On Wed, 17 Mar 2010, kb8stb wrote: > I have an MFJ 269 (i know its not a "precision" instrument...) but at > the hobby level is there any reason for me to think about building > this thing? > > What does it do (even the $498 one) that my 269 dose not? (ignoring > the precision issue) > > I ask in hoping to learn something more about radio and test > equipment.
I figured out quite by accident one night that an MFJ-259 and a directional coupler can be used with an HP-141T to simulate a tracking spectrum analyzer. By using the analog storage function of the scope, you can verify what the output of the MFJ-259 is when feeding the directional coupler into a dummy load. Then reverse the directional coupler, and the sweep should be flat and low-level if there is a dummy load on the coupler. Finally, you attach the antenna or other device and look at what power is reflected. I had the benefit of being able to do this in a number of different ways, using an isolator shelf with a 250W dummy load, -30dB directional coupler, and my other directional coupler of unknown rating. -- Kris Kirby, KE4AHR Disinformation Analyst
