The Astro 150A is very similar to the Swan 100MX, but with two functional enhancements: a digital synthesizer and new features for the CW operator.

Digital Synthesized Tuning

The transceiver tunes in 100 Hz steps.  The “FINE” control allows the operator to adjust the TX/RX frequency to any frequency between those steps. The synthesizer is controlled by an Intel 8048 microcontroller chip.

The rig can be tuned in one of two ways.  The matching microphone has two pushbuttons which adjust the transceiver’s frequency up or down in 100 Hz steps.  Holding either button down tunes the radio at a rate of 100 Hz per second.  Because the synthesizer’s lock-up time is relatively long, tuning is smooth much like an analog PTO or VFO.

Acclamation to the 150A’s unconventional tuning system is not easy.  The tuning knob is connected to an Allen Bradley type AB potentiometer.  When in the twelve o’clock position, the radio’s frequency is fixed.  A slight clockwise rotation of the knob tunes the transceiver up in frequency at a rate of 100 Hz/second.  The tuning rate increases as the control is turned further clockwise, up to a maximum of rate of 100 KHz/second at the pot’s end of rotation near it’s five o’clock position.  In a similar manner, counterclockwise rotation from the twelve o’clock position causes the synthesizer to tune down in frequency.  I understand Yaesu’s “shuttle jog” tuning system works in a similar manner.

The first enhancement for the CW operator was the addition of full break-in (QSK) for CW operation.  QSK performance is reliable and smooth.

The second enhancement is the addition of a discreet two pole CW filter.  The filter is placed in line with the SSB filter for a total of 10 poles of filtering when the mode switch is in the CWN position.  The filter is tunable during alignment and has additional circuitry for gain EQ.  I tuned mine for a CW note of 550 Hz, rather than the default 800 Hz tone.

• PSU-5B Matching speaker/power supply
• ST-3 Antenna tuner

• 160M     1.8 - 2.4 MHz (Model 151)
• 80M       3.5 - 4.0 MHz
• 40M       7.0 - 7.5 MHz
• 20M   14.0 - 14.5 MHz
• 15M   21.0 - 21.5 MHz
• 10M   28.0 - 30.0 MHz (Model 150)

Modes of Operation:  SSB with selectable sideband.  CW with automatic 800 Hz offset in transmit, with full or semi break-in.

Power Input:  12-14 VDC negative ground only.  No damage will occur over the range of 10 to 15 VDC.  20 Amperes peak current required.

Electromagnetic Interference Reduction:

• Transmit:  Three pole bandpass filter on each band suppresses out of band products. Five element low pass filter on each band suppresses harmonics.
• Receive:  Three pole bandpass filter on each band suppresses IF, image, and spurious signals.

• Height - 3.75"  (9.53 cm)
• Width - 9.75"  (24.8 cm)
• Depth - 11.75"  (30.2 cm)
• Weight - 13 lb.  (5.9 kg)

• Pin 1   13.6 VDC
• Pin 2   Ground
• Pin 3  Ground (used for tuner meter lamps)
• Pin 4  13.6 VDC
• Pin 5  Ground
• Pin 6  13.6 VDC (for tuner meter lamps, fused 2A)

External Speaker/Phones:  ¼" Phone jack; 4-8 ohms.

External Relay:  RCA jack, grounded when keyed.

Fuse:  2 Ampere fast blow, protects some internal circuitry and accessory power; external 20 ampere fast blow fuse required for full current and reverse voltage protection.

Circuit:  Single conversion to 9.00165 MHz IF using double balanced mixer, exceptional immunity to overload and cross modulation.

Sensitivity:  0.35µV for 10dB S+N/N ratio.

Selectivity:  8 pole crystal bandpass filter.  Bandwidth of 2.7 KHz at 6dB points, 4.3 KHz at 60dB points; 1.6:1 shape factor.

Internally Generated Spurious Responses:  0.5 µV or less equivalent input signal.

AGC:  6dB change in audio level over input range of 1.0µV to 0.1V (100dB)

Audio Output:  3 watts available at less than 10% distortion; 300-3000 Hz; 4 ohms impedance.

Meter:  “S” units from 1-9; 20, 40, 60 dB over S-9.

Circuit:  Balanced modulator at IF, crystal filter, single conversion to output frequency.

Power Input:  235 watts PEP at 13.8 VDC supply.

Power Output:  100 watts PEP into 50 ohm non-reactive load at 13.8 VDC supply voltage.  ALC limits peak power to 100 watts PEP.

Unwanted Sideband Rejection:  60dB down at 1000 Hz audio frequency.

Harmonic Output:  50dB below peak power level

Carrier Suppression:  50dB below peak power level

Transmit Control for SSB:  PTT or VOX standard

Transmit Control for CW:  Full or Semi break-in with sidetone standard.  Automatic 800 Hz offset on transmit frequency.

Microphone Input:  47K ohms input impedance.

Audio Response:  300 - 3000 Hz, ±6dB

Meter:  Reads peak power on transmit.

Cooling:  Large capacity heat sink fins supplied.  For SSTV, RTTY, and semi continuous transmitting, forced air cooling supplied by a “muffin” type fan on heat sink fins is required.

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