Відео

Thanks for this great tutorial! 73 de on2mvh

I really appreciate the quality presentations you make here. I have recently retired and have been a ham radio operator for a very long time. I have started watching your videos and studying them carefully. I have a real thirst for the kind of practical knowledge that you’re presenting so professionally. I’m looking forward to starting some home-brew projects. The art of RF impedance matching has always been a bit of a mystery to me even though I have some basic knowledge of it. You have made the subject much clearer and easier to understand. I’m assuming much of this transfers to vacuum tubes as well. I’m hoping to experiment in that area too. I wonder if you have ever done any vacuum tube impedance matching videos. As in matching between different RF amplifier stages. Thank you so much for all your efforts and I look forward to your great content. 73

Dear Sir ! Your videos about RF amplifier are more informative and precious ! ❤❤😊❤❤❤ Please make a video on " How to use the transmission line T1 as a component in the LTSPICE to measure VSWR RATIO of a transmission system?" Thanks a lot Sir ! ❤❤😊❤❤

‏‪0:24‬‏ Thank you, thank you.

Well explained 👌

Great video! How reliable would the 0.1 ohm resistors prove to be in the long run if these dc converters were being used daily? Why does this solution cause the converters to share load more equally? Is it due to the impedance of the converters not matching and having very small impedance? What is the impedance of those boost converters?

Thanks RF Man for your videos! I note that the input and output grounds are not exactly common on these (sz-bt07cccv) boosters. I'm concerned that the Under-Voltage Protection UVP and current sensing is implemented on the ground side of these boost converters. If UVP were to trigger on one of the inverters, that inverter would open its input ground and use the output ground of the other parallel-tied inverters, thereby circumventing the UVP and causing the current sensing and therefor current limiting of that converter to be vastly incorrect. One possible partial solution is set the UVP very low so it never triggers. Did you consider this and did you have any concerns or experience any issues?

What is common poise in ham radio

Is it possible to align a class E amp without having a current probe attached?

Are there UHF signal repeater circuits?

Thank you so much for presenting this in such a clear and practical manner. I watched all 6 with great interest. I'd like to do something similar for 500kHz. I think a core material of 73 or 77 would be optimum. Can I bother you say what ferrite core part numbers or vendor you used for your amp please? Were they Amidon? Thank you!

you made the most clear transition from Sokal's equations to practical implementatiion of a class E amplifier I ever saw... Thank you, and PLS send me your spreadsheet, as I am interested to experiment in the 80...10m amateur bands with low cost / good quality an good performance gear.

Thanks for the excellent series on the IRF510 - Do you perhaps still have a copy of the printed material you used during this series? I'd like to build one of these and toy around with the circuit a little and having it in PDF would be really useful. Thanks!

Now, with an IRF530 that won-t match.

Sure, the NanoVNA takes the impedance measure for you. LTSpice can't replace it.

Mistake on your printed sheet. VSWR of 56/50 is not 1.0:1, it is 1.2:1

Thanks for taking the take to record and edit all the parts of this series of videos. What I miss from your videos is the impedance of the IF510 input. You never mention it. You spend a lot of time explaining the matching impedance process from 50ohm, to 25ohm, but you never said how you got that value. You are assuming each gate of the IRF510 has an impedance of 12.5ohms, as you are using a pair, those inputs are in series, then you came up with 25ohm value. Doing more research I found the Gate of the IRF510 has an stray capacitance. Vishay datasheet says typical value for Ciss is 180pF... at 10Mhz you got Xc=88 ohm. For 30Mhz you got 29Ohm... your impedance network may not work right at lower frequency of 10 Mhz.

Very well explained man. 73s

Hi, I have followed through this class E RF Amplifier design by using the ClassE app by tonnesoftware. Instead of using the L-network provided by the ClassE, I used the PiEL from tonnesoftware as well to design the matching network. The LTSpice simulation showed very promising outcome. However one of my concern is VSWR, how good is the circuit recommended by this software handle VSWR or is there any material to read to study more on VSWR? Thank you in your presentation.

Can't watch; getting motion sick from bouncing camera.

Hi, I'm following your interesting tutorials, and I'm building a board like the one you describe. There's a tool I'd like to have, and it's the 4w amplifier you use with the function generator. Is it possible for you to upload the schematic of that amp? Thanks for your reply and your professionalism in teaching, best regards.

Hello! How interesting it all is! You explain very clearly. Thank you very much for your work! Very, very useful video! Please make such videos as many as possible and in more detail. This will be your legacy and will be useful to many radio amateurs. Thank you!

P : 60V X 30A = 1800W, RF power : 1250W, so it was 1250/1800 = 69% efficiency? Is it correct? And so about 550W is dissipated as heat? So will need large heatsink and fan

Muy bien explicado

Ahora comprendí para que es la resistencia en paralelo en el secundario del trafo de entrada a la placa, excelente

Don't believe what this guy is telling you folks. An amplifier ONLY amplifies the signal going into it. Nothing more and nothing less. The RF Man guy likes to call the FCC on his competition as well. Your amplifier is only going to be as dirty as the radio or input signal going into it. You want to be LOUD over the air? I've got news for you, clean isn't mean. You want BIG LOUD AUDIO!

Extremadamente útiles tus clases de RF, agradecido por ello. Un saludo, EA7KNH

Muy buen trabajo, gracias por compartir, EA7KNH

When testing the splitter at the end of the video, shouldn't the other port be terminated into 50 ohms?

The question is related to the RF push-pull amplifier. What will be the result, if we assembled a push-pull RF amplifier circuit of 7 RF same transistors like 2N3866 ? Consider there are 7 RF transistors 2N3866 as A, B,C,D,E,F,G. Transistor A is a driver transistor of output transistors B and C, whose conduction angle is 180 degree. Transistor B is a driver transistor of D and E, as well as transistor C is a driver transistor of the transistors F and G. And the each output transistors D,E,F,G are conducted at an angle of 90 degree , ok ? Can this configuration of 7 RF transistors works well ? And the efficiency of this amplifier will increase well ? Because each output transistors has conduction angle of 90 degree. Please explain with great affection and lovely approach.

Bit too shaky for me

What material for VHF 2 meter frequencies?

At the end of the movie, you did not explain where the additional 25ohm pure resistance came from. Did you endure reactance and pure resistance was connected ???

Is there somewhere I can find a gerber file library? These boards would only cost a few dollars to have made but everywhere i see pre made boards they are $70+ unpopulated. For $100 I can get one populated with everything bar the LDMOS. nice work on the transformer. I also considered this but with brass tubes. What is the difference / best between copper and brass in the transformer design? Thanks. Another question about tuning for different bands. I see people add low pass filter boards for various bands but if you only want to mono-band what is the equivalent part to tune. It is simply an air choke and capacitor mounted directly to the LDMOS board or you always need to add an external bandpass filter if Mono-banding?

Nice calculator.

I'm just worried that if I build one of these that one day I will forget the radio is at 100W. Thinking to put a 10db attenuator in the amp and try to run the radio between 10 and 30W Apparently i need up to 3W to drive a BLF188XR. I was recently thinking to build a really big dummy load. I found rf resistors that have two leads like these attenuators. I'm guessing you can use then as attenuators or dummy loads if you connect the final pin to ground. The idea was to build a 3x3 or a 4x4 grid of them or use high power 200 ohm rf resistors and just put 4 in parallel. does anyone know what the difference is with these RFR components example an RFR50-250 with two leads? Is it just a dummy load resistor or is it an attenuator or are they one and the same. Thing is they don't have a value for attenuation, only power and resistance or is it impedance the value on an RF resistor like this with two leads?

Hi. Are these still available?

Your math is incorrect

A great series of videos and I learned a lot... and I'm going to buy you a tripod for Christmas! LOL

Very informative! Thanks for this fantastic video! Keep up the great work! ~ 73 ~ AC7WH

Would it be possible to use an N-way Combiner if one coaxial wire has 75 ohms impedance and two other wires have 50 ohms impedance?

0:35: ⚙ Overview of designing a push-pull RF amplifier using IRF 510 MOSFET. 5:35: ⚙ Discussion on designing RF linear amplifier, including input and output board calculations and testing. 10:20: ⚙ Designing RF linear amplifiers involves reducing parasitic effects, increasing bandwidth, and ensuring gate bias and stability. 16:09: ⚙ Overview of RF linear amplifier operation classes and biasing techniques. 21:30: ⚡ Importance of impedance matching to prevent power reflection and transistor failure in RF amplifiers ⚙ Overview of designing a push-pull RF amplifier using IRF 510 MOSFET. 00:35 • Discusses the push-pull circuit topology and IRF 510 MOSFET usage. 00:35 • Focus on input and output boards design, with emphasis on cost-effective components. 00:42 • Emphasizes the affordability and historical usage of IRF 510 MOSFET for experimentation. 01:07 ⚙ Discussion on designing RF linear amplifier, including input and output board calculations and testing. 05:35 • Calculation of output impedance, transformer ratios, and RF choke impedance. 05:35 • Bench testing for output power, gain, efficiency, SWR, harmonic distortion, and low-pass filter purpose. 06:10 ⚙ Designing RF linear amplifiers involves reducing parasitic effects, increasing bandwidth, and ensuring gate bias and stability. 10:20 • Shunt resistor used to reduce parasitic effects and increase bandwidth of Transformer. 10:20 • Voltage divider with resistors, zener diodes, potentiometers, and chokes used for gate bias of mosfets. 10:57 • Mosfets are voltage devices with a threshold for current flow above a certain voltage level. 11:37 ⚙ Overview of RF linear amplifier operation classes and biasing techniques. 16:09 • Class A and Class B operation offer higher linearity but lower efficiency. 16:09 • Class C operation provides higher efficiency but lower linearity. 16:38 • Biasing the transistor involves adjusting the gate voltage above the 4-volt threshold for optimal conduction. 17:07 ⚡ Importance of impedance matching to prevent power reflection and transistor failure in RF amplifiers 21:30 • Increase in reflected power can cause excessive heating and transistor failure 21:30 • Impedance matching is crucial for both input and output sides to avoid thermal runaway 21:56 • Comparison of RF transistors like MRF 300 A/B and IRF 510 for push-pull applications Recap by Tammy AI

good educational vid. im off to play with elsie :-)

An excellent series of videos. I'll see if I can apply this to my circuit. I made a p.a. with two IRF50 in push pull at 12 Volts for QRP years ago and only just now watched this video. I based my design on other circuits I saw. It worked well enough using the island p.c.b. method of construction but power output went down at higher frequencies so I'm attempting to use RD06HHF mosfet's. IRF510 are good at lower frequencies, not too much gain and very stable and don't go silly at higher frequencies. And they are cheap to replace if you make a mistake! G4GHB.

Thanks RF man. Another good design example which I enjoyed very much.

Another excellent vidio RF man. Thx

Good stuff RF man. Thx

Great vid. Im about to purchase a couple QRP labs QMX + kits and the 10w PA. uses IRF 510. Now I will have a better idea of whats going on . Which hopefully means less smoke😶‍🌫😶‍🌫👀1 QMX will be standard, the other for experiments ,and driving the amp to 20w or so . Subscribed.

Just built a similar amp using the MFRX1K80H. The board design is somewhat similar from DXWORLD-e and the power going is 57v DC at 30 Amps. The output is 1KW. A 7-band Low-Pass Filter was included in this design. The transformers in this design are a 1:9 coaxial transmission line type of transformer from the LDMOS Drain Pins and then that is fed into a 1:1 coaxial transformer for the final output stage

Just completed the 6 part course. Absolutely fantastic. Reference grade presentations, clear and concise. Thank you very much.