trying to make 27mhz AM Reciever with one crystal, help?

[nemoskull]

hi and welcome.
i am trying to make a 27mhz AM reciever, but i dont know much about AC or RF circuits. i have figured out that i need a filter to get only the frequency i need. i have a transmitter on 27.145 Mhz and have a 27.145 Mhz crystal and a non function RX board, ( i think the decoder chip is dead). i do okay with simple circuits, but i am more of a programmer than anything else.
i am trying to make this circuit becase of funding problems (none) and space limitations ( the rx board i have is too big)
any help anyone?

 

[Nigel Goodwin]

Considering the tiny size of commercial RC receivers, you're not going to build one anywhere near that small.

They are cheap to buy, and absolutely tiny - it would cost much more to try and make one.

 

[Dragon Tamer]

So you want the 27MHz crystal to receive an AM radio wave at 27MHz? Is this to receive an audio signal? If so your frequency is too high. The AM audio band covers about 560kHz to 1.4MHz.

You are right though, you do need a filter for the frequency you are trying to receive. You may also need an amplifier of some kind to boost the very small signal that will be coming out of your filter. I have never seen an RX board that used a crystal to receive the frequency. Usually they have a tuned LC or RC band pass filter. If your carrier frequency is 27MHz, then you may be able to use a crystal to filter out the carrier frequency.

 

[Nigel Goodwin]

So you want the 27MHz crystal to receive an AM radio wave at 27MHz? Is this to receive an audio signal? If so your frequency is too high. The AM audio band covers about 560kHz to 1.4MHz.

You are right though, you do need a filter for the frequency you are trying to receive. You may also need an amplifier of some kind to boost the very small signal that will be coming out of your filter. I have never seen an RX board that used a crystal to receive the frequency. Usually they have a tuned LC or RC band pass filter. If your carrier frequency is 27MHz, then you may be able to use a crystal to filter out the carrier frequency.

Sorry, but you seem to know little about radio, and even less about RC

RC uses crystal control for accuracy, and so you can have a number of models working at the same time. The crystal is used in the local oscillator in the superhet receiver - it's a standard radio circuit, with the local oscillator crystal based instead of variable.

 

[crutschow]

So you want the 27MHz crystal to receive an AM radio wave at 27MHz? Is this to receive an audio signal? If so your frequency is too high. The AM audio band covers about 560kHz to 1.4MHz.

AM (Amplitude Modulation) is used to broadcast audio on many more bands than just standard commercial broadcast. Short Wave, Citizen Band, and Amateur Radio bands are some examples.

 

[Dragon Tamer]

Sorry, but you seem to know little about radio, and even less about RC

Oh yes, it makes me wonder why I try sometimes... oh well. Besides I have only made a hand full of radio circuits that actually work, including a crystal AM receiver, a crude AM transmitter and a slightly better AM transmitter, with an even better one being made (I'm so excited!). I've made plenty of things that work with radios, but that's about it.

 

[nemoskull]

sorry, was not clear...

sorry, let me clarifiy. i dont know much about Rf circuits. as for buying a 27mhz RX, i have yet to find one that works. i am trying to send a signal to a RX that will simply give a HI voltage. ( say 5 volts POS). i am using AT tiny25's for encoding and decoding. i have a transmitter with a busted encoder chip, and can get a RX on the same frequency to give a voltage jump from 2v to 4 volts ( more or less), but the board is almost 1.75 inches square. i need a narrower board, and as long as it is less that 6 inchs, i am okay. AM is because that is what the transmitter is, and i need to avoid making my own transmitter (FCC). i am not using this for voice, just need to send a singal anp was going to use ASK for simple communication.
i was hoping to use a crystal to avoid using inductors coils, as i have no way of verifiying the milliHenerys. Buying them is out of the question, this is alos something of a challenge for me.
thanks
nemo