receiver module , antenna help .

[max_imum2000]

i recently bought a small reciver module from china, datasheet is here

https://www.electro-tech-online.com/custompdfs/2010/01/RM4SH.pdf

the remote distance is very short, its supposed to be a 3000m range remote from the same manufacture.

i tried to attach a piece of wire to the module , and it stopped working completely , no receiving of any signal ?!!

why i dont know ?

any ideas

thanks

 

[Sceadwian]

It's supposed to have a 23cm wire attached to it's output, where are you attaching the wire to?

 

[max_imum2000]

there are a pin market ANT and beside it another pin GND for ground
so i attach the wire to the ANT pin

 

[Sceadwian]

Right, it shoudl be 23 centimeters long and straight up from the ground plane of the board.

 

[max_imum2000]

actually its a 433mhz module to its supposed to be 17cm
but what do u mean stright up from the ground plane ?
ANT and GND pins are not the same and not connected

and why it stop working if i attach any wire to the ANT pin alone

thanks for your help

 

[Sceadwian]

Do you have the datasheet for the full module? The one you posted doesn't even show which line the antenna is.

 

[MikeMl]

Do you have the datasheet for the full module? The one you posted doesn't even show which line the antenna is.

I'm guessing it is one of the two big holes down at the end of the PCB opposite the header. The CHINGLISH on the data sheet calls it "RECEIVING INSTRUCTION"

 

[max_imum2000]

i never tried to connect it to this pin "receiving instruction" i will try and let u know
this module is 4 channel module, when i press a button , it momentary switch one of the corresponding outputs high
this pin is high whenever i press any button.
no data sheet for this module as many Chinese products.

the ANT pin which i think is antenna , is connected to IC 3310A pin thought a resistor

i can take photos if that will help

thanks all

 

[max_imum2000]

here it is. the pin is at the top left corner

 

[MikeMl]

I see ANT at the top right as the photo is posted?

 

[max_imum2000]

sorry my mistake thats it, when i connect any wire to this pin
the module just stop working at all
any idea ?

 

[MikeMl]

sorry my mistake thats it, when i connect any wire to this pin
the module just stop working at all
any idea ?

Where is the transmitter when you connect the RX antenna?

It is possible that you have a strong interfering signal in the vicinity. With the antenna connected, the interference might be blocking the receiver. With no antenna connected, the nearby transmitter can overwhelm the interference.

 

[JimB]

It is possible that you have a strong interfering signal in the vicinity. With the antenna connected, the interference might be blocking the receiver. With no antenna connected, the nearby transmitter can overwhelm the interference.

I was thinking exactly the same.

JimB

 

[max_imum2000]

i dont think there is any interference ,
however i took the circuit and placed in completely different room, with nothing close to it
exactly the same behavior
the strange thing is that when i put the remote very close , the circuit stop working as well !!

thanks guys for all your help

 

[MikeMl]

...
the strange thing is that when i put the remote very close , the circuit stop working as well !!

RF overload! Put the antenna on, and then have someone walk away with the transmitter while you watch the receiver decode the signal. I'll bet that at some greater distance, it will start to work...

 

[max_imum2000]

MIKE , you gut it.
i think its RF overload,
once i walked away from the receiver it started to work and the antenna was installed.

however now the behavior is strange, when i walk really away it wont work
the remote is 1Watt power to it should work from a good distance.

could that be related to RF overload ?
how can i control this

thanks a lot

 

[audioguru]

RF overload is controlled by tuning the wanted signal at the input ahead of the RF amplifier. Cheap circuits amplify anything and exerything (and therefore are overloaded) before the tuned circuit.
Good circuits have a wide useable range of input level. Cheap circuits are overloaded.

Is your cheap circuit designed and made in China? Too bad.

 

[max_imum2000]

you are correct that its a cheap circuit , couldnt find anything else
but everything is made in china these days, they are not to blame

 

[Sceadwian]

Nope, yours for buying a cheap RF module =\
You get what you pay for in the end.

Do you have any concrete range requirements you're shooting for? You could use your module as is for basic testing at the ranges it's happy with, but you need to buy a better module

 

[max_imum2000]

anyone here can direct me where to buy a good 5V receiver module ?