Slug tuned SW Superhet radio receiver pt 2: reception results and schematic of the Local Oscillator

Second experiment regarding the slug tuned Shortwave Radio, working between (say) 3 MC and 10 MC. For reading the precise schematic: go to 1080 HD on YouTube.

I show the schematic of the local oscillator and some good reception results. Location: Netherlands, 7 October 2025, around 22.30 hour in the evening.

In the dawn/dark many SW radio stations pop up, both from Eastern Europe but als from very far away. On a 4-5 meter indoor wire. Or a 10 meter outdoor wire, connected to the top of the antenna coil (slug tuned) via a capacitor of 14 pF (picoFarad).

Talking about the local oscillator in a Superheterodyne radio. The waveform must be very pure (a sine wave). Problem was that, when I used a parallel tuning capacitor, the waveform of that local oscillator got deteriorated (lot of jitter). So my idea was to avoid that: use a series coil (not a parallel tuning capacitor) to get to the right frequency bands, they are visible in the video. That is why the L.O. is made “as it is”.

One series coil (in series with the local oscillator coil, the orange: 8 windings, telephone wire, 1 mm plastic diameter, 0.4 mm massive copper inside, form is paper roll of 1.7 cm, sliding over standard yellow pvc electricity pipe of 1.6 cm diameter where the ferrite moves in-out) is made with 2 Ali coils in series (visible in my video “goodies from Ali”). Via one of these series coils (ferrite core tunable, brown form) I can align the local oscillator in the low frequency range (say: 3 MC-5 MC).

More in the schematic & the video. Can be tested with an oscilloscope and a frequency counter.

The other “series” coil (for the 5-10 MC range) is wound on the same form and consists of 4 windings (blue wires, same type). It is in series with the 8 windings coil. The “node” goes to ground, minus (-).

In both cases (low or higher frequencies on SW) the ferrite rod (for tuning to radio stations) moves in and out. To get to all SW radio stations between 3 MC and 10 MC. In this case. The whole idea/concept can be adapted for MW and LW.

Perhaps this sounds “problematic” to make. But it is very easy. You need basic things: tin plate, multiplex wood, glue for sewage pipes used as HQ electronics laquer, brass pins, some isolated wire and 2 (round) ferrite rods of say 8 cm length and 0,8 cm or 1 cm in diameter. And standard PVC pipe and some cardboard. It is fun to make it. That is (of course) my idea.

In this video the 455 KC IF (intermediate frequency) amplifier with its “mixer” (= frequency transformation) is not showed.

Only the L.O. is showed, because of its importance. The HF antenna amplifier 3-10 MC was already showed in another earlier video.

I will publish the whole and complete schematic of this SW receiver ASAP. But have to do some more experiments regarding the IF amplifier and the antenna coil, 3 MC-10 MC.

By the way: there are many usable IF amplifier schematics, earlier published, on my YT Channel. You can find them via my Channel Trailer (Radiofun232 on YouTube) and then via the “looking glass” = the search option. Search words: IF, intermediate, intermediate frequency, 455, 455 KC, IF amplifier, etc.

Interested in certain electronic circuits? (Radio’s, audio amplifiers, audio pre-amps, audio filters, measuring devices to test transistors and (say) mosfets or (radio) coils or Shortwave and MW radio’s? Go to my Channel Trailer (“Radiofun232 on YouTube”).

Type there the keywords that you like (e.g. radio/audio / amplifiers / filter / Shortwave / Short Wave /test / testing) into the “looking glass” = search function” and give “enter”. Via that you can find specific video’s (under the say 1700 published).

In almost all video’s a schematic is showed, if so: it is a working and well tested electronic circuit. Keywords (again): ”audio”, “radio”, “amplifier”, “filter”, “Shortwave”, “transistor”, “FET”, “oscillator”, “generator”, “switch”, “schmitt trigger” etc; so the electronic subject you are interested in.

My books about electronics & analog radio technology are available via the website of "LULU”, search for author “Ko Tilman” there. Or https://www.lulu.com/search?adult_aud...

I keep all my YT videos constant actual. Search on YT and avoid my circuits that are republished, re-arranged, re-edited on other websites, giving not probable re-wiring, etc. I take distance from all kinds of fake claims, made via republishing my circuits via the www. Thanks for watching. Upload 7 October 2025.

Relevant earlier video’s

Part 1 of the project to make a slug tuned SW radio (5 october 2025)
   • Slug tuned SW Superhet radio receiver 3 - ...  

Thinking about that new radio approach (slug tuning) 3 october 2025
   • Exper. SW radio. A new approach, tuning th...  

HF Antenna amplifier for Shortwave (26 sep. 2025):
   • HF antenna amplif. for Shortwave 1-10 MC w...