If you remember from last post we had the power rail all wired up to the sockets. The next step is to connect the chips with the various capacitors, finish the audio out and start the Local Oscillator. You will see in the picture that I have fixed the power wire for the LM386 and it is now wired to pin 6 which is the proper V+ pin rather than pin 7. You will also note that indeed the power jumper created a small issue jumping from pin 6 and 7 of the NE602 over to the start of the local oscillator. A good foot note for future builds to think about that a little more. Other noteworthy lessons on this section are: 1. My canonical tip for my Weller soldering station is not a great choice for melting the Krylon and getting a good ground solder bead. Nor is my wet pad a satisfactory device for cleaning my tip. There is a significant delay in having a clean tip and being able to melt solder that is sufficiently annoying. As a result I went to Fry’s in Arlington, Tx and purchase an ST2 and ST3 soldering iron tip as well as a Hakko tip cleaning bucket. This definitively made the soldering process better!
The only other notable step from this section was that I purchased a bunch of alleged NP0 caps on eBay. They were shipped on the slow boat from China. When they arrived they looked like ordinary ceramic capacitors and in no way looked C0G or NP0. So I decided to try to test these out. I took out a 680pF capacitor and put it on my AADE meter. It was within tolerance of expected C value. I then pulled out my YL’s (wife for non-amateurs) hair dryer. I then kicked it on low and started heating up the cap. It went from a cool room to hot enough I preferred not to touch it. Total change is capacitance. 1 pF. I’m still learning, but that seems to be well within tolerance for an NP0 capacitor.
The audio chain only needs the actual 3.5mm jack. The LO only needs toroids and the final variable capacitors. Then I will start on the front end. This project is getting real!! Hope to have it make noise soon! When I do get it to make noise I will try to post video!