz Oscillator
6EW6: 60 kHz Amplifier
6U8: Crystal Oscillator - 1st Mixer
12BY7: Reactance Modulator
12AX7: 1st and 2nd Audio Amplifier
6CM7: 3rd Audio Amplifier / VOX Amplifier
6AL5: VOX Diode / Anti-Trip Diode
6U8: Anti-Trip Amplifier / Relay Amplifier
6U8: VFO / 2nd Mixer
(2) 6CB6: Bandpass Amplifier
6EW6: 3rd Mixer
6C4: H.F. Crystal Oscillator
12BY7: R.F. Amplifier - Driver
(2) 6146: Final R.F. Power Amplifier
6AL5: ALC Bias Rectifier
(2) 12AX4: High Voltage Rectifier Diode
6CA4/EZ81: Low Voltage Rectifier
0A2: Voltage Regulator
Power Requirements: 105–125 VAC, 50–60 Hz.
References
Review: QST, Oct 1960, p. 45.
