Frequency tuning FET oscillator on Shortwave 9.1-9.9 MC by changing the supply voltage

The video shows the effect of the supply voltage (2-4 V) on the frequency (range) of a Shortwave FET oscillator, made with a BF245 FET (can be a, b, or c type).

The frequency changes (very) substantially, which means that you can use it (in principle, when it is stabile enough) in a Superheterodyne radio SW receiver to tune in at radio stations in a (say) 800 KC or 400 KC frequency wide band (e.g. in the 7 MC or 10 MC band).

Tests about the stability still have to be done, but the circuit (when made in a physical stable way) looks (my insight) good enough to be used as local oscillator for simple SW radio’s.

And: the circuit can be a source for further radio experiments when focused on stability etc. I invite radio amateurs to do more experiments with this (principle) setup (and know that it takes much time & effort).

In general:
2 V - 4 V: 9.1 MC – 9.9 MC (800 KC bandwidth), pure sine wave form, 7 wdg. tank circuit (video gives more info about how to make the coil) with a 18 pF parallel capacitor.

2V- 4V: 7.5 MC – 7.9 MC (400 KC bandwidth), sine waveform (somewhat or more) distorted, 7 wdg. tank circuit (video gives more info) with a 140 pF parallel capacitor. Watch the video for the distortion (type).

The output amplitude of the oscillator differs from 2 Volt to 4 Volt, both in the 9.1-9.9 MC and in the 7.5 – 7.9 MC frequency band.

The waveform in the 7.5-7.9 MC frequency band is (somewhat) distorted, I want to make a next circuit with a BF 199 where this effect is compensated. In the past this was (in another circuit) succesful. I will try to cure both the distortion on that lower frequency band + the (say) to fierce amplitude changes when tuning over the complete band.

An amplitude change of 20 % is in general acceptable for a simple (= “steepness type”) SW 1 transistor mixer on Shortwave.

Final goal: a SW sine wave oscillator that can be changed within a bandwidth of (minimum) 800 KHZ in 3 (relevant) frequency bands on Shortwave between (say) 4 MC and 10 MC with simple 2 or 3 switches.

My You Tube channel trailer is here: https://youtu.be/xbgQ8T3oqh4
There are (some) links to my video’s on YT available on my Channel Trailer in the “comments” section. Select, in the comments section, always “NEWEST FIRST” to get the right overview. You can also search via the “looking glass” via keywords like ”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 from “LULU”, search for author “Ko Tilman” there.

https://www.lulu.com/search?adult_audience_rating=00&q=ko+tilman

Some of my books (not all) are available via Barnes and Noble and via Amazon.
But all my books (the complete bunch) are/is available on the website of LULU.

Regarding all my video’s: I constantly keep them actual, so the original video’s with the most recent information are always on YouTube. That is the source, and search there. When my video’s are reproduced or re-edited on other websites/channels you can not (!) be sure about the original content (=really working electronics with real properties for a purpose) and important adaptations to the circuits.

Be aware of that, I saw on the internet my circuits reproduced in a poor or not proper way.

I also found that people probably republish my circuits under phantasy names and/or with phantasy properties, attributing electronic properties to them that they were never made for, so phantasy properties. Sometimes they want to find gold with them. I take distance from all these fake claims; I cannot help that it happens, sorry. Upload 24 september 2020.

Видео Frequency tuning FET oscillator on Shortwave 9.1-9.9 MC by changing the supply voltage канала radiofun232