Some Technical Stuff

This page deals with updates and comments on some QST papers.  
  This section also contains unpublished information that readers have ask about.    By published, we mean things that have appeared a journal or book.  Who know about the Internet!    A section is devoted to articles to support Experimental Methods in RF Design (EMRFD), ARRL, 2003 (with KK7B and W7PUA).    A section at the end relates to filter design, including some quartz crystal related things.
Page Last Updated on April 23, 2021.

General Interest and QST Related Info:

Free Semiconductors from KE6F.      Bob has some BUZ104 Power MOSFETs as well as the small signal BF998 dual gate MOSFETs, and much more.
       For more information, just click here.                  
QST Spectrum Analyzer (paper in Aug/Sept, 1998, with K7TAU)        (18March2021)
     Also includes the tracking generator described in 1999 QST.
Hybrid Cascode IF Amplifier    (From QST.  Includes board layout info.)   
Progressive Receiver PC Layouts   From QST and some ARRL Handbook editions. 
     This is not a discussion, but is a collection containing the PC board layouts.   These are the boards originally designed (by K5IRK) that were used in the original QST receiver for November, 1981.     The boards have been sold by some manufacturers here and there, and may even still be available.     However, the folks selling boards no longer bother with the template information.    These are old, single sided boards, but they worked for the PR.

EMRFD Related Stuff:

Listed here are a few articles in support of the ARRL book (with KK7B and W7PUA),  Experimental Methods in RF Design.   
Transformer Coupled LC Bandpass Filters     
The Incidental Multiple-Tuned Circuit     
Another Look at T/R with QRP Transmitters      
A Low Noise 50 MHz Amplifier.   A practical circuit using a BF998 SMT dual gate mosfet.  
Small Signal Amplifier Design    
Three articles (mildly mathematical) discuss small signal bipolar transistor circuits.   The three articles are:
      A Termination Insensitive Amplifier for Bidirectional Transceivers (with Bob Kopski, K3NHI)
      The Feedback Amplifier with a Simple Model      (This is the math in greater detail for the other two articles.)
      Transistor Models and the Feedback Amplifier     This one includes some measurement data.
     An Audio Feedback Amplifier for DC Receivers 
  a.k.a.  AFTIA       (New April 2021)
Bypassing and Decoupling--Thoughts and Modeling      

Some Unpublished Stuff:
These are things that I thought might be of general interest.   By "unpublished," we mean that they have not appeared in a paper magazine or journal.

The Two Faces of Q.     
    This is a discussion about the Q of LC resonators, and the Q of the individual L and C elements.  We normally measure the Q of a complete tuned circuit.   This is the result of the Q of both the L and the C in that circuit.   This report discusses the measurement methods that can be used, the way the Q of L and C combine, and some measurements we have done on a variety of components.  A variety of measurement tools have been used including a HP4342A Q-meter.  
Almost Synthesis      
       This is a discussion of a frequency synthesizer built to control a traditional superhet receiver or transceiver.   It is a one-on-one PLL design, so the phase noise performance is reasonable.     Additional features make it handy for general purpose applications.    No special ICs are used, and it is dirt cheap.     This is not a "DIY" type project to be copied.  Rather, it is a report about an experiment that we did.  
dB versus dBm     This is a discussion of the mathematics related to the decibel.   (We think that the math does matter.) 
JFET101    This tutorial examines the junction field effect transistor, starting with a simple model of a piece of silicon.    After discussing the behavior of the element, it is applied.   First, biasing is presented.    Then some amplifiers are designed.     

Extract scattering parameters in a SPICE analysis.    This is an old one that continues to be requested.    

Filter Design and Crystal Things:
9 MHz Filters with Inexpensive Crystals    
What's this 30 pF Stuff?      

An Oscillator Scheme for Quartz Crystal Characterization    
Designing Narrow-Bandwidth Ladder Filters      

Spoiler Alert:   This report is a general discussion that is long and is full of equations.
Retuning Meshes in a Lower-Sideband-Ladder Crystal Filter       

Simple Quartz Crystal Models:  A Review          

Mixed Form N=3 LC Bandpass Filter Design Equations   
Practical HF Bandpass Filter Tuning

    This takes one past the computer design.  After the design, you alter values, insert trimmers, and tune.  This tells one how to do it.