One Watt, a ton of fun..Phase One

This post was rescued from my original original blog. It's when I caught the One-Watter building Jones. That was a little radio designed by Diz, W8DIZ, of Kits & Parts and CHuck Adams in support of a code practice course Chuck was doing for folks in Arizona (or so I am told). The idea was to build this litte one watt radio tha the students could take to class and practice sending to one another. Good in theory but the fact was that they were getting some pretty decent DX with the radios and, soon, Diz made the kits available to the hamming public. I fell in love with them after I bought and built my first one for 15 meters. Soon, I was on to a 30m, then 20m, then..then..then 160m! They had a VXO that covered 2 Kc around the various bands' QRO CW watering holes but the rigs grew so popular for the 20m band that Diz developed a "stretch" version that covered from 14.000 Mc to 14.060 Mc. Still have a stretch kit on the shelf plus 40m one that go along with the other kits I stocked up on prior to my retirement in October 2017. Anyway, on to the show..

Started out this project by organizing my work area to implement Chuck's methodology. He likes to mark a full-page schematic as he installs parts and I opted to do the same. In addition, Diz's kits uses the infamous 1/8th watt resistors and my eyes are becoming too feeble to discern colors -- even to the point where my magnifiers will not help. (See the problems I had with the resistors in the Sawdust Regen kit in the previous post.) Consequently, I found the cheapie Chinese component tester I got some months ago to be an indispensable tool for identifying resistors. Guessing that device will never leave my side for future projects.

As Chuck explained in the video above, Phase One consists only of ensuring that 12 volts negotiates the reverse-polarity 1N4007 diode and arrives at the proper pin of the LM396 socket. Also, the LM386 audio amplifier circuit is checked out to see if it working. I was skeptical of this because of my experience with the QST version of the WBR regen receiver and Chuck's comment about the speaker volume being faint. However, I was pleasantly surprised that the circuit provided a lot of volume and am led to believe that the unit will be perfectly suitable for unamplified speakers when put into operation. Pictures below:

Workplace. Not as gloomy as it seems just the flash didn't fire. Note component tester.

Phase One completed with audio circuit.

Audio section.

Radial 100 nF cap substituted for 100 nF SMT cap at C36.

Close up of same. Solder flux has been cleaned away. Cap will be lain flat when board completed.

Phase One schematic progress. Note R12 installed to facilitate C36 replacement.

I would add these notes to my Phase One effort: pay special attention to where Chuck says to go ahead and install ALL of the the SMT caps first if you want to. He mentions it and I pestered Diz who confirmed that installation of same would not adversely affect the "Build and Test" paradigm. Also, note Diz's correction in the addendum (and my pictures above) wherein he recommends NOT installing the C36 SMT cap but rather putting in the axial cap from one of the C36 pads to ground. I asked Diz about this and he says that there was an error in the PCBs dated 09/03/2015 ~~ see the "20150903" below the DC connector holes in the upper right. To quote Diz:

Hi Bill,

Take a look at C36 on the schematic....it connects from ground to the gates of Q8/Q9. Now look at the PCB...it connects C36 from the gates of Q8/Q9 to pin 4 of U4.

The PCB is in error...also known as a royal screw up. Easiest way around the error is to solder an axial 100 cap on the bottom of the PCB. The PCBs is error are silk screened with 20150903.

See http://kitsandparts.com/1watter15u.php

Any PCBs after 20150903 are corrected.

See http://kitsandparts.com/1watter30u2.php

73, Diz, W8DIZ

Parting comment on the LM386 audio amp circuit: I had a spare LM386 N3 rattling around on the bench from my WBR effort and plugged that in when doing Chuck's audio test. (I was too lazy to go rooting around in the kit parts bag.) The audio -- with headphones -- was more than adequate. When I swapped in Diz's kit-provided LM386 N4, it was almost ear-splitting. Again, this leads me to believe that this little rig will perform just fine with in a room with a speaker -- provided the room is not Carnegie Hall.

Anyway, all seemed to check out just fine. On to Phases Two and Three.