Is it possible to modify a multi-band radio to receive LW and AIR?

Thread Starter

bypassrestrictions

Joined Jun 1, 2021
94
I have a multi-band radio, which receives MW, FM, SW with some TV frequencies.

Is it possible to modify this radio to receive LW and AIR? Will it be as simple as winding more copper wire around ferrite bar and changing the variable capacitor or do I need to change any ICs?

It is an analogue radio, I haven't opened it, I can open it and post photos if anyone here can suggest changing variable capacitor or winding more copper wire.
 

vu2nan

Joined Sep 11, 2014
232
Thank you for the information.

Altering the radio's 88 - 108 MHz FM band, to receive the Air Band, would be quite easy.

All you would need to do is spread the antenna and oscillator coils. However, the audio quality may not be too good while receiving AM on an FM radio.

Altering the MW band to receive LW would involve increasing the number of turns on the ferrite rod antenna and replacing the MW oscillator coil. Modifying it for LW would be quite difficult, considering its size and the thin gauge of wire that has been used.

The better option would be to build an 'up' converter for LW and a 'down' converter for the Air Band and tuning-in to their output on a good AM receiver.
 
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Thread Starter

bypassrestrictions

Joined Jun 1, 2021
94
Thank you for the information.

Altering the radio's 88 - 108 MHz FM band, to receive the Air Band, would be quite easy.

All you would need to do is spread the antenna and oscillator coils. However, the audio quality may not be too good while receiving AM on an FM radio.

Altering the MW band to receive LW would involve increasing the number of turns on the ferrite rod antenna and replacing the MW oscillator coil. Modifying it for LW would be quite difficult, considering its size and the thin gauge of wire that has been used.

The better option would be to build an 'up' converter for LW and a 'down' converter for the Air Band and tuning-in to their output on a good AM receiver.
How would I up-convert and down-convert?
 

BobTPH

Joined Jun 5, 2013
4,897
To tune 108 to 128 you would mix the input with a local oscillator of 20 MHz. This would convert it to the FM band of 88 to 108 because mixing produces a signal at the difference.

It also produces a signal at the sum. If you want to tune below the AM band, mix with something if the range of 1 MHz.

Bob
 

Audioguru again

Joined Oct 21, 2019
4,675
Most FM radios have excellent AM rejection and have de-emphasis. Then tuning an FM radio to the higher AM AIR frequencies will not work. Many years ago I made a regen radio that picked up AIR transmissions.
 

Audioguru again

Joined Oct 21, 2019
4,675
Most FM radios have excellent AM rejection and have de-emphasis. Then tuning an FM radio to the higher AM AIR frequencies will not work. Many years ago I made a regen radio that picked up AIR transmissions.
 

Thread Starter

bypassrestrictions

Joined Jun 1, 2021
94
To tune 108 to 128 you would mix the input with a local oscillator of 20 MHz. This would convert it to the FM band of 88 to 108 because mixing produces a signal at the difference.

It also produces a signal at the sum. If you want to tune below the AM band, mix with something if the range of 1 MHz.

Bob
The radio is able to tune up to 230MHz because it covers TV bands. Is it necessary to add a local oscillator, if it goes 230MHz, it might already cover AIR band.
 

Dodgydave

Joined Jun 22, 2012
10,302
What is the make and model number of the radio?

To increase the frequency band the tuning capacitor needs less capacitance and the tuning coils need to be lowered.
 

vu2nan

Joined Sep 11, 2014
232
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