Tda 7000 receiver

[admin2far]

Hi
i wanted to ask if i use 1uh coil and 10-20 pf capacitor in legs 5,6,
whould i receive the 35-50 mhz band?
in leg 13 there is only 180pf capacitor and antenna,no coil.
thank you.

 

[Russlk]

Probably not, because the TDA7000 is a superhet receiver. The oscillator frequency has to be offset by the amount of the IF frequency.

 

[admin2far]

o.k.
so,can someone tell me how i can receive these frequencies?
(30hmz-50mhz)
thanks

 

[Nigel Goodwin]

o.k.
so,can someone tell me how i can receive these frequencies?
(30hmz-50mhz)
thanks

What are you trying to receive?, as far as I'm aware the TDA7000 is a WBFM (Wide Band FM) receiver chip - and I don't think there are any WBFM signals in that frequency range.

 

[admin2far]

I am trying to receive mobile phone frecuencies,i try to create aother phone unit in my home.

 

[Nigel Goodwin]

I am trying to receive mobile phone frecuencies,i try to create aother phone unit in my home.

Aren't your mobile phones digital?.

But I don't think even the old analogue mobiles were the sort of things that you could use a TDA7000 for?.

 

[admin2far]

I don't talk on cellular phones,i am talking about the phones that there frequencies are 40 to 49 mhz in 30khz steps

 

[Nigel Goodwin]

I don't talk on cellular phones,i am talking about the phones that there frequencies are 40 to 49 mhz in 30khz steps

Right! - not 'mobile' phones, but 'cordless' phones, ones which use a normal land line.

All the recent ones of those I've seen have been digital as well, but the older ones (in the UK) used a low frequency (top end of MW band) link from base station to handset, with a shortwave link back from handset to base station - certainly 40-49MHz sounds the right sort of frequency.

Assuming the links are FM, they will be narrow band (the frequency used suggests that, and the bandwidth confirms it). The TDA7000 is designed as a wideband broadcast receiver, I can't say I've studied the TDA7000 much, but the usual way of doing narrow band is to use a lower IF frequency, 455KHz instead of 10.7MHz. Most often this is done using a dual-conversion technique.

 

[admin2far]

yes you right,cordless' phones,sorry.
i know there is a way making the tda7000 receive narrow band:
**broken link removed**
do you know more simple way?

 

[Nigel Goodwin]

yes you right,cordless' phones,sorry.
i know there is a way making the tda7000 receive narrow band:
**broken link removed**
do you know more simple way?

No, because it's only single conversion you need good front end tuning, the application note looks to be exactly what you want!.

This is why 10.7MHz is usually used for an FM IF, it means your image frequency is 21.4MHz away, which reduces your front end tuning considerably.