Cubic Astro 103


I finally found an Astro 103 on eBay from a fabulous seller who understated its flawless condition.

;     The Astro 103 is an Astro 102BX with the following updates:


Matching Network Speaker/Power Supply

 General Specifications

Frequency Coverage:

Frequency Control: Dual PTO (permeability tuned oscillator) with 6 digit frequency counter and RIT control.

PTO Modes of Operation:

Modes of Operation: 

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:

Dimensions: Power Connector: Antenna Connector: UHF type, SO-239

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

External Relay: RCA jack, grounded when keyed.

Key: RCA phono jack.

EXT Modulation: RCA phono jack.

Fuse: 3 Ampere fast blow

External LO: RCA phono jack

Auxiliary Antenna: RCA phono jack.  Slide switch chooses auxiliary receive antenna or common antenna with transmit.


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

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

Image Rejection: Better than 60dB

Receiver Selectivity:

Passband Tuning: Dynamic Range:  AGC greater than 100dB; third order intercept +5dBm.  (IMD products down 90dB at -40dBm input)

Audio Output Power:  Greater than 3 watts into 4Ω.

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


Circuit Design: Conversion from 9.00165MHz IF.  ALC limits SSB peak output power and CW power to 100 watts.

Power Input: 235 watts PEP at 13.8 VDC supply.

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

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

Harmonic Output: 45dB below peak power level

Carrier Suppression: 50dB below peak power level

Transmit Control:

Microphone Input: 47KΩ input impedance.

Audio Response: 300 → 3000Hz, ±6dB

Meter: Reads peak power on transmit selected by meter switch; forward power 100 watts full scale, reflected power 10 watts full scale, or ALC (Automatic Level Control).

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.

VSWR Shutdown:

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