Product Description
The SP-767 is a high-fidelity audio transducer incorporating manual frequency tailoring, specifically intended for amateur and general communications modes, as well as for broadcast listening. It features wideband functions for music and FM reception.
The unit offers independently adjustable low-cut and high-cut filters, providing twelve possible audio response configurations selectable from the front panel. This allows operators to match the audio to their listening preferences under various conditions and modes.
The SP-767 includes two separate inputs, selectable via a front panel switch. An output for headphones is also provided on the front panel, enabling the use of the frequency tailoring capabilities with separate headphones.
Filter Operation
The low-cut filter selector includes two filter positions in addition to the "NORM" position, while the high-cut filter selector includes three, plus “NORM". The response graph on the front panel indicates which combination of positions to use for each mode being received.
AM, FM
These wideband modes usually call for maximum audio bandwidth and maximum fidelity. Set both filter selectors to NORM. However, should very low or very high frequency interference appear due to nearby stations, manmade or atmospheric noise, adjust the filter selectors accordingly to maintain pleasant reception.
SSB
For the most natural sounding reception of these signals, set the LOW selector to the NORM position, and the HIGH selector to position 1. Again, under crowded band conditions or high noise levels, it will be advantageous to reset these controls for best overall reception.
CW
In this narrow mode, the LOW selector should be set to position 2 and the HIGH selector to position 3, resulting in a narrow audio response centered around 600 to 700 Hz. This filter characteristic is useful for CW reception with receivers that do not include narrow filters in their IF circuits, as well as ideal for cutting any residual internally generated noise from the latter stages of receivers using very narrow CW filters.
Specifications
Speaker Element
- Diameter: 120 mm
- Power Rating: 3 watts
- Impedance: 8 ohms
- Frequency Range: 100 - 1200 Hz
Filter Circuit Selections
| Filter | Frequency Response |
|---|---|
| LOW 1 | below 300Hz (-6db/octave) |
| LOW 2 | below 600Hz (-6db/octave) |
| HIGH 1 | above 2.4kHz (-6db/octave) |
| HIGH 2 | above 1kHz (-6db/octave) |
| HIGH 3 | above 700Hz (-6db/octave) |
General
- Case Dimension (HWD): 120 × 200 × 306 mm
- Weight: 2.2 kg
Circuit Diagram Description
The schematic diagram illustrates the internal circuitry of the PB-2380 filter unit, which is integral to the SP-767's audio tailoring capabilities. It details the connections for the speaker (SP1), headphone jack (J1), output jack (J2C), and dual input jacks (J2a, J2b). Key components include inductors L1 (0.68mH) and L2 (1.5mH), and capacitors C1 (33 μF) and C2 (33 μF). Selector switches S1, S2, and S3 are shown controlling the low-cut filter (positions NORM, LOW 1, LOW 2) and the high-cut filter (positions NORM, HIGH 1, HIGH 2, HIGH 3), enabling various frequency response configurations.
YAESU MUSEN CO., LTD.
C.P.O. BOX 1500
TOKYO, JAPAN
