1973 Lafayette Gaurdian 7000 multiband radio question..

Gaurdian7000

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I'm new to this site so I hope I'm in the correct place. I have a Lafayette Guardian 7000 multiband radio from 1973. I got it when I was 17. Amazingly, it still plays like new. Its been in daily heavy service since 1973.

I have a UHF band question, it covers from 450mhz to 470mhz. I used to be able to listen to the local police which broadcasts at frequency 471.5125 which is higher than the band on my radio, but somehow I received it for years. Now there's nothing there...but they are at the same frequency. There used to be a repeater near my home. I think its gone. Would that have transmitted at a lower frequency allowing my ancient UHF band to still receive? I have another(slightly newer) radio that covers 450mzh to 512mhz it picks up the police fine. I'm just trying to understand what happened. Again I hope my post is in the right place.
 

chief21

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I have a UHF band question, it covers from 450mhz to 470mhz. I used to be able to listen to the local police which broadcasts at frequency 471.5125 which is higher than the band on my radio, but somehow I received it for years. Now there's nothing there...but they are at the same frequency.
I wouldn't be surprised that the tunable radios of that era could receive signals somewhat higher or lower than the specifications indicated. Tuneable circuits are not so precise. The 470 MHz public safety band has a 3 MHz separation, so the repeater would transmit at 471.xxxx and the mobiles would transmit at 473.xxxx.

It's not at all uncommon for agencies to upgrade their radio systems from time to time, so the repeater that used to be near you might well have been relocated. Another possibility... the radio system could have been upgraded to a simulcast system (with multiple transmitter sites). Some simulcast systems are difficult to receive due to receiving interference from related sites operating on the same exact frequency. Or perhaps your receiver is being overloaded by a nearby transmitter on a totally different frequency (or band, even) that your older radio is susceptible to.
 

Gaurdian7000

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I wouldn't be surprised that the tunable radios of that era could receive signals somewhat higher or lower than the specifications indicated. Tuneable circuits are not so precise. The 470 MHz public safety band has a 3 MHz separation, so the repeater would transmit at 471.xxxx and the mobiles would transmit at 473.xxxx.

It's not at all uncommon for agencies to upgrade their radio systems from time to time, so the repeater that used to be near you might well have been relocated. Another possibility... the radio system could have been upgraded to a simulcast system (with multiple transmitter sites). Some simulcast systems are difficult to receive due to receiving interference from related sites operating on the same exact frequency. Or perhaps your receiver is being overloaded by a nearby transmitter on a totally different frequency (or band, even) that your older radio is susceptible to.
Thank you for your response. I was thinking the same thing, as my old Lafayette radio still picks up other police stations in the area. I thought perhaps an antenna wire became un soldered, but on inspection all wires are attached. This radio is amazing for its age. Very sensitive.
 

a29zuk

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My brother bought the Lafayette Guardian 7700 around 1974 or 75. It also had AM, FM ,SW, VHF-Lo, VHF-Hi, and UHF(450-470mhz).
That radio was built like a tank. I enjoyed using it when I had a chance.

Jim
 

N8IAA

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Rookie mistake Guardian7000, can't answer your question without a location.

It could be a variety of reasons, narrow band, using a digital mode, or maybe even moved to a trunk system. Even changed frequencies.
 
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