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What is the power rating?
some modules need high current.
Some modules require a regulated 5VDC supply. Switching supplies may be used though special care must be taken to ensure optimum performance as noise on the power supply can affect the operation of the radio.
Most step-up and step-down switching supplies and even some RS232 level converters can introduce ripple into the power supply. The magnitude of this ripple must fall within the radio modem specification of +/-0.25V as per the manual.
Care must be taken to ensure that the frequency components of the ripple do not affect the radio performance. Frequency components between 20kHz and 100KHz are particularly harmful to the performance of the radio. A simple L-C lowpass filter should be used to block the switching noise that otherwise may reduce the performance of the radio module.
If you intend to build a 9V PS, I'd suggest Transformer + Rectifier + Smoothing + 9V Regulator, see: Power Supplies
Otherwise get an off-the-shelf $10 switchng 9V/500mA PS ..
Hello All
For what frequency ? the power supplies , for RF systems , should have some important characteristics . so it depends on the frequency of module , and the maximum power , and the area of operation ( for example is that circuit in factory ? or ....)
my mean is the noise of area . and some other things.
Best Wishes
Goldsmith
IanP is right. A good linear regulator will do the job assuming cw low power operation. If the PA stage of the transmitter is likely to transmit high power (and possibly saturated) spikes, the capacitor requirement at the output of the linear regulator may require extra attention. In this case some other solutions like efficient pulsed regulators may be required.
Dear keith
Hi
I told at post #5 . some of reasons .
Consider , about , the high frequency , current ! it can destroy , the behavior of feed back loop . because the frequency of ripples will be high , and feed back network and the op amp that used at this loop can't sense these effects .
According to the frequency of operation and some of things that i told at top , we can design best supply for that . so for example give me a frequency , i'll design best supply for it , and will put it here .
Regards
Goldsmith
Your post doesn't explain your statement "a simple linear regulator for RF systems isn't good". Linear regulators are very common on RF systems and work well. I have used them a lot for transmitters and receivers up to 1GHz. You just need to make sure you decouple them correctly for RF frequencies.
Switching regulators can be more tricky to get right because switching noise on the regulated supply lines can interfere with transmitters and receivers causing phase noise and additional mixer products.
Ho much was your power ? when i designed a simple MW , transmitter with 1.6MHZ at the power up to 600w , it's performance was not as i thought at theory ! ( i'm talking about 4 years ago .) and when i added some EMI filters at the path of it's supply , ( it supplied with a linear regulator ) it's behavior went to the better situation . but not good . and i added some fast feed back loop and some filters to it , it worked , with high quality ! i read many books about power supplies for RF systems and audio systems .
the supply of them ( audio and RF are completely different together . ) and the power supply is the important piece of each transmitter i had problem with improper supplies , with the frequencies , up to 35MHZ . but when i designed my first 100MHZ transmitter (15W) it had no problem with supply . and i know that what was the reason . the reason was , that at this frequencies the wires are alike with EMI filters . so at frequencies above 50MHZ , there is not any special problem .
because of this , i asked , that what is his frequency .
Regards
Goldsmith
My power transmitters have been around 60W in the 30MHz to 200MHz range. No problems with linear power supplies. I agree they are important but I don't see anything inherently wrong with a linear supply with RF systems, either transmitter or receiver.
My power transmitters have been around 60W in the 30MHz to 200MHz range. No problems with linear power supplies. I agree they are important but I don't see anything inherently wrong with a linear supply with RF systems, either transmitter or receiver.
I just want a power supply schematic for normal home indoor or outdoor environment. The transmitter is 27 MHZ, I’m using 9 v DC battery, I don’t know the power of the transmitter, but the vrms at the antenna reads around 3 volts rms. Will the 9 dc do in these environments? The transmitter works fine so far.
Dear zeller
Again Hi
If the impedance of your antenna is about 50 ohms , thus the maximum power across it will be about 180mw .
so do you want to supply it from main power line ? if yes , i'll send you a good and simple circuit.
Good luck
Goldsmith
Dear zeller
Again Hi
If the impedance of your antenna is about 50 ohms , thus the maximum power across it will be about 180mw .
so do you want to supply it from main power line ? if yes , i'll send you a good and simple circuit.
Good luck
Goldsmith
Thanks for your help.Maybe I may have created some confusion. Basically I designed a 27 mhz AM modulation transmitter which I intend to use for remote control purposes together with decoder/ encoder HT12E/D.The transmitter works fine so far with vrms of 3v read from an oscilloscope.But i read somewhere that to get a better output (with less noise) a separate power supply is used i.e that i need to attach more components i.e capacitors etc along my 9v normal dc battery I'm currently using to power my transmitter - for smoothing out?. I don't intend for now to increase the output power although in the future I would like to know how my VRMS can be increased.
The power supply im using now may probably be appropriate for remote control purposes for this project but I thought a more sophisticated power supply may help. I am not an expert electrical engineer.
Thanks.
---------- Post added at 23:56 ---------- Previous post was at 23:55 ----------
Dear zeller
Again Hi
If the impedance of your antenna is about 50 ohms , thus the maximum power across it will be about 180mw .
so do you want to supply it from main power line ? if yes , i'll send you a good and simple circuit.
Good luck
Goldsmith
Thanks for your help.Maybe I may have created some confusion. Basically I designed a 27 mhz AM modulation transmitter which I intend to use for remote control purposes together with decoder/ encoder HT12E/D.The transmitter works fine so far with vrms of 3v read from an oscilloscope.But i read somewhere that to get a better output (with less noise) a separate power supply is used i.e that i need to attach more components i.e capacitors etc along my 9v normal dc battery I'm currently using to power my transmitter - for smoothing out?. I don't intend for now to increase the output power although in the future I would like to know how my VRMS can be increased.
The power supply im using now may probably be appropriate for remote control purposes for this project but I thought a more sophisticated power supply may help. I am not an expert electrical engineer.
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