Trying to make a Long Wave Radio pt 6: make a measurement transmitter on 455 KC demo and schematic

Please read the textbox first. Properly working 450-460 KC measuring transmitter/IF filter tester is showed, schematic & demo, with only 1 transistor, the BC 547b. Correction: the "1N5" around the 1 K collector resistor means nothing, gum it away.

Background of the video: trying to make a radio converter to receive radio stations in the Low Frequency radio band, going from 150 KC up to 280 or 300 KC. Kind of project.

This is video = 6 of the series. I stumble on problems that have to be solved in a certain way during this “process”.

Say going from a TRF receiver to a superheterodyne or back to TRF (?).

Question mark, I see many Long Wave Radios on the www but do they really work? Made with “an old radio antenna coil”, a TBA 120 (originally made to detect FM, not AM) and many other strange schematics. Many circuits, I think, on the www were never made in reality or lack essential info.

Anyway…perhaps I am wrong. I know that the Long Wave radio band has very specific properties. You need super high Q coils.

Especially this one: a superheterodyne setup does not work "better", e.g has no better properties compared to the TRF receivers, say e.g. the setups of the classical time/clock radio receivers on Long Wave.

In case of a Superheterodyne we need an IF filter on (say) 455 KC with a bandwidth of (say) 7 KC or 10 KC wide. So that is a very sharp frequency range. Look e.g. on the www about the Murata filters, they show these properties (bandwidth- bandspread - etc).

So perhaps I have to turn back to the superheterodyne principle. That means that I can need an IF amplifier on (say) 455 KC with a bandwidth of 10 or 7 or 4 Kilocycles.

Could (perhaps) also not work in this Very Low Frequency Radio band. No guarantee, but I always show the best setups.

By the way: an IF frequency can/could also be on whatever other frequency, as long as there is no radio station transmitting on that frequency + the bandwidth of the IF filter is (say) 3 to 10 KC, at least to receive “normal” (10 KC wide say commercial radio stations) but also “not normal” radio stations, say 3 KC wide somewhere on “Shortwave”.

Problem of the “bandspread issue” is this: on higher (SW) radio frequencies (say above 9 MC) the “take out” of a radio signal (with a bandwidth of say 10 KC) gets more and more critical, due to the higher receiving frequency (radio wave theory, say when the radio waves “creep together” in physical terms).

Video 1 about this project is here https://youtu.be/gW8hZBa4sbo
Video 2 about this project is here https://youtu.be/flH--5q7zbw

More links in this video's.

There are more than 1200 Video’s on my YT channel. I only do analog electronics: audio amplifiers, analog measuring devices, radio circuits, many Shortwave radios, many oscillators HF and audio, other audio & shortwave circuits.

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