Radio Shack PRO-70 owner manual Avoiding Image Frequencies

Page 45

20-310.fm Page 45 Wednesday, August 4, 1999 10:49 AM

AVOIDING IMAGE FREQUENCIES

You might discover one of your regular stations on anoth- er frequency that is not listed. This might be what is known as an image frequency. For example, you might find a ser- vice that regularly uses a frequency of 453.275 also on 474.675.

To see if it is an image, do a little math.
Note the new frequency.	474.675
Double the intermediate frequency
of 10.7 MHz (21.400) and subtract it
from the new frequency.	–21.400
If the answer is the regular frequency,	453.275
then you have tuned to an image.

Occasionally you might get interference on a weak or dis- tant channel from a strong broadcast 21.4 MHz below the tuned frequency. This is rare, and the image signal is usu- ally cleared whenever there is a broadcast on the actual frequency.

Image 45

Contents PRO-70 50-Channel Portable Scanner Introduction Serial Number Description Frequency BandRange MHzFCC Notice Pager transmissions Scrambled or encrypted transmissions Scanning LegallyContents Troubleshooting Care and Maintenance SpecificationsGeneral Scanning Guide Power Sources Using BatteriesPreparation Fm Page 10 Wednesday, August 4, 1999 1049 AM Using Standard AC Power Using Vehicle Battery Power Charging a Rechargeable Battery Pack Connecting the Antenna Connecting an Optional Antenna Connecting AN EARPHONE/ Headphones Traffic SafetyListening Safely Using the Belt Clip Connecting AN Extension SpeakerLook AT the Keypad Understanding the PRO-70Look AT the Display Fm Page 20 Wednesday, August 4, 1999 1049 AM Operation Turning on the Scanner and Setting SquelchActive Frequency References Searching for and Storing Active FrequenciesStoring Frequencies Fm Page 24 Wednesday, August 4, 1999 1049 AM Using Band Search Fm Page 26 Wednesday, August 4, 1999 1049 AM Using Direct Search Using the Monitor Memory Listening to the Monitor MemoryMoving a Frequency from the Monitor Memory to a Channel Scanning the Stored Channels Monitoring a Stored Channel Clearing a Stored Channel Special Features Using the KeylockLocking OUT Channels Using a 2-SECOND Delay Listening to a Weather Band Using the Display BacklightFm Page 35 Wednesday, August 4, 1999 1049 AM Guide to Frequencies General Scanning GuideNational Weather Frequencies Ham Radio FrequenciesGuide to the Action Bands Birdie FrequenciesUnited States Broadcast Bands Primary Usage Typical Band UsageSpecified Intervals UHF Band Activities Frequencies MHzFrequency Ranges Specified Interval Band Allocation Abbreviations ServicesMeter Amateur Band 28.0-29.7 MHz High Frequency HF Hi 3 MHz-30 MHzGovernment Band 138-144 MHz Meter Amateur Band 50-54 MHzMeter Amateur Band 144-148 MHz VHF-Hi Band 148-174 MHzGovernment Band 406-450 MHz Coast GuardGOVT, Usxx Cm Amateur Band 420-450 MHzBUS, IND Avoiding Image Frequencies Frequency Conversion Error TroubleshootingAdjust Squelch Resetting the Scanner RESETTING/INITIALIZING the ScannerInitializing the Scanner Care and Maintenance Specifications +9 V DC, 6 AA batteries Fm Page 54 Wednesday, August 4, 1999 1049 AM Fm Page 55 Wednesday, August 4, 1999 1049 AM Sibility of Such Damages Limited One-Year Warranty

PRO-70 specifications

The Radio Shack PRO-70 is a compact and versatile handheld scanner that caters to both novice enthusiasts and seasoned hobbyists. Launched in the early 1990s, the PRO-70 exemplifies the functionality and accessibility that users seek in a portable scanning device. Its design is lightweight and ergonomic, allowing for easy handling during extended use, whether at home or on the go.

One of the standout features of the PRO-70 is its ability to scan multiple frequency ranges. Operating on VHF, UHF, and other bands, it covers a comprehensive spectrum that includes public safety, amateur radio, and various commercial communications. This wide frequency range empowers users to stay informed about local news, events, and emergency situations.

The scanner boasts a powerful memory bank, often allowing users to store over 100 channels, which can be easily programmed and accessed. The inclusion of priority channels enables users to monitor essential frequencies while still scanning other channels, ensuring that important communications are never missed. The programmable scan feature is particularly beneficial, allowing enthusiasts to customize their scanning experience according to personal interests or needs.

In terms of technology, the PRO-70 utilizes advanced digital signal processing to enhance audio clarity and reception quality. This feature enables users to receive crisp and clear transmissions, particularly in areas with weaker signals. Additionally, the scanner incorporates a durable and long-lasting rechargeable battery, providing extended use without the frequent need for battery replacement, which is an essential consideration for avid users.

The user interface of the PRO-70 is designed for ease of use, with an intuitive layout of buttons and a simple LCD display that presents critical information clearly. Users can easily navigate through channels, adjust volume levels, and set scanning parameters without a steep learning curve.

Overall, the Radio Shack PRO-70 represents a significant entry in the world of handheld scanners, marrying practicality with technology. Its robust features, combined with the flexibility of frequency coverage, make it an ideal choice for both casual listeners and serious scanning enthusiasts. The scanner’s reliability, affordability, and ease of use solidify its reputation as a valuable tool for anyone looking to connect with their community and beyond through the world of radio communications.