User manual YAESU RF UTUNING KIT

[. . . ] (see illustration) Miss-connection will not damage the RF TUNING KIT. Connect the color-coded control cable(s) between the CNTL OUT and CNTL IN jacks (see illustration). Confirm all connections before turning on the transceiver. If the FT-2000 does not operate and the frequency display blinks sometimes, confirm and correct the "CNTL IN" and "CNTL OUT" connections. [. . . ] The -Tune circuit will automatically align itself to your operating frequency. µ-Tune Filter is activated The VRF circuit will engage when you choose an amateur band which is not connected to a -TUNE UNIT. Now rotate the [VRF] knob to peak the response (background noise) or reduce interference. Top Band Edge You may observe the relative peak point of the -Tune filter in the Tuning Offset Indicator on the display while tuning the Bottom Band Edge [VRF] knob. The amount of change in the center frequency of the -Tune filter, when rotating the [VRF] knob by one click, can be configured using Menu item "035 GEnE T DIAL DIAL. " 035 3. Press the [VRF] button (momentarily) once more to disengage the Tune filter. The " " icon will turn on in place of " " icon. In this mode, only the fixed bandpass filter for the current band will be engaged. "VRF" icon Tuning Offset Indicator [VRF] button µ-TUNE AND VRF: COMPARISONS TO FIXED BANDPASS FILTERS µ-Tune Inspection of the illustrations to the right will demonstrate the profound advantage of the -Tune circuit. In illustration [A], the gray area represents the passband of a typical fixed bandpass filter covering the 1. 8 ~ 3 MHz range; this is typical of the kind of bandpass filter found in many high-quality HF receivers today. Note also the hypothetical distribution of signals across the 160-meter band. In illustration [B], note the narrow white segment within the gray passband of the fixed BPF. These narrow segments represent the typical bandwidth of the -Tune filter, and one can see that the passband has been reduced from about 750 kHz in the case of the fixed BPF) to a few dozen kHz when -Tune is engaged. The vast majority of the incoming signals are outside the passband of the high-Q -Tune filter, and they will not impinge on any of the RF/IF amplifiers, the mixers, or the DSP. Very strong out-of-band signals like this can cause Intermodulation, blocking, and an elevated noise floor for a receiver. A 1. 8MHz 2. 5MHz FRONT-END BAND WIDTH B 1. 8MHz TUNE BAND WIDTH 2. 5MHz Main Tuning Dial knob [VRF] knob QUICK NOTE The permeability-tuning concept utilized in the -Tune circuit dates back many decades, as it was incorporated in such classic transceivers as the FT-101 and FT-901 series, in addition to the FTDX 401 and similar models. The -Tune circuit in this RF TUNING KIT is the highest development of this circuit concept ever employed in an Amateur transceiver, and is adopted in our highest-grade transceiver FT DX 9000 series. VRF In this example, illustration [a] depicts a typical fixed bandpass filter covering 14. 5 to 22 MHz, and once again the gray shaded area depicts the fixed bandpass filter's frequency coverage. The vertical lines in the illustration represent hypothetical signals throughout this frequency range. Figure [b] shows the same fixed BPF, with the white area representing the typical passband of the VRF filter operating in the same frequency range. [. . . ] You may always observe the peak point of the -Tune filter in the Tuning Offset Indicator on the display via Menu item "010 diSP 010 SEL. " BAR SEL While -Tune is a superior RF preselection circuit, it may be disabled via the Menu on the FT-2000; if this is done, the VRF circuit will engage when the [VRF] button is pressed. To disable -Tune, enter the Menu item "035 GEnE T DIAL of the FT-2000 then DIAL" 035 set the selection to "OFF. " ADVICE With -Tuning, the center frequency of the filter is continuously adjustable throughout its operating range. The quality L/C components ensure high Q of the circuit and a tight passband. The RF preselection design task required the selection of quality L/C components, but the crafting of a tuning mechanism and tuning concept that preserves system Q while providing consistent smooth automated tuning over a wide operating frequency range. [. . . ]