rf power amplifier does not strengthen my sdr!!! - Page 1
Forum section: electronics / rf-microwave

author: stw
author_rank: Newbie
timestamp: November 08, 2022, 05:18:14 pm
content: I have a 1 watt PA and bladerf.My PA input power +10dbm.but my amplifier is not boosting my sdr.The amplifier is solid, why is it not boosting? It goes from -60 dbm to -54 dbm in the spectrum, but this is not the result I expected.

author: TheMG
author_rank: Frequent Contributor
timestamp: November 08, 2022, 11:53:43 pm
content: Need more details. What is the model of the amplifier? What are its specs? Particularly gain specs.To go from 10dBm to 30dBm (1 watt) requires an amplifier with 20dB gain. Does the amplifier have 20dB gain?

author: geggi1
author_rank: Frequent Contributor
timestamp: November 09, 2022, 07:27:16 pm
content: First of all.What is the TX output on your BladeRF? you will need 0dBm to drive the amplifier fully to 1W. if there are any ajustment in the software check your settings.Does the powersupply supply the required current and a stabile voltage?Is the amplifier hooked up correctly.? Blade RF output to amplifier input?

author: radiolistener
author_rank: Super Contributor
timestamp: November 09, 2022, 11:52:57 pm
content: probably your bladerf output has not enough signal level in order to drive the amplifier up to 1 WattWhat is bladerf output power level?What is amplifier gain?

author: TheMG
author_rank: Frequent Contributor
timestamp: November 13, 2022, 01:30:34 am
content: What frequency are you using it at?

author: rfclown
author_rank: Frequent Contributor
timestamp: November 19, 2022, 01:55:25 am
content: Quote from: stw on November 11, 2022, 04:57:15 pmFrom datasheet:Amplifier Power-up Precautions9.) Confirm the input power level at the input port of the amplifier does not exceed the maximum rated limit for input power (as stated in the Amplifier datasheet).Pin for Small Signal Gain = P1dB-SSG-10 dBPin for P1dB = P1dB-SSG+1 dBThis is usually stated much more clearly in a section called "Absolute Maximum Ratings", but I didn't see that in the datasheet.P1dB and SSG are 30, so max input would be +1 dBm. Hope you haven't blown your amp.Verify DC voltage at amp power supply pins. Monitor current to see that it matches datasheet. Make sure frequency is 0.5-4.0 GHz. You say PA input is 10 dBm, but then later say blade output is +6. Did you measure this with a spectrum analyzer? How did you measure the output with the amp? I hope you used an attenutator, because a watt can blow the input of a spectrum analyzer.

author: radiogeek381
author_rank: Regular Contributor
timestamp: December 18, 2022, 04:05:38 pm
content: QuoteHmmm... I'll put this as gently and supportively as I can. Please take it as friendly advice.I think you have taken on a project that is beyond your current knowledge and abilities. Your last note was the final hint.1. RF power is usually measured with an RF power meter. (For those who suggest a spectrum analyzer, that's fine, but isn't my first choice when dealing with amplifiers.)2. You haven't mentioned which frequency you intend to use. This is important, because there are spectrum allocation rules and rules about power and emissions and time and all kinds of other things that you may not have researched. And the rules are important.3. If you "don't have an attenuator at hand" and you connected the amplifier output to your spectrum analyzer, any reasonable output from the amplifier will have blown the front end of the spectrum analyzer. It is no longer useful for power measurement.--------I would suggest that you find someone who has some experience to sit with you (online help from forums doesn't count) and can talk to you about what you *need* to do, rather than how you want to do it.That's a $4K power amplifier. I'm getting the impression that you are doing this as part of a research project or because you got assigned a task at work. If you are doing this as a commercial venture then you really need to engage someone who has some experience in this area. If this is a personal research project, I admire your ambition. And if it is graduate student research, there ought to be someone at your institution who could help.Fortunately lack of knowledge is not incurable. With time you may acquire the background to get through this on your own. But that takes time and help. Focused help, not help in bits and pieces of forum posts no matter how competent the posters are.Respectfully (I've been there)