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#### Theresetbutton

##### New Member
Hey people, I have a thorny problem. I've been trying to find out how I would go about making an AM receiver that will tune into exactly 17.017ghz (it shouldnt be used, and yes, I know its probably not legal) and nothing else.

should I be using an MMIC, or PLL tuner? can of the shelf parts go that high? range is stupidly low, I know, so no need to tell me about an antennas.

some feedback would be nice. even if its what the hell are you doing

#### tcmtech

##### Banned
So whats there at 17.017 GHz that needs listening to?

#### Theresetbutton

##### New Member
not really 100%. the person who ask me about this hasnt exactly explained what it is. considering who he is, its something about about the occult. I dont ask too many questions. even still, I said I'ld ask around. its only am radio, not data transmision or anything. can it be done at all?

#### crutschow

##### Well-Known Member
Doubt that you will find anything off the shelf at the frequency that isn't quite costly.

#### tcmtech

##### Banned
Is 17.017 Ghz the natural resonace frequency of nut jobs? Or is that the curse and hexing frequency?

#### Theresetbutton

##### New Member
Doubt that you will find anything off the shelf at the frequency that isn't quite costly.
can you multiply a base frequency? I dont know how clock generators work, or if its a valid thing for a radio receiver? does anyone know?

#### dknguyen

##### Well-Known Member
can you multiply a base frequency? I dont know how clock generators work, or if its a valid thing for a radio receiver? does anyone know?
Yes you can. It's called a PLL, but (I think, not sure) it only works for square waves...and maybe sawtooth, but not sine-waves.

psttt. tcmtech, you have a spelling error in your sig.

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#### Theresetbutton

##### New Member
Yes you can. It's called a PLL, but (I think, not sure) it only works for square waves...and maybe sawtooth, but not sine-waves.

psttt. tcmtech, you have a spelling error in your sig.
so, its useless for audio? I think a few radios out there use PLL for their standard tuners (browsing around the net for an answer, kinda came across that...)

ok.... so, using PLL, I can tune to that frequency? I was thinking about something this simple:

of course, I would receive instead. BUT I was having problems with finding something to tune that high. if you could find out a little more, that would be awesome

#### Nigel Goodwin

##### Super Moderator
You simply downconvert it to a more sensible frequency, and use a normal AM communication receiver to listen to it.

However, a 17GHz down-converter isn't going to be a simple job.

#### Mikebits

##### Well-Known Member
psttt. tcmtech, you have a spelling error in your sig.
Where, aside from a missing apostrophe or two, I don't see one?

#### dknguyen

##### Well-Known Member
Where, aside from a missing apostrophe or two, I don't see one?
*You're. More than just an apostrophe.

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#### Mikebits

##### Well-Known Member
*You're. More than just an apostrophe.
Now that is just picking nits. You should have said improper usage of a contraction rather than a spelling error.

BTW, you missed it's.

Now go and have a beverage

#### Papabravo

##### Well-Known Member
It's hard to imagine what you think you will hear at that frequency, but there is nothing illegal about building a receiver that I know of.

At such frequencies the propagation is usually so poor that you have to wait for a really dry day, and use parabolic dish antennas aimed with a rifle scopes to get a useable signal at more than a mile or so.

If you were successful in constructing such a receiver it is doubtful you would hear anything coming through and you would quickly become bored with the whole affair.

My cost estimate for this receiver would be about $7000 -$ 10,000 including the research, fabrication of the components, and purchase of the required parts. It would look like an antenna, a down converter, and a purchased general coverage receiver like an R-2000 which goes up to about 2 GHz.

#### Nigel Goodwin

##### Super Moderator
It's hard to imagine what you think you will hear at that frequency, but there is nothing illegal about building a receiver that I know of.
If you're bothered googling it, you wouldn't be lacking in imagination

Plenty of hits on 17Ghz

#### Papabravo

##### Well-Known Member
I think you've crossed the line Nigel. What's up with the attitude pal?

#### tcmtech

##### Banned
Being a non RF circuitry person I have to ask is there a easy or reasonably simple circuit for down converting signals in the GHz ranges to something lower?

#### crutschow

##### Well-Known Member
Being a non RF circuitry person I have to ask is there a easy or reasonably simple circuit for down converting signals in the GHz ranges to something lower?
Not if you also want it cheap.

#### tcmtech

##### Banned
I would just be happy with a working schematic. Cheap is in the eye of the beholder!

#### BrownOut

##### Banned
The math for downconverting would be very similar to the discussion we had about AM modulation. If you had two signals, and your circuit had a component of gain that was a X^2:

(cosA + cosB)^2 = 1/2(cos (A + B) + cos(A - B)) + rejected terms

So you end up with a sum and difference of frequencies. You simply reject the sum and end up with the 'downconverted' signal. So, if you find a downconvertor, you can work out the frequency to feed it with to get the desired signal. The trick is to make it work in the GHZ range. Not impossible, but you get into a whole new set of issues.

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