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Lowe HF-225 User Manual

Lowe HF-225
35 pages
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Lowe HF-225 Specifications

General IconGeneral
BrandLowe
ModelHF-225
CategoryReceiver
LanguageEnglish

Summary

Introduction

Getting started

Aerials and Earths

Discusses suitable aerials and grounding systems for the receiver.

The Long Wire Aerial

Details the simplest aerial system, its construction, and placement.

The Half-Wave Dipole Aerial

Explains the construction and properties of a half-wave dipole aerial.

The Fan Dipole Aerial

Describes a fan dipole, a multi-band aerial configuration.

The Vertical Aerial

Covers ready-made vertical aerial systems and their suitability.

Active Aerials

Explains active aerial systems and their use with short aerials.

Loop Aerials

Discusses home-constructed loop aerials for low-frequency reception.

The Power Supply and other Connections

Details power requirements, polarity, and mains connection safety.

External Loudspeaker

Recommends external speakers and their impedance requirements.

Record Output

Explains the record output for taping stations or driving decoders.

Types of Signal

Introduces different transmission types encountered by the receiver.

AM (Amplitude Modulation)

Explains Amplitude Modulation, its use in broadcasting, and tuning.

AM Selectivity

Discusses bandwidth, signal overlap, and receiver filters for AM.

SSB (Single Sideband)

Explains Single Sideband transmissions and their types (USB/LSB).

CW (Continuous Wave, ie Morse)

Describes Morse code transmission and reception with the receiver.

RTTY (Radio Teletype)

Explains RTTY signals and the need for terminal units.

FAX (Facsimile)

Covers FAX transmission and the requirement for decoders.

FM (Frequency Modulation)

Discusses narrow-band FM reception and squelch operation.

AM Propagation and Fading

Explains AM signal fading and techniques to improve reception.

ECSS (Exalted Carrier, Selectable Sideband)

Describes the ECSS technique for improving AM reception.

AMS (Synchronous AM)

Explains Synchronous AM detection for enhanced AM reception.

Controls and Connections

Signal strength meter

Details the S-meter calibration and function.

Mode Switch

Explains the selection of six available reception modes.

AMS detector lock indicator

Describes the indicator for synchronous detector lock.

Frequency display

Details the 5-digit LCD and its indicators.

Main tuning knob

Explains the rotary control for tuning and memory selection.

Headphone socket

Describes the headphone output and its function.

Volume control and Power switch

Explains the combined volume and power control function.

Tone control

Details the audio tonal quality adjustment.

RF Attenuator button

Explains the function of the RF attenuator.

Filter select button

Describes how to change receiver bandwidth filters.

Megahertz fast tuning buttons

Explains the buttons for 1 MHz frequency increments.

Memory mode select button

Describes how to switch to and preview memory mode.

Memory mode flag

Explains the indicator for memory mode.

Memory channel mode button

Details the channel monitoring function.

Memory recall button

Explains how to recall stored frequencies.

Memory store buttons

Describes how to save current frequencies into memory.

Remote keypad jack socket

Connection for the optional K-225 keypad.

50 Ω / Whip antenna socket

Input for 50/75 Ohm coaxial cable or whip aerial.

Antenna select switch

Selects between different antenna inputs.

600 Ω antenna terminal

Connection for wire antennae without coaxial cable.

Ground terminal

Connection for earth grounding to reduce interference.

FM squelch level adjustment

Adjusts the squelch threshold for FM reception.

Record output jack socket

Provides a fixed level audio output for recorders.

External loudspeaker jack socket

Connects an external speaker, disabling the internal one.

12V DC power input socket

Connection for the external power supply.

Operating the HF-225

Volume and Tone Controls

Explains how volume and tone affect sound quality and operation.

Receiver Tuning

Details tuning methods, including rotary control and MHz buttons.

Tuning Rates by Receiver Mode

Lists normal and fast tune rates for different receiver modes.

Tuning in AMS mode

Describes specific tuning procedures for AMS mode.

Keypad frequency entry

Explains direct frequency entry using the optional keypad.

RF Attenuator

Discusses the RF attenuator's benefits and usage.

Filter Selection

Details how to select different IF filter bandwidths.

Memory Operations

Explains the 30 memory functions: preview, recall, store, channel.

Special Functions

Describes the four special functions accessed via the FN button.

Use with the Whip Antenna

Details using the whip antenna with the pre-amplifier.

FM Squelch level

Explains adjusting the FM squelch level.

Care of your Receiver

General notes

Covers common issues like microprocessor crashes and environmental factors.

Optional Units

K-225 External Keypad

Details the external keypad for frequency entry and memory selection.

D-225 Detector Unit

Explains the detector unit for FM and Synchronous AM.

B-225 Internal battery

Describes the internal battery option for portable use.

W-225 Whip Antenna

Covers the whip antenna with pre-amplifier for portable operation.

S-225 External Loudspeaker

Details the optional high-quality external loudspeaker.

Circuit description

Circuit Diagrams

Receiver specification

Frequency coverage

Specifies the receiver's tuning range.

Reception modes

Lists the supported reception modes.

Receiver system

Describes the receiver's architecture (PLL tuning, dual conversion).

Displays

Details the LCD display and signal strength meter.

Tuning

Explains tuning methods and rates.

Memories

Covers memory capacity, functions, and keypad selection.

I F filters

Lists selectable IF filter bandwidths for different modes.

Audio filters

Details the audio peak filter for CW reception.

RF attenuator

Specifies the selectable 20 dB attenuator.

Controls

Lists the primary controls and their functions.

Aerial inputs

Details the various antenna input connectors.

Audio outputs

Lists headphone, external speaker, and record outputs.

Power supply

Specifies DC supply voltage and internal battery details.

Dimensions

Provides physical size and weight of the receiver.

Receiver Performance

General overview of performance metrics.

Sensitivity

Specifies signal levels required for different modes.

Receiver Frequency

Lists sensitivity by frequency range and mode.

Selectivity

Details IF filter bandwidths and shape factors.

Dynamic range

Specifies reciprocal mixing and intermodulation effects.

Spurious responses

Lists image and fixed response rejection levels.

Frequency stability

Details frequency drift and error specifications.

AGC characteristics

Describes AGC attack and release times for different modes.

Noise blanker

Explains the noise blanker operation.

Audio output

Specifies power output levels for speakers and headphones.

Frequency response

Details frequency response curves for different filters and tone settings.

Distortion

Specifies THD for AM and SSB modes.

AMS Detector

Details lock range and audio distortion under fading.

Signal to Noise ratio

Lists S/N ratios for AM and SSB modes.

Power supply

Specifies voltage range and current consumption.

HF Band Plan

Keypad Frequency Entry Supplement