RSW 434

[butchH]

looking for a schematic of the rsw434
problem:
When the transmitter is to close (<10 feet) the RSW434 only receives for a short time.
The op amp on board has a good small signal at the + input but the - input rises to a point that the output stops. Is this suppose to be some type of AGC?

 

[rumpfy]

I tried to help by looking up rsw434 but got rws 434. data sheet shows the tx and rx to be small modules with no access to on board connections. It is conceivable that the input overloads when the tx is close. The output power of tsw 434 is 16 dBm which is 40 milliwatt.
So, I'm not sure what youve got or whats happening cos yr description doesnt fit the facts I have.
I got a data sheet from wenshing and it refers to AGC but doesnt say the AGC function can be accessed. Not sure about your '+ input' and '- input'.

 

[butchH]

 

[butchH]

The + - pin I am referring to are on the opamp chip. The actual data pin works and then stops, the analog pin fades away over the last few mS. That is why I investigating what is on the PCB. If it is saturating the front end wouldn't it be saturated from the beginning of the transmission?
I started tracing the circuit to figure out why it works this way. But I've been traveling this week so everything is at home while I'm in a hotel. Once I figure out what the circuit is I can either modify the PCB or build it my way.
Already added a squelch circuit to cut down the random noise out of the data pin.
This was to be a quick simple project that is turning into a research project.

 

[butchH]

Well had some time to trace the circuit and found that of the collection of RWS434 boards I have there are at lease 3 different versions. The analog amplifier is AC coupled in all but 2 of them put the cap at the bottom of the negative feed back resistors. One version has the cap in series with the plus input. This version can receive a large signal and not saturate the amp to one rail.
Now the game is to figure how to get a few more of the good version. The adds don't tell you about this and the data sheets only list the absolute minimum.