[Moved]: Will this 433mhz antenna amplifier work?

Hello,

I found very cheap 433MHz transmitter/receiver kits on ebay (see image attached). They have poor range. I am wandering if one-transistor amplifier attached before transmitter antenna will extend the range.

I have designed one transistor amplifier myself (see image attached) and doubt it will work properly. In theory (according LTSPICE simulations) it should extend range six-fold.

Since I have never dealt with such devices before I need your advice.

Thank you in advance

Most likely you already realize it's important how you orient the antenna (both transmitting and receiving).

Do you have an rf detector for 433MHz? A meter with a scale reading showing intensity of reception?

Not quite the answer to your question, but what kind of range did you get and are looking for?

I experimented briefly with exactly the same pair of modules last month and got usable reception at 120m in clear LoS. The farther I moved them apart, the more important antenna orientation became. I used a few inches of enamelled copper wire for the antennas.

Last week, I modified a pair for a friend who needed linear modulation instead of OOK which these simple modules are intended for.

Pjdd said:

Not quite the answer to your question, but what kind of range did you get and are looking for?

Click to expand...

Thank Pjdd,

I do not have the modules yet (also i do not have VHF/UHF detectors etc), that is why I am thinking should I order them or not. I would like to extend range up to 1-2 km with help of antenna amplifier. There are 2km range modules on ebay too, but they are about 20 times more expensive.

truffaldino said:

Thank Pjdd,

I do not have the modules yet (also i do not have VHF/UHF detectors etc), that is why I am thinking should I order them or not. I would like to extend range up to 1-2 km with help of antenna amplifier. There are 2km range modules on ebay too, but they are about 20 times more expensive.

Click to expand...

these things were only designed for the short range low power ISM band, garage door openers etc etc

taking them higher than this in power level negates their non-licence standard and they will then easily interfere with other licenced users of the band
If you did this near my home you would need to expect visits from the authorities


Dave

why do people keep posting these horrible ideas. NOBODY uses discrete transistors anymore for amps. Go to mini circuits, pick out an amplifier integrated circuit, and use THAT instead. I mean this is not 1990

davenn said:

If you did this near my home you would need to expect visits from the authorities


Dave

Click to expand...

There will not be problems with authorities: I will use it in the field: Just want to nstall it on my RC glider to get info about altitude and similar stuff.

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biff44 said:

why do people keep posting these horrible ideas. NOBODY uses discrete transistors anymore for amps. Go to mini circuits, pick out an amplifier integrated circuit, and use THAT instead. I mean this is not 1990

Click to expand...

I am posting that because I have no idea about such circuits. If you had useful info, please share it with me. Besides this discrete amplifier could be much more cheaper solution.

ah. so here is what you want to do. Pick a RF IC that is easy to use. That would mean one with high gain and high output power, but not too high of a frequency response. In other words, do not pick an 8 GHz amplifier chip if you only want it to run at .43 Ghz! You will just have trouble making it work as a stable amplifier.

Here is a good starting point: RFMD's SXB-2089Z

**broken link removed**

it is easy to "breadboard" into a circuit, since there are two nice ground leads on the package (the middle small lead, AND the big heat sink lead, are both connected to ground).

It will put ou5 qn hon3w5 00 milliq55w q5 433 MHz. The data sheet shows a typical schematic on how to use it. just make sure you have a ground plane on one side of the board, and use at least TWO via holes to ground for the device.

You can find similar types of ICs on Ebay (older style) that work fine. I usually have a few envelopes of 20 each of a few different types of these amplifiers for quick breadboarding.

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"it will put out an honest 200 milliwatts at 433 MHz"

truffaldino said:

There will not be problems with authorities: I will use it in the field: Just want to nstall it on my RC glider to get info about altitude and similar stuff.

Click to expand...

Sorry to go on about this aspect of the responses but this is EXACTLY why there are power and hence range limitations on the use of this band.
When you put an transmitter up in the air, then you can draw a 2km circle around that to include all of the locations where your signal can be picked up. That equates to a 2km radius of interference!
For the sake of others, please do not do this.
Susan

truffaldino said:

There will not be problems with authorities: I will use it in the field: Just want to nstall it on my RC glider to get info about altitude and similar stuff.

Click to expand...

OK so use the band(s) allocated for RC work, specifically the 2.4 GHz band.... there dozens of transmitter and receiver modules available from your local and not so local hobby shop
specifically for this purpose .... do it the correct way :smile:


Dave