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I don't have the time to explain this to the nay-sayers. Here's some good information about emitter resistors and bypasses. https://electricalandelectronic.quora.com/?__ni__=0&__tiids__=209157166&__filter__=all&__nsrc__=notif_page&__sncid__=71275531755&__snid3__=94954217899#anchor

It doesn't. It's the ratio of R10 to R11, both of which have the same value. That sets the AC gain. The cap allows it to have a different DC gain. It self-biases at 0.6 volts DC.

But with the given feedback resistors, it's running at unity gain. By your logic, just about any op-amp design should be an oscillator.

That's only possible for a gain of two or less. Unless you want an attenuator! fT is defined as the point of unity gain in a gaussian (6db/octave) roll-off. Oh yea. Like I really need one more project… :-)

As an RF Engineer, I've done dozens of such designs. This one might work a bit better with high ft transistors with some PCB layout tweaks, but I see nothing obviously wrong with it.

That's what bypass caps are for. I see several of them in the circuit. They need to be physically close to the high ft transistor. I'd rather have too much ft than too little!

R10/R11 and R13/R12 provide negative feedback. It appears to be set for unity voltage gain (1k for both resistors). I imagine the input transformer supplies needed voltage gain, and the push-pull output only supplies current gain. Regarding having the "wrong frequency" for the transistors...

I understand the rules, and wish to enter the contest. I promise to post an unboxing and plaster it all over social media if I win. ("PICK ME, PULEEEZE!")

Well, the first one I bought would put out 20 amps at 40 volts into a 2Ω load (800 watts) on a giant heat sink, pretty much indefinitely. Then, I ordered four more. Whenever I hear someone say "such devices" I know it means they don't have any experience with the specific device I was talking...

Try this. <—LINK That will give you 24VDC at 12A from 12VDC… at least, according to the specs.

I understand the rules and wish to enter the contest. I included a photo of my first "real" radio in my posting, for an extra entry. https://www.worldwidedx.com/threads/what-year-and-why-did-you-get-into-the-radio-hobby.270244/post-861212

My Dad painted houses and did remodelling for a living. People who could afford to hire a house painter often replaced "furniture" at the same time when they upgraded their house. So he would bring me home these big cabinet radios that had shortwave bands. They were often un-working, and I...

Subvert the dominant paradigm! I use a sixteen-year-old Mac Pro 4,1, mainly because it's UNIX underneath and it supports a wide array of commercial and open-source applications. Linux is fairly weak for running commercial applications. An open-source community keeps it upgradeable to the most...

I agree with most of what you wrote, but for someone who wants to experiment with antennas, I suggest an external automatic tuner. An internal tuner protects your final transistors, but may cause your coax to radiate under higher VSWR, and may result in high voltage on your coax. With an...

Did you know we're both going to be without hydro on Sunday, September 14?

No, I was on Salt Spring from 2006 through 2021. Cool! I got my US First Class Phone ticket when I was thirteen, but never worked in a station, getting a job at a shop repairing commercial two-way instead. My high school buddy (whom I took the test with) was station engineer at WQTE, Monroe...

Quadra? Never been there. I like islands. Used to live on Salt Spring, but it got too busy and expensive. Powell River is like an island — no road access. Glad 11 is working for you! I don't have an HF antenna presently. Going to put one up when the weather improves.

I don't have an HF antenna at present. I've got the materials, but the weather's been horrible. Soon!

I'm still using the Icom 735 I bought back when dinosaurs roamed the Earth. eBay says they're worth $250 and up, plus shipping, without power supply. You'll need 20 amps of 12-13.8 volts if you want full power out (200 watts PEP). The receiver covers 100 kHz to 30 MHz. You can mod it to...

There's a CME happening. MUF has come down below 40 metres.