Inhaltsverzeichnis
Hammarlund SP-600-JX / Super Pro SP-600
Manufactured by Hammarlund Mfg. Co., New York NY.
The Super Pro / SP-600 is the latest set in Hammarlund's Super Pro series, it was was mainly produced from 1951 to 1961 and there exists a large number of SP-600 variants for the military and civilian market.
Technical data
- Frequency range: 0.54 - 54 MHz (variants with different frequency coverage)
- Frequency display: Analogue dial, 25 - 50 kHz
- Frequency memory: none
- Sensitivity: AM (A3) < 2 μV, CW < 0.75 μV / Selectivity: 0.2 / 0.5 / 1.3 (crystal)/ 3 / 8 / 13 kHz (-6 dB)
Power supply
- Mains operation: 110, 220 V
Dimensions
- Rack version: 480 x 266 x 440 mm, weight 30 kg
Accessories
Operation
The set is a veritable boat anchor, weighing 39.4 kg in the 55 x 32 x 44 cm desktop version and 30 kg when is comes as the 48 x 26.6 x 44 cm rack version. The receiver can be operated with different supply voltages from 90 - 270 V, 50-60 Hz, in certain J versions 25 - 60 Hz and has a power consumption of around 130 watts.
The front panel is dominated by the two dials and the tuning knobs. The band switch under the left-hand dial also moves a pen-like pointer that indicates the band segment set, the large button on the right operates the main tuning, the logging scale in the right-hand dial window is mechanically coupled to the main tuning and gives good returning accuracy to return to a station on a known frequency which has been tuned in before. The frequency accuracy on the main dial in the 49m band is around 25 kHz, in the higher frequencies it is significantly worse, for example in the 19m band around 50 - 100 kHz. The tuning can be mechanically locked with the TUNING LOCK button.
The RF gain switch, which is connected to the mains switch, is used to turn on the radio; it controls the RF gain as long as the AVC switch in the bottom right-hand corner is set to MAN(ual). The volume control (audio gain) is located in the middle between the band selector and the main tuning.
The BFO control for CW reception is also located in the right lower corner of the front panel, the BFO frequency can be adjusted using the BEAT OSC control, the AGC characteristic is altered for CW reception. In the right upper corner of the sets with X suffix, there is a switch for six crystal-controlled fixed frequencies with a corresponding memory table and a fine tuning control. The required crystal frequency in ranges 2 and 3 is the desired receive frequency + 455 kHz, in ranges 4 and 5 a third of the value of (desired receive frequency + 3955) (third harmonic of the crystal frequency - IF 3955 kHz).
The SP-600-J-4 / R-320A has a control for the IF gain at the same position.
The headphone socket is located at the bottom left of the front panel between the switches for transmit/receive mode (together with a suitable transmitter) and the noise limiter. The SP-600 does not have a built-in loudspeaker. The SELECTIVITY and PHASING controls ares used for bandwidth and notch frequency control of the crystal filter active in the three narrow IF bandwidths. The instrument can be switched to display the RF and AF levels using the small toggle switch.
Technical principle
The RF signal coming from the antenna is first amplified in two stages (V1 and V2, each 6BA6), in the first mixer (V5: 6BE6) either the signal from the crystal oscillator (V3: 6AC7) for fixed frequency reception or the signal from the VFO (V4: 6C4) is mixed and the signal is converted to the intermediate frequency of 455 kHz in bands 1 - 3 and then amplified (V7: 6BA6). In bands 4 and 5, the first IF is converted to 3955 kHz and after that step converted to 455 kHz second IF with the signal from a 3.5 MHz oscillator (V8: 6C4) in the second mixer (V6: 6BE6).
After passing through the IF filter bank, the signal is amplified in two stages (V9: 6BA6 / V10: 6BA6) and fed to the demodulator via a driver stage (V11: 6BA6). The AGC control signal is picked up here (V14B: 1/2 6AL5) and, in certain variants (V16A: 1/2 12AU7), fed to an IF output for further processing.
The second system of V14A (1/2 6AL5) acts as a diode demodulator; the BFO signal (oscillator V13: 6C4 / amplifier V12: 6BA6) is also mixed in here.
After branching off the signal for the noise limiter (V15A: 1/2 6AL5), the audio signal is fed to the AF preamplifier (V16B: 1/2 12AU7) and audio final amplifier (V17: 6V6GT).\
V15B (1/2 6AL5) is used as rectifier to indicate the AF level. V19: 5R4GY acts as a mains rectifier, a voltage stabiliser V:18 0A2, the RF GAIN is changed by changing the grid bias voltage via V20: 6AL5.
Components
The set is hollow state.
Technical documentation
The technical manual TM 11-851 describes the technical design of all stages in detail and is illustrated with schematic diagrams.
Development
On the nameplate, which can be found on the cover of the HF unit, a J means that components in accordance with JAN (Joint Army Navy - Standard) are installed, an X means that crystal controlled fixed frequencies are provided, and an L means that the set covers the long-wave range (used for aircraft beacons in the USA) instead of the full medium-wave coverage. Further information on the individual variants (based on the compilation by Les Locklear) can be found > > > here < < <.
