Increasing range of 433mHz RF modules- with amplifier? - Page 1
Forum section: electronics / rf-microwave

author: TheD312
author_rank: Contributor
timestamp: September 12, 2018, 03:09:55 pm
content: Hi there,i have just a little quetion regarding 433mHz modules, like the TX118SA Transmitter and RX480 Receiver.Those bloody devices have a range of n more than a good 100 meters.I wonder if the range of these things could be increased with a simple RF amplifier like this one:https://de.aliexpress.com/item/DC-5-7-2-v-1-2A-433-mhz-5-watt-RF-Power-Verst-rker-50/32922667449.html?spm=a2g0x.search0104.3.70.623b10b8bmbV7L&ws_ab_test=searchweb0_0%2Csearchweb201602_4_10320_5016820_10065_10068_10843_10547_5016720_10059_10548_10696_100031_10319_10084_10083_10103_451_452_10618_10304_10307_10820_10821_10302_5016620_5016920%2Csearchweb201603_45%2CppcSwitch_4&algo_expid=99c83c47-5081-4472-a0d3-e290a39b5383-11&algo_pvid=99c83c47-5081-4472-a0d3-e290a39b5383&priceBeautifyAB=0If it would be than how much? I gues 5w of output power should do a good 3km whaI know these amplifiers are banned or require a HAM license in some countries but i was just wondering while i fixed my garage door remote...

author: HB9EVI
author_rank: Frequent Contributor
timestamp: September 12, 2018, 04:04:33 pm
content: If you know, that amps are not allowed, why do you ask then.The laws in Germany about that issue is clear; SDR -> SHORT RANGE devices have their allowed output as well as specified duty cycles.Additionally your imaginations are too simple. Just increasing the TX power doesn't help to reach a certain range; it matters from antennas and their properties, topology of the landscape and other issues.I clearly tell you to forget about using illegal amps for short range devices - on all bands. Just hooking up an amp to a transmitter without knowing what you actually put on air is highly unresponsible, since those amps come all without any harmonic suppression; so next to your wanted signal, you emit plenty of unwanted harmonics, which can interfere with sensitive radio signals like police, SAR - and about that the regulation authorities don't know any fun!

author: mrf184
author_rank: Contributor
timestamp: September 12, 2018, 04:39:33 pm
content: The RQA0009 can put out about 5W at 6V, and the RQA0009TXDQS datasheet includes a reference design for 465MHz which also works at 433MHz.For higher power I'd look at mrf184 and mrfe6s9125n. Both are about <$5.

author: TheD312
author_rank: Contributor
timestamp: September 12, 2018, 05:10:17 pm
content: Thanks. But i wasn´t looking for RF transistors, i just wanted to know if the range could be increased.Is there actually any way to increase the range of a garage door remote? Because 30 meters sucks...

author: mrf184
author_rank: Contributor
timestamp: September 12, 2018, 06:23:47 pm
content: if you have line of sight or near line of sight and a high transmit site then 1W at low UHF will get you a few km. Height above ground is very important because of the fresnel zone. If both transmitter and receiver are just 1m above ground level, expect no more than 1km unless you have perfect line of sight. If in a city, and there are buildings in the way, with transmitter and receiver at ground level, from my tests you need 10W to get about 1km with a very narrowband signal (100hz), and to get any data across (10kHz or more) the same 10W will get you past no more than a few apartment blocks. This is all assuming antennas are outdoors. Indoors the windows will attenuate your signal at least 10dB, so you need 10 times the power to get the same range.To answer your question 1W will likely get you range that is just past one or two buildings in the way, depending on geometry.

author: ThomasDK
author_rank: Regular Contributor
timestamp: September 12, 2018, 07:04:59 pm
content: A good reciever antenna would be the first thing to try.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: September 12, 2018, 09:16:26 pm
content: As well as a good receive antenna I would suggest a high quality receiver. The ones supplied aren't very selective and pick up lots of noise.I got over 1km with a handheld transceiver used as a receiver.An index page to my other UHF module experimentshttp://home.alphalink.com.au/~parkerp/projects/projuhf.htm

author: Lord of nothing
author_rank: Super Contributor
timestamp: September 14, 2018, 02:53:39 pm
content: It depends how does the Building is build with.A Carboard House who is used in the US is less dence then a European Home with Metal Coated Window and Styrofoam outside.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 14, 2018, 03:26:54 pm
content: You can get 100mW 868MHz moduleshttps://uk.farnell.com/rf-solutions/zulu2-m868-so/radio-modem-module-868mhz-115kbps/dp/2759270?krypto=puVm1LFFlHVVXDE20Q8VU%2BUf0EU9G2o7boj5ufeeELjOiKtqCMH378lKayDu5STWiY%2BtDWed8fSYdOlsLuSMD7LNLTo%2FwHJmEDuLglBynF4%3D&ddkey=https%3Aen-GB%2FElement14_United_Kingdom%2Fsearch

author: Lord of nothing
author_rank: Super Contributor
timestamp: September 14, 2018, 03:59:58 pm
content: or get a CB Radio with Sound Modem you can transmit with 12W Peak.

author: tkamiya
author_rank: Super Contributor
timestamp: October 02, 2018, 12:30:46 am
content: You are looking at an amplifier without any filtering. I wouldn't be surprised it has harmonics near and far well into GHz range. If you should cause interference to other services, you are looking at heavy fine and possibly some jail sentence. I wouldn't do it. In US, ham radio license will allow us to use it - and that much is correct. But that also assumes we know enough not to pollute, and in case it does, we are fully liable.

author: Chris Wilson
author_rank: Super Contributor
timestamp: October 03, 2018, 12:08:01 pm
content: A Yagi RX antenna is pretty small at that frequency, so if you can put up with directional receive capability one would considerably increase the reception range. Likewise a TX Yagi with similar provisos. An amp will of course increase the range of the transmitting device but at those frequencies they are not very forgiving and will need a filter on the output to kill unwanted frequencies. I'd try a decent RX antenna firstYou could also make a simple none directional J pole RX or TX antenna for next to nothing.

author: tautech
author_rank: Super Contributor
timestamp: October 08, 2018, 12:15:34 am
content: Quote from: Chris Wilson on October 03, 2018, 12:08:01 pmThat's exactly what I did here:https://www.eevblog.com/forum/rf-microwave/antenna-project-log/If you need more range mostly you don't need raw grunt to get it.