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The EXPANDER 160 is a compact crystal oscillator unit which allows remote controlled selection of up to four different crystals. This provides new injection signals for loop mixing in PLL synthesizer circuits, or additional synthesizer frequencies in 23-channel CB transceivers. A unique system of wire jumpers allows the EXPANDER 160 to be used solely as a crystal switch, with the oscillator circuit disconnected. This configuration is needed for all 23-channel crystal-synthesized radios, and all 40-channel PLL radios whose crystal frequency is doubled or tripled before mixing with the VCO signal. See the Schematic Diagram on Page 9. The EXPANDER 160 consists of a Colpitts oscillator, bipolar buffer stage, a diode switching array, and various jumper wire options. One of four crystals is chosen when a DC voltage is applied through your hard switch (toggle, rotary, slide, CB/PA, etc.) to one of the PC board holes numbered “1” through “4.” The “5” hole is the common hot side for the hard switch, and connects directly to the radio’s regulated +DC supply bus. ASSEMBLY INSTRUCTIONS PLEASE READ CAREFULLY BEFORE PROCEEDING! Assembly consists of stuffing the parts into the proper PC board holes, as illustrated in the X-Ray View drawing, Page 10. Check against the schematic circuit diagram if you’re in doubt about the correct holes. Push all parts down tight, wiggling back and forth if necessary as you press down. (See photo, Page 11.) The diodes and resistors will bend naturally to the proper hole spacing. If you already have crystals with different specs, they can be tried first and will usually work. If you have the plug-in HC25/U types, these can also be used by drilling out the PC board holes to fit their thicker pins. The 40-channel CB band has a total bandspread of 440 KHz (27.405 MHz - 26.965 MHz = 440 KHz); the older 23-channel PLL radios have a bandspread of 290 KHz (27.255 MHz - 26.965 MHz = 290 KHz.) For continuous expanded range, each new crystal must add or subtract 450 KHz or 300 KHz respectively, to the preceding crystal.
Tags : synthesizer circuits, colpitts oscillator, wire jumpers, oscillator circuit, cb band, crystal oscillator, channel cb, jumper wire, wire options, channel crystal, bus assembly, schematic circuit diagram, switch construction, crystal frequency, ray view
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