Archive for the ‘LTSpice’ Category

Short Update…

July 3, 2014

Wanted to mention what I found by comparing the molded inductor verse the use of a toroid for the RF Phase Shift.

Found that the molded inductor (molded inductor for the primary and four turns of hook-up wire for the secondary) has at least a 10 dBm loss at 7 MHz. I wound a toroid for the same component with ten turns for the primary and four turns for the secondary on a FT37-61 and had only a 2.8 dBm loss at 7 Mhz. So, using the toroid is the better choice. But, modeling this new insight with LTSpice still leaves me with some doubt. The RF level going into the Detector stage is still not up to 700mv which I think would be necessary for good sensitivity. I doubt I will continue on with this project in its present form. Still have some desire to use the LO ceramic osc and hook it up to a homebrew NE602/LM386 receiver I build a few years ago to see if that would work.

Have discovered some really interesting functions for LTSpice…things I wish I had known years ago.  Still learning how to set-up sources for driving oscillators, mixers, etc and what types of analysis’s tell me what type of information. This learning has turned out to be more fun that I first imagined!

With the fourth just around the corner, I doubt I will get much done till next week. I have started to do the 30 meter mod for my KX1 and also want to do the auto tuner kit while I am in the kit building mood.

Hope everyone has a good and safe Fourth of July weekend!

72/73…Mikey, WB8ICN

Time to Relearn a Few Things!

June 25, 2014

Been trying to use LTSpice with the binuaral receiver project. What I have learned is I am quite stupid when it comes to modelling a stage and understanding what is going on (using LTSpice). I have pestered a very patient friend from down under and I decided this morning that I should be able to answer some of the questions I have been throwing his way.

So, for the near future, I need to get a better handle on understanding and using LTSpice … then I can go back to modelling what I am doing before snuffing solder fumes. There is enough tutorial info out there on the web about LTSpice and how to make the best use of it…and I need to learn (relearn???…now I am wondering how much of it I learned the first time) LTSpice from a homebrewers point of view and how to make it a useful tool for  me.

This is rather embarrassing to admit, but it is the truth and I really want to be able to use it (LTSpice) the way others have come to use  it and learn from it.

Mark, again thanks for some really important “learns learned”!

P.S. – I can now model a VXO with some success!