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Welcome to VE7CA's Design Utility
Users Log in to Design Utility This is a link to a Radio Design utility that was developed by a friend. He is making it available to those who come to my site. At present you need a password to get in. Send an e-mail to:  requesting a password. Other pages in this section like
"Design -> Tools" provide help for some design situations without a password.
This RF Design Program is a tool that an amateur radio experimenter (homebrewer) should find helpful. When I started building the HBR2000, I was looking for something to help select component values when designing a VFO for a certain tuning range, bandpass filters and impedance matching circuit component values etc. I wanted a program where I would stipulate that parameters, such as: tuning range of a VFO or type of Filter, BW, Centre Frequency, how many sections and estimated Q of the coil etc. and the program would do the calculations based on the inputted parameters as well as produce a graph showing insertion loss in the case of a filter design. My friend had a program for design which I have found indispensable. We added and modified it during the development and continue to add new features when needed. It is very easy to use. The program was not intended to be marketed thus it does not provide extensive instructions. It is just a tool so if you are not familiar with some design techniques, you may have to do some research first. It doesn't teach, it calculates and analyses commonly used circuits in Radio Design. I used it extensively for my designs. Outlined below is a brief set of instructions to get started: Design Utility Tutorial : A BAND PASS FILTER To design a Bandpass Filer (BPF), in the upper menu bar select "Tank". The next page will have several white boxes already filled in with numbers. You can change the numbers like the BW or Fo (which is the centre freq. of the BPF) but for now just leave it the way it is and over on the right hand side click the gray button that reads "Calc". When you click on Calc, the program uses the numbers filled in the white boxes on the bottom half of the window to calculate component values displayed in the top half. Now click on "Anal". This instructs the program to send the information that was just calculated to the Analysis window. Now click on "Analysis" on the top menu bar. This takes you to the Analysis window where you will see the component values for the BPF you selected and in the lower part of the window a place to select how you want a graph to be displayed. Move over to the lower right hand corner and tick the 3 check boxes that say Ena Q, Log and Graph, then select "AppQ" (which means apply Q) and click "Go" then select "View" and click "Go". This will bring up a "Graph" page showing the component values, a circuit diagram of the BPF, a description of the filter and below, a graph showing the filter insertion loss in blue and the return loss in red. This can be printed and you can put it into you files for future reference. Select "Help" to get help with all the features of this page. The beauty of this program is that you don't have to be an electrical engineer to design sophisticated RF filters, etc. You decide what you need, input the parameters and the program does the calculations. A unique feature of the RF Design Program is the ability to vary the overall Q of a filter or matching network to allow the use of standard manufactured component values. Typically in a filter this would be the capacitors. In the "Tank" page you will notice a little box in the lower left hand corner that is labeled, "Zrat" (Impedance Ratio), and the number in the box is 10. If you change 10 to 9.5, and check the box next to it, you will notice after clicking on "Calc" the values of the components above the circuit of the filter have changed. The capacitor value in parallel with the coil changed from 910 pf to 1000 pf which is a standard manufactured part value (so is the 910 pf), but the point is that by making slight adjustments to the BW, Fo and Zrat values, you can often produce a filter that uses mostly standard value components. There are many other features that will become apparent as you begin to use the program. Good luck, good homebrewing and let us know what you think of the program. |