Ramsey Electronics QRP-80 Manual de instrucciones descargar pdf (Pagina 5)

HR-80• 5

Therefore, we are pleased to assure you that your manual for the HR-80

receiver and the receiver circuit itself have been designed with an

understanding of typical operating needs and expectations for the 80

meter band.

This receiver circuit is ideal for discovering just how simple a true

“Communications Receiver” can be . That’s right- there is a BIG

difference between the Ramsey HR-80 and other simple short wave

radio circuits we can try to build.

Yet it is very easy to build. Our HR-series are by far the easiest to build

of all the Ramsey kit receivers and therefore very nice for radio

newcomers. Consequently, our manuals for the 40 and 80 meter

receivers are written with beginners in mind, since both of these bands

offer Novice and Technician privileges. The manuals for the 30 and 20

meter versions assume the general Ham radio know-how that should

accompany a General Class or higher license.

ABOUT DIRECT CONVERSION RECEIVERS:

The HR-80 is a “Direct Conversion” receiving circuit. There is no need

for IF(intermediate frequency) circuitry. The receiver “processes” the

incoming signal right at its own frequency, with no need to mix or

transform it with additional internal oscillators and amplifiers running at

intermediate frequencies such as 455 KHz.

The advantage of this type of receiver is that it permits tuning of CW,

AM and SSB signals with no need for a separate BFO. (A BFO or “beat

frequency signal oscillator” is an entirely separate oscillator circuit used

in the IF “intermediate frequency” section of a superhetrodyne receiving

circuit). Since this frequency is designed specifically for SSB and CW,

you will also hear the carrier signal of any AM shortwave broadcast

station.

The most elementary “DC” receiver consists of just an oscillator and an

antenna connected to the inputs of a “Product Detector” whose tiny

audio output is then amplified for listening. A product detector can be

made from simple diodes, or a pair of transistors, or a dual gate FET

transistor, or various IC’s. The Ramsey HR-80 efficiently utilizes the

Signetics NE602 IC for both the tunable oscillator and the product

detector circuits, giving the equivalent of seven transistors in the mixer-

oscillator stages.

1 2 3 4 5 6 7 8 9 10 ... 26 27

Sin comentarios

Ramsey Electronics QRP-80 Manual de instrucciones Pagina 5