Vertex Standard FT-1000MP manual Advice on QRM Reduction, Clarifier RX/TX Offset Tuning

OPERATION

DEALING WITH INTERFERENCE

CLARIFIER (RX/TX OFFSET TUNING)

The three CLAR buttons near

the lower right corner of the front panel, and the control just above them, are used to offset either the receive, transmit, or both fre- quencies from their settings on the main display. The three small numbers in the center of the dis- play (just to the right of the main

frequency display) show the cur-

rent Clarifier offset. The Clarifier controls on the MARK- V FT-1000MPare designed to allow you to preset an offset (up to ±9.99 kHz) without actually retuning, and then to activate it with the Clarifier’s RX and TX but- tons.

Perform the following steps, if you like, to familiar- ize yourself with the Clarifier controls:

rWithout pressing any of the Clarifier buttons, rotate the CLAR knob back and forth while watching the small center display. Notice that the small digits change, indicating the preset Clarifier offset (which hasn’t been applied to the Tx or Rx frequency yet) while the main display remains unchanged.

rIf you press the Clarifier TX button, “CLAR”-“TX” appears below the smaller offset display, and if you press the PTT you will see the Tx frequency shift by the amount of Clarifier offset.

rIf you press RX instead, notice that “RX”-“CLAR” appears and the frequency offset is applied and the display shifts to the offset receive frequency accord- ingly. Press the PTT switch, and notice that the

transmit frequency remains the same as the origi- nal frequency display when the receive Clarifier is on. You can reset the offset to 0.00 kHz at any time by simply pressing CLEAR.

rWith the RX Clarifier active, the center tuning marker just above the main frequency display moves to the right or left as you change the offset by rotating the CLAR knob. Also notice that the main frequency and the Clarifier offset displays change together.

rNow press the Clarifier CLEAR key and observe that the offset is cleared to zero, and the Main VFO frequency returns to what it was originally.

The Clarifier is commonly used when you are in contact with a station whose transmitter drifts (or per- haps you didn’t have him quite tuned in when you called him). You don’t want to change your transmitting fre- quency, as that would force him to retune - you just want to adjust your receiver.

Another application for the Clarifier is in a casual DX pile-up situation, where the DX station is listening in a “Split” mode (but listening “UP 5” or a similar split of less than 10 kHz). In this case, you leave the main receiver on the DX station’s frequency, then use the RX Clarifier to tune the pile-up area, listening for the station currently in QSO with the DX station. When you find that station, you can switch the TX Clarifier On and the RX Clarifier Off; you will now be receiving back on the DX station’s frequency, but you will be transmit- ting on the frequency where the DX station probably is still listening. See the discussion on page 56 regarding the use of the SPOT control for CW spotting; it speeds up the above process significantly.

Advice on QRM Reduction

Use the BANDWIDTH buttons and then the SHIFT and WIDTH controls to suppress interference. Their use varies somewhat from mode to mode.

When you are ready to retune to a new frequency, you may wish to return the SHIFT and WIDTH con- trols to their default positions (center detent). The WIDTH control can also be turned counter-clock- wise to reduce the IF bandwidth more gradually, and then the SHIFT control can be turned left or right from center to shift the center frequency lower or higher, as depicted in the drawing.

For digital modes, the wider bandwidth selections are fine for tuning around, but the 500 or 250 (Hz) bandwidths will generally give the best copy with narrow shifts. If you have the RTTY and PKT menu selections set to match your TNC/terminal unit (see page 55), you should not need to adjust the SHIFT

control at all, and the WIDTH control should only be adjusted with a great deal of care (to avoid los- ing the contact). See the section on digital modes in this manual for more details.

For 300-baud packet, use the 500 (Hz) bandwidth and keep the WIDTH control centered; the SHIFT control may require fine tuning either side of center for optimum copy of weak signals. Experiment with the SHIFT setting on a busy packet channel, and then note the optimum setting for all future HF packet operation (it will be the same unless you replace your TNC or recalibrate the input tones).

Note - except during extreme QRM conditions, the WIDTH and SHIFT controls should be left in their center (detent) positions when tuning the receiver to a new frequency. This will provide the best fidel- ity and easiest tuning.

MARK-V FT-1000MP Operating Manual page 49