How to convert frequencies

Hello,

I'm a complete electronics novice but would like to get involved at a basic level. As a project I'd like to receive a radio frequency, convert it, and then transmit it on to my radio receiver. Sort of like a proxy I suppose.

After some basic research I think I need the following:

Antennae to receive RF RF mixer to filter the frequencies Oscillator to pass in the desired frequency to the RF mixer Low pass filter to filter out the unwanted frequencies Amplifier Transmitter

And some sort of circuit board to put it all together. I'm curious how home brew electronics work with regards to circuit boards. I'd like the device to be as compact as possible, but don't mind if the prototype is a huge monstrosity.

I'll have a look around a bit further myself, but wondered if you had any pointers that might save me time and sanity.

Cheers,

Gordy

Reply to
gordon.is.a.moron
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ic level. As a project I'd like to receive a radio frequency, convert it, a= nd then transmit it on to my radio receiver. Sort of like a proxy I suppose= .

me brew electronics work with regards to circuit boards. I'd like the devic= e to be as compact as possible, but don't mind if the prototype is a huge m= onstrosity.

pointers that might save me time and sanity.

Hmm, maybe just start with building a radio reciever. I'm sure there are lots of designs on the web. A little AM reciever is pretty easy. (Read low frequency). If you continue interest then find out if there is a local HAM group in your area. There may be some pepole there that can help. Oh, and pick up a copy of the ARRL handbook. Lots of practical advice and circuits.

George H.

Reply to
George Herold

ic level. As a project I'd like to receive a radio frequency, convert it, a= nd then transmit it on to my radio receiver. Sort of like a proxy I suppose= .

me brew electronics work with regards to circuit boards. I'd like the devic= e to be as compact as possible, but don't mind if the prototype is a huge m= onstrosity.=20

pointers that might save me time and sanity.

I would agree with the suggestion that you start looking for a basic receiv= er design to start with - but would say that even that's a bit of a stretch= if you are a "complete electronics novice."

What you are trying to do IS basically what's called a "superheterodyne" re= ceiver, which describes the vast majority of radio receivers out there toda= y anyway. The hallmark of a "superhet" design is that it converts all inco= ming frequencies to a common "intermediate frequency" which is then amplifi= ed and demodulated. Getting a copy of a good basic text on radio - the ARR= L Radio Amateur's Handbook" might be a good place to start - would be a gre= at start in the right direction. (It's really too bad that the good ol' cl= assic Heathkits are no longer available. However, there are still some bas= ic receiver kits available to get started with, like:

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(not a superhet,= but could be fun))

One minor gotcha in building a superhet is that this type of receiver requi= res an adjustment process ("alignment") to get everything working properly = together - it's not impossibly difficult, but again may be a bit much for t= he real novice to pull off, especially without some test equipment.

Bob M.

Reply to
Bob Myers

Then start with the basics and give the details. Why not just buy a receiver that tunes the frequency? What is the frequency? Is this for the sake of building something, or to get some end results?

Michael

Reply to
Michael Black

Essential terminology:

You want to receive a radio _signal_ at a particular _frequency_, shift the frequency, and retransmit.

RF mixers shift signal frequencies. Filters filter signals (generally within some band of frequencies)

Oscillator to pass the desired frequency _difference_ to the mixer.

Or some sort of filter -- probably bandpass.

An amplifier is part of a transmitter -- stick an antenna on the end of yours, and you're done.

If you're broadcasting within your house, then just sticking an antenna on the end of your post-mixer filter may well be enough.

AM? FM? Regular broadcast frequencies or something more out of the way, like FRS, CB, or shortwave?

Buy a receiver that works on the band that you want -- one from Goodwill or a rummage sale should be fine. Buy a transmitter kit that works on the band that you want. Feed audio from the receiver to the transmitter. Stand back and enjoy (well, stand back and debug).

Then, when you get that working, you may know enough to go on to some other step.

Ramsey Electronics has kits for you. There is, to my knowledge, no real Gold Standard in electronics kits since the demise of Heathkit -- but Ramsey sells some pretty good brass.

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Reply to
Tim Wescott

I didn't want this answer to get lost in my other reply: what you're thinking of building is a repeater or a translator (depending on who you ask). If you want to look for a kit or on-line schematics, those are the search terms to use.

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Reply to
Tim Wescott

level. As a project I'd like to receive a radio frequency, convert it, and then transmit it on to my radio receiver. Sort of like a proxy I suppose.

brew electronics work with regards to circuit boards. I'd like the device to be as compact as possible, but don't mind if the prototype is a huge monstrosity.

pointers that might save me time and sanity.

What frequency do you want to receive, and what frequency do you want to convert it to?

A simple oscillator and mixer - potentially very simple - can do the basic function, if you don't mind receiving image frequencies and such. It would be a good place to start.

--
John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
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Reply to
John Larkin

I'm not sure that is what he wants. I read the "transmit to a receiver" as "feed the mixer into the receiver". But since he hasnt' actually said what he wants, just trying to interpret based on a little knowledge, it certianly isnt' clear.

Michael

Reply to
Michael Black

level. As a project I'd like to receive a radio frequency, convert it, and then transmit it on to my radio receiver. Sort of like a proxy I suppose.

brew electronics work with regards to circuit boards. I'd like the device to be as compact as possible, but don't mind if the prototype is a huge monstrosity.

pointers that might save me time and sanity.

--
A simplistic version of what you're asking for, assuming that you're
only interested in dealing with a single input frequency, would
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Reply to
John Fields

Hmm. That hadn't occurred to me, because I unconsciously put "through free space" after "transmit" (or maybe "receiver").

If he just wants to modify a receiver to work in a different band that originally designed, he wants a converter. He can google for those, too, but he'll get a lot of downconverters, and not a lot of old-style ham radio converters (if that is, indeed, what he wants).

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Reply to
Tim Wescott

sic level. As a project I'd like to receive a radio frequency, convert it, = and then transmit it on to my radio receiver. Sort of like a proxy I suppos= e.

ome brew electronics work with regards to circuit boards. I'd like the devi= ce to be as compact as possible, but don't mind if the prototype is a huge = monstrosity.=20

y pointers that might save me time and sanity.

Thanks everyone. What I'm trying to do is receive a UMTS signal from a mobi= le phone network and then drop the frequency so my phone can receive it. Th= e revision of the phone is set up for GSM and can only do one frequency of = the UMTS pair that the network uses. I thought it would be an interesting i= dea, though how attainable it is I don't know.

Anyway, the idea is receive the UMTS signal, drop it by 50mhz and then tran= smit it to my phone. Hopefully I can receive the signal an pass it on witho= ut having to authenticate the receiver in any way, such as registering an I= MEI or something.

Cheers, Gordy

Reply to
gordon.is.a.moron
** What a good name.

Thanks everyone. What I'm trying to do is receive a UMTS signal from a mobile phone network and then drop the frequency so my phone can receive it. The revision of the phone is set up for GSM and can only do one frequency of the UMTS pair that the network uses. I thought it would be an interesting idea, though how attainable it is I don't know.

Anyway, the idea is receive the UMTS signal, drop it by 50mhz and then transmit it to my phone. Hopefully I can receive the signal an pass it on without having to authenticate the receiver in any way, such as registering an IMEI or something.

** Got news for you - f****it.

A mobile phone is a TRANSCEIVER !

It is not a radio - it cannot be a receiver alone.

..... Phi

Reply to
Phil Allison

a mobile phone network and then drop the frequency so my phone can

probably not going to work.

supposing your phone can see and understand the cell station, the first thing it's going to try to do is register. and that's not going to work without a transmit path.

I non't even know if UMTS and GSM are compatible enough that the phone will even see the cell station, given that the data rates are so different, I doubt that it will.

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Reply to
Jasen Betts

basic level. As a project I'd like to receive a radio frequency, convert it= , and then transmit it on to my radio receiver. Sort of like a proxy I supp= ose.

home brew electronics work with regards to circuit boards. I'd like the de= vice to be as compact as possible, but don't mind if the prototype is a hug= e monstrosity.

any pointers that might save me time and sanity.

bile phone network and then drop the frequency so my phone can receive it. = The revision of the phone is set up for GSM and can only do one frequency o= f the UMTS pair that the network uses. I thought it would be an interesting= idea, though how attainable it is I don't know.

ansmit it to my phone. Hopefully I can receive the signal an pass it on wit= hout having to authenticate the receiver in any way, such as registering an= IMEI or something.

Ah, that sounds hard! and possibly illegal. Why not just buy a new cell phone?

George H.

Reply to
George Herold

(Newbie note: we all learn to ignore Phil when he's off his meds. This is USENET; there's some whackos -- and, well. Anyway)

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Reply to
Tim Wescott

asic level. As a project I'd like to receive a radio frequency, convert it,= and then transmit it on to my radio receiver. Sort of like a proxy I suppo= se.

home brew electronics work with regards to circuit boards. I'd like the dev= ice to be as compact as possible, but don't mind if the prototype is a huge= monstrosity.

ny pointers that might save me time and sanity.

iver design to start with - but would say that even that's a bit of a stret= ch if you are a "complete electronics novice."

receiver, which describes the vast majority of radio receivers out there to= day anyway. =A0The hallmark of a "superhet" design is that it converts all = incoming frequencies to a common "intermediate frequency" which is then amp= lified and demodulated. =A0Getting a copy of a good basic text on radio - t= he ARRL Radio Amateur's Handbook" might be a good place to start - would be= a great start in the right direction. =A0(It's really too bad that the goo= d ol' classic Heathkits are no longer available. =A0However, there are stil= l some basic receiver kits available to get started with, like:

, but could be fun))

uires an adjustment process ("alignment") to get everything working properl= y together - it's not impossibly difficult, but again may be a bit much for= the real novice to pull off, especially without some test equipment.

Yes, it requires quite a few repeated adjustments to get everything right. I managed to make an AM broadcast superhet using the NE602 balanced modulator, and there are several adjustments to be repeated to get things right. I learned how to do it working in a radio factory for 6 months.

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-Bill

Reply to
Bill Bowden

As mentioned, there's a lot more going on between UMTS and GSM than just the frequency difference. It probably can't be done in any way that's simpler than building a phone and a base and hooking them up.

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Reply to
Tim Wescott

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=20

Ah ok, not that surprising then. I thought it would be an interesting idea.= Oh by the way, it doesn't involve converting GSM to UMTS or GSM at all - I= t's UMTS all the way, what I meant to say was the phone was GSM biased in t= hat it supported GSM networks better than UMTS. But yes, sounds impractical= really. I thought it would be an interesting project. Oh well, thanks ever= yone.

Cheers,

Gordy.

Reply to
Ian Wiles

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