(Part 4) How to Design, Build, and Test an RF Linear Amplifier (Input Board Con't)

This multi part video focuses on the critical design aspects of an RF Push-Pull amplifier. The example shown uses an IRF510 MOSFET transistor to explain impedance matching, biasing, amplifier classification, circuit stability, feedback, tuning, power output, harmonic distortion, and other important design characteristics. It also introduces LTSpice as a simulation tool. From this video, the viewer will gain an in-depth understanding of how to design, build, and test an RF power amplifier. Please visit my web site for the RF amplifiers and other products I offer. rflinear-amplifiers.com

[@deuce-way1440]

NICE! You taught me a few new things about lt spice

[@camodudeA51]

Thank you RF Man for such a great series of learning, we've learned so much in such a short time...can't get enough so hope to see more content like yours.😊

[@emailuser3869]

Amen!

[@rfmanchannel6915]

Thanks for you feedback!!

[@minazulkhan8287]

Great video.

[@AllElectronicsChannel]

Thank you for the video, my friend!

[@rfmanchannel6915]

Thanks Gregory! I watch your channel all the time! The content is great! Thanks for all you do! Rob

[@bob_mosavo]

Thanks 🤩

[@nickk48]

Good presentation, but note that you can't calculate SWR as the ratio of the magnitude of the load impedance to 50 ohms, if the impedance is complex.

[@Eletronicafg]

I noted that too, otherwise a purely reactive 50 ohms impedance would result in a perfect 1:1 SWR instead of infinite SWR!

[@ildabrando]

FANTASTIC serie! Can You tell us how did you choose the value of the R (60 Ohm) in parallel with the secondary of the transformer?

[@bigal159]

Really enjoying this series, big thanks! Would you mind providing a link to the IRF510 ltspice model you are using. There seem to be many different ones available.

[@rfmanchannel6915]

Please send me an email and I will send it to you. Regards

[@cristianstoica4544]

Thanks for the series! On practical terms, I assume you already have a good idea of how much inductance you get from your cores. How do you confirm that? What do you use for measuring? I'm asking for LC meter recommendations for beginners if you can give one.

[@rfmanchannel6915]

This is a good LC meter to start with. It can measure down to the NH range with good accuracy. www.amazon.com/Goupchn-Inductance-Capacitance-Measuring-Instrument/dp/B08PDZV6R7/ref=sr_1_7?crid=1S6PO1NEWI20O&keywords=LC+Meters&qid=1682432484&sprefix=lc+meters%2Caps%2C290&sr=8-7

[@yassinabdullah5209]

Thank you RF man, it is an amazing series of videos about building amplifiers. i was searching for this information for a long time.
I am a Ph.D. student, and I would like to do my research on CMOS power amplifiers and low-noise amplifiers, I hope I can find an easy way to contact you and benefit from you.
pleas provide me any contact that I can reach you.
Best Regards

[@nickk48]

Note that in LTSpice, you can't used MHz for megahertz. You must use MEG or else E6.

[@user21XXL]

Hi, thanks for sharing. I would like to ask about time parameters of IRF510 - since its operating in AB class does it mean that turn on and turn off delay parameters are not important - can the AB class operate faster?

[@minazulkhan8287]

Hi , i owe a nano vna and i m new to rf. Can u show schematic how u have connected it. I do not want to destroy my nano vns. Have u used attenuators ?

[@johnward7619]

Great material, 73 de ZS1EQ

[@rfmanchannel6915]

Thanks for your feedback!

[@Davidsmith218]

Could this work with a irfp260n for a higher power output

[@rfmanchannel6915]

Yes, the input impedance may not be the same so the turns ration on the input transformer may need to be modified. Also the size of the RF Chokes and output transformer may need to be larger. The current deign can safety handle 100 watts. 73

[@Davidsmith218]

@@rfmanchannel6915 with the irfp260n it could be possible to get as high as 800w+ say with 4 in parallel

[@macgman2000]

I must have missed it. On the transformer inductance. How did you arrive at 11.2uH? Seems to just appear without a calculation.

[@fredfred-im9px]

Are you using the IRF510 from LT spice data base. I have copied your circuit and ran it on the LT spice. It gives totally different result. It appears that you are using some other IRF510 data parameters. I can see .include irf510.txt statement on your circuit diagram. If so where did you download the parameters from. Thanks

[@rfmanchannel6915]

No, I found another model on IR's web site. If you email me, I can send it to you. [e-mail]

[@ETHIOMUSIC-ls5zu]

sir how 60/50 hz frequency changed to Ghz how cicuit change it

[@cbnation1]

If you need a 1:1 ratio, how do you choose the number of turns? 1 on both sides? 2 on both sides? That was not clear to me.

[@rfmanchannel6915]

It no that critical 2 or 3 turns is fine. Regards

[@shehabeldinahmed1156]

where are the mosfets on the real board i can’t find it

[@ltlt6117]

Hi i made a common emmiter amplifier for 200mhz signal with 2× gain
I can amplify a 50 mv p-p to 100mv p-p but I can't do it for 2v to 4v p-p
Why what values should be change???

[@rfmanchannel6915]

Please email me the schematic and I will take a look. [e-mail]

[@Davidsmith218]

Please help irfp260n

[@rfmanchannel6915]

Hello David, I just viewed your video and have some suggestions. I would recommend that you increase your bias voltage to bias the amp in Class AB. You will need to measure the drain current while adjusting the bias voltage level. The idle current for 4 devices should be 500mA or so with no input signal. Also, I would add 2 RF chokes (30uH) to better filter your 50 volts. If you are looking for more power output, your output transformer will need to be larger (2 ferities stacked). I hope this helps. RF Man

[@Davidsmith218]

@@rfmanchannel6915 I'll try the chokes