Filter for PMR446? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: January 03, 2017, 09:51:00 pm
content: HiI will install an Antenna for PMR446 Reception. I could not find any Filter to get the noise out who are there.Does anyone know someone who have every made one or any company who sold some?Thanks

author: TheDane
author_rank: Regular Contributor
timestamp: January 04, 2017, 11:59:35 am
content: If there is traffic already on the frequency, and it's not a harmonic distortion - no filter will be able to remove the 'noise' on your link.If it is harmonic interference, try installing a common 70cm ham Rx(Tx) filter, the frequencies are quite close together and should work beautifully - you can build one easily, or buy it from a local ham shop.You can also use a 70cm ham band antenna, they might be cheaper tooGoogling "70cm ham antenna filter store" gives quite a few results

author: Lord of nothing
author_rank: Super Contributor
timestamp: January 04, 2017, 03:50:58 pm
content: Quoteamateurband is on 430 - 440 and pmr446 runs on 446mhz. the 6mhz could be to far from the band.Quotethere isnt anythink like this.QuoteI have nothing to build anything.Quoteor an Commercial for example: Antenna Base Repeater Motorola UHF 450-470mhzThe major think is a filter who help me getting the best result.

author: TheDane
author_rank: Regular Contributor
timestamp: January 05, 2017, 09:37:32 pm
content: According to wikipediahttps://en.wikipedia.org/wiki/PMR446the maximum radiated energy (ERP) is commonly limited to 500mW in most countries.An antenna tuned to the 70cm band won't drop off like a vertical cliff, but will also be quite useable at frequencies close to its center freq.- you will most likely see a miniscule increased SWR at worst -https://en.wikipedia.org/wiki/Standing_wave_ratio- but depending on your cabling and antenna mount position, the last two factors often plays the better of getting good antenna Rx/Tx signals.HF frequencies often utilize a single antenna and frequencies spanning multiple megahertz - and if the power is high, an antenna tuner to ensure the transmitter is not blown up by the returning power (SWR). A high SWR ratio won't usually effect Rx operation, besides making the receiver a little more deaf due to the destructive effect of the received/reflected wave/energy ratio between antenna 'output' impedance and the radios input impedance.Antenna filters can often be made by self wound inductors (wire) and salvaged capacitors from old/broken electronics.Ebay is also a good place to get stuff:http://www.ebay.co.uk/bhp/pmr-antenna(Notice these are also sold as 70cm antennas)

author: Spuddevans
author_rank: Unknown
timestamp: January 05, 2017, 10:47:11 pm
content: Quote from: Lord of nothing on January 04, 2017, 03:50:58 pmI can assure that a 70cm antenna will work almost perfectly for PMR446, most antenna's have some adjustment facility to tune them, and usually they can easily tune to a slightly higher frequency.Added to that it seems that you want this purely for reception? In that case the very minor difference would make absolutely no difference. The major need for tuning is for transmission. My 2m/70cm antenna picks up pmr446 perfectly, and also receives well above 500mhz with no discernible signal drop-off. (it also receives Airplane traffic great, 119-130mhz)Tim

author: Lord of nothing
author_rank: Super Contributor
timestamp: January 06, 2017, 02:11:42 pm
content: QuoteI will search on ebay.Quotethe most people use baofeng and other radio who have an huge output power.