Final VXO Results for VRX-1

Fri, 02/26/2010 – 19:11 — wb8icn

Final VXO Results for VRX-1

I ended up going with a series circuit just like Jason has in the VRX-1. I exchanged the 10uh roid with two 21uh molded inductors in series and physically laying side-by-side. I switched out the vari-cap with a 260pf vari-cap as this was what I had been testing with. I can tune with no issues from about 7.008 to 7.040 MHz. I haven’t started the interfacing to the NS-40 yet and it may end up being a case where a separate circuit is used…just don’t know yet.

I have some other ideas I want to try still…but wanted to get to a point where I could use the VRX-1 again and play, so this why I have installed this circuit first. If you were just to use a 40 to 44 uh choke, inductor, coil, etc, you won’t get the wide freq swing. It seems that the molded inductors when placed next to each other will interact and provide for some rather interesting results.

Why am I hung up on the use of a VXO instead of Hartly oscillator or DDS circuit? I can get a good freq swing and great stability using these modified VXO oscillators and parts count is only five or six…plus I can build it for less than a buck. Doug DeMaw, W1FB (SK) liked the idea of using a VXO verse other methods and now I see why. QRP is homebrew and simple methods for me. I like to be able build things up in a weekend and then play with it. I wish I had gotten more into the “KISS Homebrew” method sooner!!!

[What is KISS?  “Keep It Simple Stupid“]

72’s/73’s…Mikey, WB8ICN



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