This is a repost so all VXO material is in one place to get at.Mon, 02/22/2010 - 09:57 - wb8icn

While cleaning up some old doc's and notes last night, I ran across my copy of the 1999 FDIM Proceedings. George Dobbs3RJV had did a presentation detailing four small QRP projects for an evening or weekend, to include a Universal VXO (page 61 - 64). Reading through that article turned on a huge light bulb for me explaining why (or at least acknowledged that it is a reality and practical possibility to attain large swings) I was seeing a large swing on my 80 meter VXO project.

First of all, I love how George writes and speaks...a Master in His Own Time! Anyway, George commented that DJ1ZB had wrote in one of the G-QRP Sprats that the in-series inductor with the variable cap and xtal in a VXO circuit can be improved by breaking up the inductor into two nearly equal value inductors to be laid side-by-side for interaction. This allows for interaction which in-turn produces freq swings well beyond the normal swing for a VXO. Nothing was said about using two xtals, which I did, so maybe there is a lot of promise in this endevour. I sit here watching yet another 5 to 8 inches of white rain coming down, so great day to snuff some VXO fumes and see how the following might be useful ... or not.

1. Two xtals in parallel and series

2. Using molded inductors (so far that is what I have used), but then try wingding some roids to redo the test using ferrite/iron powder

3. Does the oscillator circuit, the use of a 2N2222A, or 2N4401, etc, makes any difference in the amount of freq swing

4. What is the drift, stability, and noise associated with a Super VXO

OK, enough for now. Time to get a quick letter out to my youngest daughter who is now in Navy Boot Camp and also get my wife's morning cappucino made...I have lived in a house of woman all my life, so knowing the rules allows for lots of shack time!!!!! My hat is off the ladies of my life. All of them have served or are serving in the US Military for all the right reasons...I have tried to talk each of them out of it just to be sure, and I saluate each of them. I suspect I should have enough info to write up a nice article for the MI-QRP Club's quarterly mag called the T5W. Might also send it on to BBQ as well.

72...Mikey, WB8ICN