Vertex Standard FT-2000 manual 52

CONVENIENCE FEATURES

RECEIVER OPERATION (FRONT END BLOCK DIAGRAM)

The FT-2000includes a wide range of special features to suppress the many types of interference that may be encountered on the HF bands. However, real world interference conditions are constantly changing, so optimum setting of the controls is somewhat of an art, requiring familiarity with the types of interference and the subtle effects of some of the controls. Therefore, the following information is provided as a general guideline for typical situations, and a starting point for your own experimentation.

The FT-2000’s interference-fighting circuitry begins in its “RF” stages, and continues throughout the entire receiver sec- tion. FT-2000allows configuration of the features described below. However, the Sub band (VFO-B) receiver does not have the DSP (Digital Signal Processor) features.

VRF (SEE PAGE 53)

On the 1.9 - 28 MHz Amateur bands, Yaesu’s powerful VRF (Variable RF Filter) preselector circuit provides excellent suppression of out-of-band interference, with a passband much narrower than that provided by traditional fixed bandpass filters.

R.FLT (IF Roofing Filters) (SEE PAGE 54)

On the Main (VFO-A) receiver, three automatically-selected Roofing filters, in bandwidths of 15 kHz, 6 kHz, and 3 kHz, are provided in the 69 MHz First IF, right after the first mixer. These filters provide narrow-band selectivity to protect the following IF and DSP stages, and the filters' automatically-selected bandwidths may be manually changed by the operator, if desired, for special operating circumstances.

The Sub (VFO-B) receiver’s 40 MHz IF includes a fixed Roofing filter, with a bandwidth of 15 kHz.

CONTOUR Filter (SEE PAGE 55)

The DSP Contour filter is a unique capability on the Main (VFO-A) receiver, providing either nulling or peaking of tunable segments of the receiver passband, so as to suppress interference or excessive frequency components on an incoming signal, or to peak those tunable frequency segments. The amount of nulling/peaking, and the bandwidth over which it is applied, are adjustable via the Menu.

IF SHIFT (SEE PAGE 56)

The passband center frequency response of the IF DSP filtering may be adjusted using this control.

IF WIDTH (SEE PAGE 57)

The width of the IF DSP filtering may be adjusted using this control.

IF NOTCH (SEE PAGE 58)

The IF Notch filter is a high-Q notch filter that can significantly reduce, if not eliminate, an interfering carrier. The Q (sharpness) of the filter may be adjusted using the Menu.

DNR (DIGITAL NOISE REDUCTION) (SEE PAGE 59)

The DSP’s Digital Noise Reduction (DNR) feature utilizes sixteen different mathematical algorithms to analyze and suppress different noise profiles encountered on the HF/50 MHz bands. Choose the selection that provides the best noise suppression, which concurrently will allow the signal to rise up out of the noise.

DNF (DIGITAL NOTCH FILTER) (SEE PAGE 59)

When multiple interfering carriers are encountered during reception, the Digital Notch Filter can significantly reduce the level of these signals.

AGC (SEE PAGE 62)

The AGC system is highly adaptable to changing signal and fading characteristics, making reception possible under the most difficult conditions.

SLOPED AGC (SEE PAGE 63)

The Sloped AGC system on the Main (VFO-A) receiver, instead of clamping a fixed upper bound on audio output across a wide range of input signals, actually allows the audio output to rise, very gently, with ever-increasing signal strength. This capability allows you to separate sig- nals, using your brain, according to signal strength in addition to slight frequency differences.

IF Filter Quality Adjustment (SEE PAGE 121)

The “Q” (quality factor) of the IF DSP filters may be adjusted using the Menu.

Variable IF Filter Shape Factor (SEE PAGE 121)

You may adjust the shape factor of the receiver IF DSP filters using the Menu.

					Main Band (VFO-A)
		RF		1st IF	2nd IF		3rd IF (DSP)
	THRU			69.450 MHz	450 kHz		30 kHz
	OPTION		IPO OFF	ROOFING
				FILTER
ATT	µ-TUNE	BPF	RF AMP 1	1st	CF	2nd	DSP
				IF AMP		IF AMP	UNIT
ANTENNA				3k/6k/15k
				1st Local	2nd Local		3rd Local
SELECTOR	VRF		RF AMP 2

	Sub Band (VFO-B)
1st IF	2nd IF
40.455 MHz	455 kHz
ROOFING
FILTER
1st	CF	2nd	DET
IF AMP		IF AMP
15k
1st Local	2nd Local

Page 50 FT-2000 OPERATING MANUAL