Ramsey Electronics FM10A Manual de Instruções descarregar pdf (Página 4)

VLF1 • 4

INTRODUCTION

You have a great setup, tuning in just about everything in the spectrum. You

go up and down, down, down, until...DOH! Your receiver bottoms out. Ever

wonder what was down there just under your rig’s lower limit? You need a

very easy to build and easy to set up frequency converter, so you can delve

in to all the wonders that reside in

The Low Frequencies. Well, there’s some

cool stuff down there and that’s what the VLF1 is all about: a kit that Ramsey

Electronics is only too happy to provide for you.

You’ll notice that the PC board included with your kit is single sided. It is easy

to assemble and a quick look at the parts list reveals 2 ICs and a handful of

resistors and caps. This kit uses both digital and analog circuitry to step up a

low frequency RF signal to a 4MHz minimum.

VLF1 CIRCUIT DESCRIPTION

Before we begin dissecting the circuit, let’s have a look at the “big picture”

and see what it is that we’re trying to accomplish.

Without getting too much into detailed theory, we need to “mix” the incoming

low frequency signal with a high frequency one to produce an output that

your receiver can use. As shown in the diagram below: the low frequency

input RF signal is added to a high frequency (4MHz) clock producing a high

frequency signal.

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Ramsey Electronics FM10A Manual de Instruções Página 4