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Air-band receiver (IF amplifier selection)

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petrv

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Hi All,

I am thinking about building a receiver for the air-band (it should be fun to listen to the pilots talking :)

I have found a few designs on the net but they are either too simple (in fact little better than crystal radios) or they could work but use obsolete components, for example:

**broken link removed**

(MC1350 is obsolete and I don't like to have to use IF transfomers ...)

Probably more like this one:

Super improved AM-Receiver for Aircraft.

but even this one uses obsolete components. I can replace the PLL and mixers (e.g. LMX2306 and SA602 as I have them and they are still in production) but what about the IF amplifier ?

I am not sure which IC to choose for the IF amplifier with AGC. Perhaps I could use a VGA but it seems to me as an overkill (but I plan to try LMH6502 anyway)

I am thinking as a starting point to modify a kit which I own - 2m Ham radio receiver - I'll need to retune the input bandpass filter to the airband and also the 1st VCO - it is a dual-conversion FM receiver based on MC3362P, but still
it is a narrowband FM receiver and I need AM so I need to add another IF amplifier and again, what could be a good IC for this task ? (I do have a few TCA440 (AM receiver IC) which seems to be suitable for the task but it is again an obsolete chip).

Another thing I am not sure is the 1st IF of 10.7 MHz which may be too low to suppress image reception if I want to cover all the air-band. The other possibility is to use a crystal filter (21.4 or 45 MHz - I have 45 MHz xtal filters) but from what I have heard xtal filters are tricky components and require good impedance matching ...

I'd be glad to hear your suggestions on this problem.

Thanks,

Petr
 
Hi All,

I am thinking about building a receiver for the air-band (it should be fun to listen to the pilots talking :)

I have found a few designs on the net but they are either too simple (in fact little better than crystal radios) or they could work but use obsolete components, for example:

**broken link removed**

(MC1350 is obsolete and I don't like to have to use IF transfomers ...)

Probably more like this one:

Super improved AM-Receiver for Aircraft.

but even this one uses obsolete components. I can replace the PLL and mixers (e.g. LMX2306 and SA602 as I have them and they are still in production) but what about the IF amplifier ?

I am not sure which IC to choose for the IF amplifier with AGC. Perhaps I could use a VGA but it seems to me as an overkill (but I plan to try LMH6502 anyway)

I am thinking as a starting point to modify a kit which I own - 2m Ham radio receiver - I'll need to retune the input bandpass filter to the airband and also the 1st VCO - it is a dual-conversion FM receiver based on MC3362P, but still
it is a narrowband FM receiver and I need AM so I need to add another IF amplifier and again, what could be a good IC for this task ? (I do have a few TCA440 (AM receiver IC) which seems to be suitable for the task but it is again an obsolete chip).

Another thing I am not sure is the 1st IF of 10.7 MHz which may be too low to suppress image reception if I want to cover all the air-band. The other possibility is to use a crystal filter (21.4 or 45 MHz - I have 45 MHz xtal filters) but from what I have heard xtal filters are tricky components and require good impedance matching ...

I'd be glad to hear your suggestions on this problem.

Thanks,

Petr
I think you should stay with the SA602 as mixer, and a MC1350 for the IF. With passive band pass filter on the input to the SA602 mixer the 10.7Mhz if should be fine with out worry of an image problem. I have in my personal stock a few MC1350 ic's, I would be happy to send you a couple. PM me about them
 
Hi All,

I am thinking about building a receiver for the air-band (it should be fun to listen to the pilots talking :)

,,,,,,,,,,,,,,,,,,,,,, (I do have a few TCA440 (AM receiver IC) which seems to be suitable for the task but it is again an obsolete chip).

Another thing I am not sure is the 1st IF of 10.7 MHz which may be too low to suppress image reception if I want to cover all the air-band. The other possibility is to use a crystal filter (21.4 or 45 MHz - I have 45 MHz xtal filters) but from what I have heard xtal filters are tricky components and require good impedance matching ...

I'd be glad to hear your suggestions on this problem.

Thanks,

Petr

Hay, You are one of few lucky people still having TCA440

It is just useful for aircraft band Rx.
I have an Elektor magazine design in PDF. It is exactly to what components you have . the same is attached for ready ref.
 
Last edited:
Thanks much for the article,

it is very useful as a reference and yes I still have 3 pcs of TCA440 (and also a few MC1350, this is not a problem - if you are looking for TCA440 maybe try to write to Barend Hendriksen in Netherlands I think maybe can have some).

The point is I don't want just build something, I want to design a new one with PLL digital tuning (with LMX2306 PLL and a PIC MCU) and I really do not want to use obsolete ICs like MC1350 or TCA440. That is why I have asked for ideas about IF amplifier. Also I'd prefer a design that does not use too many inductors, especially variable (tunable) and RF/IF transformers. I prefer to use capacitive coupling and
ceramic filters for selectivity (instead of tuned LC).

Petr
 
Thanks much for the article,

it is very useful as a reference and yes I still have 3 pcs of TCA440 (and also a few MC1350, this is not a problem - if you are looking for TCA440 maybe try to write to Barend Hendriksen in Netherlands I think maybe can have some).

The point is I don't want just build something, I want to design a new one with PLL digital tuning (with LMX2306 PLL and a PIC MCU) and I really do not want to use obsolete ICs like MC1350 or TCA440. That is why I have asked for ideas about IF amplifier. Also I'd prefer a design that does not use too many inductors, especially variable (tunable) and RF/IF transformers. I prefer to use capacitive coupling and
ceramic filters for selectivity (instead of tuned LC).
Petr
Thanks for the reply. I saw the availability of TCA440 with M/s Barend Hendriksen. Unfortunately they would become too costly as we import few chips on international scenario, due to non EU area where I live in and the couriers add more. Perhaps I may have to search for local availability.

As regards your design, you may consider resorting to I-Q mixer principle as used in Software defined Radios. Oflate there is one by Burkhard Kainka, published in may2007 issue of Elektor UK. you may adopt DDS for the LO. The controller would give digital display of the tuned frequency. Finally you may have to depend on your laptop for the resultant audio with software srdradio ver1.0 from **broken link removed**
 
Hi,
I don't think it would be that expensive. Barend (thought his prices are not low) can ship by post which will cost a few Euro worldwide (for small shipments like a few TCA440) and you can pay by PayPal to avoid high international bank transfer fees.

And, using SDR for a simple AM receiver would be certainly an overkill ... I guess I'll have to experiment a bit. I have SA602s, both ceramic filters and 45 MHz crystal filter (from rfcandy.com) and the IF part ... I'll try something to see how it will (or will not) work.

Petr
 
Hi,
I don't think it would be that expensive. Barend (thought his prices are not low) can ship by post which will cost a few Euro worldwide (for small shipments like a few TCA440) and you can pay by PayPal to avoid high international bank transfer fees.

And, using SDR for a simple AM receiver would be certainly an overkill ... I guess I'll have to experiment a bit. I have SA602s, both ceramic filters and 45 MHz crystal filter (from rfcandy.com) and the IF part ... I'll try something to see how it will (or will not) work.

Petr
Thanks
Wish you all the best in your aircraft-band project.
 
Thanks Sarma,
yes I am working on it, I'll let you know if I find out something useful. Right now I am hacking a 2m receiver (FM)... I have retuned the VCO and reprogrammed the PLL so it tunes to the correct frequencies, now just need to adjust the input bandpass filter and then try some external IF amplifiers (the built-in is FM so it is not useful ...).
Petr
 
Hi,

I am an Electronics engineering student and very interested in aviation, and always wanted to build my own airband RX, which I want to build for a assignment at university. After googling I found this link to the site and I am interested in how you got on with this project.

Thanks haydn
 
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