A Crummy Commercial

A couple of shots of Bob Hamel W9MO and before that, WB9AMC on Field Day: Bob operating phone on Field Day Bob operating the natural power station on Field Day (a hand cranked generator on the wall of the Evan's barn was to the left, out of frame) obits: https://www.jsonline.com/obituaries/pwix1053199 https://www.feerickfuneralhome.com/obituary/robert-hamel I remember the next summer after the Novice Quartet had been licensed: https://wb9kzy.blogspot.com/2022/05/the-novice-quartet.html Bob Hamel and Morrie Hornik (WB9JHW) had another set of weekly classes to get us up to speed for a General class license: code, theory and regulations.  The Hamel family was nice enough to allow us to inhabit their basement (where Bob and his Dad had their radio shack) those summer evenings.  And eventually that fall I went down to the Federal Building in Milwaukee and got my General.  If only they had followed with an Extra class ! (I was never a self directed learner  :) It all remin...

From yesterdays blog: https://wb9kzy.blogspot.com/2025/01/a-two-transistor-sine-wave-oscillator.html I retried keying the oscillator using the same trick I used before for the Wien Bridge oscillator: https://wb9kzy.blogspot.com/2022/02/wien-bridge-audio-oscillator-keying_27.html I shorted out the back-to-back diodes using a normally ON 2n7000 MOSFET: With the key up the gate of the 2n7000 is pulled high by the 4.7k ohm resistor to the positive power supply which turns the MOSFET ON and the oscillator OFF.  Key down then shorts the gate to ground turning the 2n7000 OFF and turning the 2 transistor oscillator ON.  It sounds pretty good ! roughly 7 mS ramp up/down times The CPO circuit uses about 1 mA key up and 3 mA key down at a 9 volt supply, 628 Hz. The circuit can be varied from 482 Hz (1250 mV p-p): to 1092 Hz (600 mV p-p): but I usually go with 600 Hz (1200 mV p-p): Very pleased with the result, was going to report it on the EDN site but it insists that my password is inco...

This is an interesting circuit: source: https://www.edn.com/a-two-transistor-sine-wave-oscillator It works OK: but I didn't have much luck keying it: The make isn't too thumpy but the break is clicky.  I just put in a 4.7K ohm emitter resistor on Q1 which stops oscillation.  A key closure shorting that emitter resistor will key the circuit (I also put in a series .56 uF cap) but the weird thing is that the minimum key time is kinda long.  There are probably other ways to key it but if things get too complicated it defeats the point of a simple circuit. The Peltz oscillator keyed better: https://wb9kzy.blogspot.com/2024/11/the-peltz-oscillator-again-as-shaped-cpo.html But it's an LC oscillator and the frequency is not easily changed - you can't have everything ! I'll keep looking - one of these days I'll find a simple circuit that keys nicely for a CPO and is better than my previous efforts. One other thing to explore might be using this basic multiple feedback ...

I was taking advantage of the ARRL Periodical Archive / Search, as mentioned before: https://wb9kzy.blogspot.com/2024/08/woo-hoo-good-news-from-arrl.html to look at old QEX articles.  This one by W6IOJ caught my eye: It is not so much that I am interested in PSK as a mode but I have a hardcopy of that QEX issue and remember that W6IOJ upconverted an audio signal to a low IF (think of those frequencies just above audible) to accomplish the PSK demodulation.  Now I know that working at frequencies roughly 10 times normal audio can have a lot of advantages.  If nothing else it can provide much faster response to changes in a signal.  This might be quite useful for Automatic Gain Control where a normal audio AGC may take multiple periods of audio before it can tame a sudden karge signal - hard on the ears!  Another application might be for tone decoding, again a PLL may need multiple audio cycles before a tone detection (lock) occurs.  The low IF idea could be ...

There was a request on an email list I subscribe to for a way to measure 50 uA currents without having to put a meter in series with the circuit.  The idea was to spot where the current was being used that was draining the battery too quickly. I thought of using an old, broken cassette player like this: (how was life possible before cheap phones that could play/record digital files?) - it senses the magnetic field recorded in the magnetic particles on the tape and since all currents have accompanying magnetic fields maybe a cassette player could be used to sense them ?  Of course since the current is DC the cassette playback head would have to be moved across the circuit board trace to register anything. I tried using a wire moved around a stationary cassette player head - no dice.  This was a fairly thick wire carrying 7.5 mA or 7500 uA so no chance of detecting 50 uA.  Thinking about it later anyone who has played a crinkled cassette tape knows that unless the tap...

I got an email from DigiKey today: And here is the fine print: So I checked and found it's been well over a year since I've ordered from them !  I did order a few times with Mouser in 2024 but the last DigiKey order was August 2023. So I will probably take advantage of that offer, basically just free shipping but still a good deal. Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm Update: later on that day I did place an order and got the $10 off, nice !

I was digging around in a junkbox and came upon this fancy Cross sleeved box: Opening it revealed the crystals I used with the HW-16 as a Novice (1972).   I think I got the 7050 kHz at AES, used it on mostly 21,150 kHz.  The aluminum crystal was a color burst from an old TV (I didn't have an 80 meter antenna, just used it for alignment).  The other 4 were my main 40 meter Novice band crystals - JAN didn't mark as well as Crystek so I taped the frequencies on the back: When I got my General I borrowed a Knight VFO from the Nicolet High School radio club, I didn't key the VFO so that was kind of the end of break-in for me as the VFO was LOUD.  Ah, the good old days !  :) Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm