Summary List of Tools
1. Web Links
2. Our Make a Frequency Stable L-C VFO notes from 2014 - 2024 : pdf file
3. Our Gilbert Cell Mixer notes from 2023 : pdf file
4. Our old x86 Windows GUI NPN Bias application : zip file
5. Gilbert Cell Mixer MAX268X series:: FDIM 2025 - Jason, NT7S : video
6. SRF of Common Bypass Caps + What do I use for 3.5MHz or even 1.8 MHz? : graphic
1. Web Links
Marki Microwave LC Filter Design Tool
W7ZOI Website
Iulian YO3DAC-VA3IUL's web site
Steve, VE7SL's blog
Bettina Neumryr Popular Youtube Channel - building circuits from old magazines
Applied Etherics -- NT7S on Substack
Ken Kuhn's website
Jim's Radio Shop
2. Our Make a Frequency Stable L-C VFO notes from 2014 - 2024
The notes = a 6 page pdf file. Mostly discusses the temperature coefficent of VFO parts to hopefully help builders get a little more frequency stability if they choose to make an ancient/vintage Inductor + Capacitor (L - C) Variable Frequency Oscillator.
Click to download LC-VFO-Notes.pdf
3. Our Gilbert Cell Mixer notes from 2023
By request. Happily, we kept a draft text document of Part 1 of our former blog post that got about 7K views per month in 2023. This version lacks our minor edits-over-time + nicer 'Blogger' formatting -- and Part 2. Part 2 featured some example-concept, discrete BJT mixer designs. The file notes = a 16 page pdf document of our raw notes with figures. These notes were even referenced in a successful doctoral thesis by an Asian PhD scholar.
Click to download GilbertCell.pdf
4. Our old x86 Windows GUI NPN Bias application
Above — A screen-shot of the Bash version of NPN-bias running in the terminal. I work on it from time to time (have added printing for example) -- and plan to add some AC small-signal analysis.
5. Gilbert Cell Mixer MAX268X series:: FDIM 2025 - Jason, NT7S video
6. SRF of Common Bypass Caps + What do I use for 3.5MHz or even 1.8 MHz?
A tale of 2 capacitors: Sweep of a junkbox leaded 390p -- then the regular leaded 390p Vishay capacitor we stock. We do not have any special high Q caps in 390p -- but have them in some other values. A high-Q version (usually expensive and SMD) may give an additional 10-12 dB depth in the notch during a sweep. Also as you move into high VHF + above, employing double-sided copper clad boards tends to boost the depth of the notch.
