Project or Book with 2 Watt VHF transmitter for tracking

Look for a Forest Mimms project fir exactly this application

ZipZapOuch said:

Look for a Forest Mimms project fir exactly this application

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Mims is too basic for transmitters over a watt.

preWarp said:

Mims is too basic for transmitters over a watt.

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Good luck.

This is one for the 144 MHz Amateur band, as a design example:

Note that in most of the world it is illegal to actually use any kind of DIY transmitter (and many commercial ones) without a specific licence, you cannot connect any such transmitter to an actual antenna - only a dummy load to absorb the power.

Without a licence, the power limits are typically in the microwatts to a milliwatt, depending on frequency and country. The penalties for ignoring the laws can be extreme..


Legal ready-made RF modules for DIY use are made to work within certain specific frequency bands and with specific power limits, and certified by the manufactures under "type approval" licence schemes or similar.

The only generally legal DIY way is to get an appropriate class of Amateur Radio licence, which ensure you know the frequency, power and interference regulations & allows you to build, test and use your own transmitters, within the appropriate bands.

(A fair number of the users of this site are licenced radio amateurs).

preWarp said:

Hello. Does anyone know of a project and design files online or otherwise a book with the designs and schematics for a VHF transmitter around 2 Watts in power? I would like to use it for to track model rockets. I am on this board because I am mostly interested in designs, not so much about the deep theories of operational amplifiers. My plan is actually to understand the circuit by building portions of it at a time and testing with an oscilloscope and lab power supply. Can't wait to find a design. I just don't know of a good book with circuits and designs. I didn't find any design files for CAD/CAM online so far.

Thanks

By the way I am very interested in learning. Not buying mass proliferated GPS or other convenance. I am interested in Printed Circuit Board design and manufacturing. So I am looking for plans to build a VHF transmitter, hopefully 2 watts or more. But I'm just learning so I am more interested in designs and my own experimenting. Sorry if you consider that to be low class. Not everyone is high class. Certainly not me.

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As has already been said, what you want is illegal in pretty well all countries, and could well have substantial penalties.

From what I recall the UK laws allow seriously substantial fines, and even jail time - depending on severity and how many offences you've committed.

I would suggest you contact other model rocket groups, and check what legal solutions are available.

Bear in mind, VHF is 'line of sight' - so a 2W transmitter on a high flying rocket will go a hell of along way.

I commonly used to work 100 miles just with a 1W handheld transmitter, simply by being on top of a modest hill.

Yes. I will use a legal frequency. I need more range than the circuits that use bjts. That's why I have not chosen one of the simpler designs that are available for beginners. This is about using a more complicated design to get a better range. I can learn to build the circuit using my equipment and working on portions at a time until I know the whole circuit. Just need the title of a book with circuits. Or otherwise an online design file for CAD/CAM. This is precisely why I am interested in a VHF radio with a transmission range over a mile. I want to manufacture the PCB. And then track my model rockets. Always wanted to do this. But I did not understand that tracking is done with VHF. By the way people that use GPS and other computer coordinates have to deal with other problems created by networking. I'm more interested in radio essentials. Thanks. Title of a book of circuits would be great. Design files for CAD/CAM also very interesting. But have not found either yet. I remember a great book about high frequency BJT circuits in the GHz range and an even better one using operational amplifiers. But they were less about building and more about learning mathematics.

preWarp said:

But they were less about building and more about learning mathematics.

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So, you want to start from the basics and not use any premade modules, you want to tune your circuit to insure you use only legal frequencies. You want to use 2watts or more, and you don't want to learn the math that supports such an endeavor.

The only path forward, and avoid the $10k/day fine, is to go to the Universal Studios store and buy a Harry Potter wand - then pray it works.

If you'd look into the math, the design of sensitive, well-tuned radio receivers with appropriate antennas and signal encoding methods, you'll realize that, you can use the Mimm's circuits (or any number of other AM, FM, FSK, ASK, PSK, (many more...) for ranges of 5-miles or more line-of-sight.

Again, good luck.

preWarp said:

I need more range than the circuits that use bjts.

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What?

preWarp said:

I will use a legal frequency.

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There is no such thing as a "Legal frequency" for transmitting from home built equipment at anything more than possibly microwatts without a licence!

preWarp said:

Title of a book of circuits would be great.

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The VHF / UHF Manual:

preWarp said:

I need more range than the circuits that use bjts.

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That is completely nonsensical.

I've worked the International space station using just a 2m (144-146MHz band, bipolar PA) 5W handheld with it's small helical antenna.
Trivial powers are needed for line-of site operation. Buildings, trees, hills & curvature of the earth etc. are the problems.

Many high-power VHF / UHF transmitters or amps use bipolar transistors.
eg. 40W and 60W rated devices:



Receiver noise figure, sensitivity and selectivity are just as - or more - important that transmit power. Gain can be at either end of a link to get the same signal-to-noise level.


Also, a "dumb" radio beacon and normal receiver will not allow you to track a fast moving object, or get any useful telemetry from it.

This is a good article on direction finding; the two antenna diode-switched system is a simple one that can give very good results:

Or, this is a rather more complex setup that gives a relative bearing - it's pretty much the same as used by police for tracking stolen vehicles equipped with a "Lojack" system.

All right. Fair enough. Thanks everyone for your help. I'll just try to work this some other angle. I need to check and make sure I've got founded ideas. Right now my thoughts need clarification. So I'll try a simple circuit from Iannini's More electronic circuits for the evil genius. Maybe after working with the tracking device in that book, a VHF (112MHz) with dual 555's for a pulse, I'll figure out how wildlife tracking works. Sensitive receiver and special tuning?

Are you trying to locate a rocket that drifts and lands far from the launch site or are you trying to remotely activate the parachute just before touchdown so you don't have to worry about it drifting far from the launch site?

ZipZapOuch said:

Are you trying to locate a rocket that drifts and lands far from the launch site or are you trying to remotely activate the parachute just before touchdown so you don't have to worry about it drifting far from the launch site?

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That's a good idea. Can there are sophisticated timing circuits for that purpose, delaying parachute deployment.

I'm actually wanting to find my rockets with the classic VHF tracking device.

I want to share an update. I've been reading the article about a radio direction finder. Seems like it will solve my problems. I really was missing a lot of information to base good questions upon.

preWarp said:

That's a good idea. Can there are sophisticated timing circuits for that purpose, delaying parachute deployment.

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If the rocket will turn nose down after the engine cuts off, a simple tilt switch could be used, that closes once the rocket is inverted. Use a fairly long debounce so it has to be closed the majority of the time to be certain it's orientation and not vibration, then a delay timer started by that if needed.

A more sophisticated system could use a barometric pressure sensor and trigger once it's back below a preset altitude.


If you are interested in building RF circuits - why not concentrate on building a good, sensitive receiver that can pick up a legal ready-made transmitter or beacon module?
A sensitive, selective receiver needs more work than a transmitter!

rjenkinsgb said:

If you are interested in building RF circuits - why not concentrate on building a good, sensitive receiver that can pick up a legal ready-made transmitter or beacon module?
A sensitive, selective receiver needs more work than a transmitter!

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Yes I feel like I need to be considering the receiver and consider directional radio finding. I really had a idea that wasn't considerate of other more important factors.

On the rocket idea...all kinds of cool things that can be done. I am reminded of pyrotechnics. Also addressable triggering could be a thing in the modern situation. Just a hunch. But you could trigger other motors. Then there is the very real topic of remote control motion control. Would love to try those things one day.

When I designed tracking for Black Brandt rockets, the Rx used a quad helix antenna and the Tx used an uncoiled dipole that spun out at high spin rate. It would turn point down after apogee due the fins but lose signal every rotation at low altitude 100 mi away on VHF.

I also reviewed polar bear tracking telemetry where chopper pilots would track their migration before and after hibernation with resonant loop antenna using the peak signal for long range and then rotate to nulls for near field for more accuracy.

Archery tracking was also done with HF when arrows missed the target at long range which also used a resonant loop.

My Doppler tracking used OCXO's and a PLL to scale as a subcarrier pilot tone. The ovens were once rather large. Although smaller now, but not practical for scale model rockets. Converting the ground station OCXO to a sawtooth and sampling with the Rx clock ZCD signal, the range could be measured by counting the Doppler difference sawtooths. Azimuth tracking I did with dual Rx antenna and a time interval counter for phase changes. That was all done at the Churchill rocket range in the 70's.

NASA was also launching at one time there and next day we discovered the Nike booster with the familiar O ring burnout.

Just been working on laying out a PCB based on a design for a Voltage Controlled Sine Wave Oscillator. The schematic is from Texas Instruments Application Report SNOA353B. This document has several examples designs using QUAD FET op amps. I am studying this circuit and have plans to manufacture the PCB to gain skills needed to understand the QUAD FETs used in PA8W Doppler Directional Radio Finder I was referred to by rjenkinsgb, earlier in this thread.