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Radio receiver question ...?

时间:04-07 整理:3721RD 点击:
What radio receivers contains intermediate frequency transformers?

If the receiver employees IF section then it should have an IF transformer.

As far As I Know, All modern broadcast band receiver has an IF stage ( AM or FM ) and they have IFT( Intermediate Frequency Transformer).

Of-course they are separate.

Lastly Any Super heterodyne receiver has IF stage and have IFTs.

Guess this much you wanted.

bluehole has it about right, other then modern superhets actually use a ceramic filter to provide the selectivity.
Frank

That's the principal purpose of an i.f. transformer. Impedance matching (with a transformer) is really a secondary consideration, but the name has stuck.

Hi, Medium wave and short wave bands will have intermediate frequency stages scince due large bandwidth/frequecny range. the RF amplifier gain is not equal for all receiving radio chanels at different frequencies due to passive components. so what ever the desired frequency we are receiving we first convert it into IF frequency (intermediate frequency-455KHz) and then amplify through RF amplifier to required strenth which is tuned for 455KHz. the following is the stages of a radio receiver for clarity

1)RF stage consists of oscillator and IF transformers for channel selection and convertion to intermediate frequency 455KHz.
2)RF amplifier for amplification, desined and tuned for 455KHz.
3)demodulator.
4)audio amplifier.
5)speaker.

Some radios have two, and even three, i.f's.

One receiver with which I was familiar covered a frequency range of 15kHz to 28MHz and had a first i.f. of 700kHz and a second i.f. of 85kHz.

The Racal TRA-931 transceiver, 1.4MHz to 29.999MHz, had a first i.f. of 35.4MHz and a second i.f of 1.4MHz.

The Racal RA-17 receiver, 980kHz to 30MHz, had a first i.f. of 40MHz, a second i.f. of 2.5MHz and a third i.f. of 100kHz.

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