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Had a significant disturbance yesterday. K Index rose almost to 7 and was at or above 5 much?of yesterday. My guess is the ionosphere has a bit of a hangover.Chuck WD4HXGOn Sep 21, 2023, at 2:17 PM,

Without the inductor on the center tap, the instantaneous current transitioning from one side on to the other side on might have spikes on it, because turn-on and turn-off times are not mirrors of

Thanks John, I'd figured out that the envelope shaping would prevent an L(di/dt) issue at the start and end of transmission. But I was intrigued to know about the spikes at the current 'hand-off'

Ryuji, I address both types of switching in my note to Nick. My offer of a .asc file for simulation is for you, as well. LTSpice also has an FFT function built in, so the spectral content of any

I am testing a new antenna and I am noticing all my historical spots are missing? Has anyone heard what is happening? -- Colin - K6JTH http://tangokeys.com

JZ and Nick, I think there are two kinds of switching here. One kind occurs twice each RF cycle due to imbalance of the push-pull. Another kind is the keying envelope. I think Nick is talking about

Nick, Your thought experiment is correct. The topology is called a "Current Fed Push Pull Amplifier". It is frequently found in power converters. The center tap does experience voltage spikes as

My question here is not about balance or harmonic suppression.? I only mentioned the topic of 'balance' to point out that it does not mean that the instantaneous currents sum to a perfect DC. Equally

I forgot to add that there are a couple of LDMOS devices that are dual package for best balance in push-pull amps. Those are also for QRO amps.

As the AF pilots at Pope AFB used to say to their 82nd Airborne passengers: "We don't understand why anyone would want to jump out of a perfectly good airplane." To which the Airborne would

One way to summarize and simplify what you described is that, when a circuit's input-output function (time domain) is an odd function f(x) = -f(-x) even harmonics vanish. Now, what are the likely

Hans is too polite to quote "PoC||GTFO" :-) 73, -- Dave, N8SBE

Forgot to include the project name: "DE-9 Blank to SMA Bulkhead Conn for QRP Labs U3S" Chuck KB3ASW

I made a small PCB for my U3S with?the mounting?holes for the DE-9 connector and a hole for an SMA bulkhead connector. I have shared it on Osh Park where you can order it if you find it

While I have all bands back, it only puts out about 1/4W to a dummy load.? Time to start checking voltages on the board.

Can anyone verify that the QDX can transmit FSQ?

Not being an RF PA expert I’d be interested to know why the centre tap of the QMX RF PA output balun (T501) is not decoupled. I accept that the RF PA output is symmetrical, and thus ‘balanced’

i too would like details on how to build a QDX-M for 6 meters, also could not find call sign EX0AA in QRZ.? Please provide details on build for 6 meters. Thank you? 73 Emory? WM3M

Give a man a wattmeter, and he'll know down to the milliwatt how much power he's running. Give him two, and he'll never know how much power he's running... (with apologies to the time-honored saw

The above picture from the most recent assembly manual is clear to me.? The first 19 turns go between the Start and the 3rd hole, skipping the second hole used in the original design.? ?The end of