If someone wanted to build one of these amplifiers for the 160 m handbag, or lower, let's say one mhz. How would you calculate the input impedance. As it's not stated on the data sheet. A significantly lower frequency, I would assume it causes a gain increase in the f e t. But also the inductive capacitance would vary. So how would one actually calculate this?

I ask Dave question : what govens the height of the antenna off the ground at different Frequencies ? By the way Dave cannot tell me

Question: what wire antenna thickness that restricts maximum RF out put from transmitter be it 50 watts output?

this is very good video, explanation and direction are easy to follow. Would it be possible to screen record your simulation in the future? God bless

This is a very well explained and produced video, thank-you. I shall watch the rest of the series now.

How did you choose the values for the tuning capacitors in the output transformer?

You can use 100V 50A TO220 pkg, dual diodes (in parallel) mounted on a heat sink. I have 10x1200 W SMPS in parallel. Works great. I have only ever loaded it to. 800 amps.

Fantastic video RF Man with plenty of usefull information. I have seen all series again and again in order to adapt your way of thinking and desighn. Thanks for your efforts and will to explain in such depth. Few questions, Are both Mosfet N type as in drawing or one is P type. Do the mosfet source :see: real ground? or the entire pallet is lifted? In order to be excited how does the gate founds a ground in order to close circuit? Thanks again 73

Congratulations. Your videos are master classes. They have allowed me to understand perfectly how an amplifier works. Are you going to post videos again? You are awaited with great interest.

Vey good !

Nicely explained. Very clear. Thank you.

Hello friend, where can I get these cores? I'm from Brazil, I search for which model on AliExpress, I would really like to learn and try to do this project, thank you very much!

Well I'm glad there's more to it because I was worried about getting all this in on video!

Nice video 🎉

If they're worried about core saturation using 43, just add more ferrite by using a larger core. I never use 61 in the HF range.

excuse me sir for my ignorance but does it work with an analog TV VHF modulator? Thank you in advance!

What would be the advantage of this splitter vs standard Wilkinson divider with transmission lines changed to coaxials. Resistor is needed as well this circuit has longer cables (wilkinson only lambda/4 length). Thank you interesting topic covered

What type of PCB material is this? FR4 or Rogers, PTFE etc ? I kinda assumed that ordinary FR4 was not so good at VHF

Just came across these videos, as a young buck 21 years old I can’t explain how much these videos will help me, I’m a diesel mechanic by trade but have been into cb for 2 years and have been wanting to build my own ldmos amplifier. But the learning curve just in terminology has been huge for me to overcome

It is really helpful for beginners, very clear explanation.

Realizé un "hybrid splitter" similar con núcleo binocular y cables corrientes.Necesité añadir condensadores en al salida de 25 ohms, pero funciona perfectamente.Supongo que es por falta de la capacidad del cable rg-316. También el combinador funciona de maravilla. Video útil y muy bien explicado. 73 's

Are the feedback resistors non-inductive? I would imagine that would be quite important for stability. Most film resistors seem to be spiralled and so slightly inductive. I wonder what you use?

Great and informative thank you! 73

Less noise in ring mixer

Wow I really like your video and is very interested

When designing these, I've always said there's a small bit of voodoo involved over stray inductance and capacitance over the layout. After doing the impedance calculations, the circuit should still be tuned, generally by a padder cap. You can get it close after the calculations, but layout and parts placement helps throw a wrench in the gears, so to speak.

TERRIBLE CAMERA WORK, motion sickness plus

Since both IRF510s present a 50ohm impedance would that mean the transformer would see a 100ohm impedance or since they are 180 Degrees out of phase they present themselves as one at a time at 50 ohms total?

Been playing with this design for sometime with pretty good results especially with a Pi LPF to reduce harmonics. However I was never able to get the 2 devices to work good with 1 xformer. Great video.

Thanks for another great video! 785

Another great video!. I always enjoy and learn alot from your videos. Quick question: The 2:1 auto transformer, the way I am looking at it might be wrong but I see it as a 4:3 turn transformer with an impedance ratio of 1.78. Is that correct? Thanks 785

I really like your technical explanation! Great video. 785

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Loving your videos. The overview of the individual sections is quite easy to understand. Are you able to tell me where to look for LTSpice models of the LDMOS fets? I'd really like to model the circuit for better understanding. I hope you can help.

You could build all this into a metal box with SO-239 sockets and an external RCA jack for keying, for a fifth of the price!😲

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

Great FB thanks 73 HANZ YL3JD

Sir, can I limit the output current of each boost converter to a certain amp, lets say I set each of their current limit to 10amps, and if the load draws 10amps, the first boost converter will do all the work, but when it draws 15amps, the second converter will kick in to contribute to the load sharing, and use shottky MBR60100 in each converters output to isolate them, this way with the shottky diodes the voltage drop is minimal compare to that of the resistor. This set up uses the second converter as a back up if the first one reach its current limit, this way Im not pushing the first conv. to its limits. Am I making sense?

So you basically have built a CDN for the DC range of under 10GHz😂great👌😎

Agreed. The LPF is indeed part of the amplifier. Anyway, the harmonic content of push-pull amps will be low in 2nd harmonic so the highest will probably be 3rd which will likely be around 20dB below fundamental. So the sum of the power in all the harmonics should be significantly less than 10%. Not really significant. Agreed in the two-tone test. Only way to test an ssb amplifier.

shortcutting sections of the inductor, it increases losses and lowers the quality factor

I've been struggling to understand the theory behind this for a long time, this has cleared up many things. Looking forward to watching the rest now, thank you!

Good job OM! Vy 73's

Thank you!

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I don't think that was a correctly am modulated signal to start with.

Hi, do you do custom work? I am looking for a fully built RF amp focused on 470-490 mhz. 3-5 watts. 12-15v dc. Do you have anything like this? Thank you, V

Hi RF Man. Thanks for these videos! I am seeking an RF amplifier that can input 250mw and boost to 3 watts+. Frequency range is 470-480mhz. Do you have any recommendations? Do you take on custom work? Thanks!

Your clear and concise explanation has allowed me to get a useful start to understanding and using the Smith Chart.. I am also in need to build an L network for a remote tuner so this is priceless information you have presented. GOD bless your Sir!

where do you probe at?