Wednesday, January 24, 2018

Yet another resurrection..

These are some notes I made regarding a project I am proposing for a local repeater group in an effort to introduce new hams (so-called "Baofeng Techs") into the technical world of radio, electronics, and kit-building. Racking my brain for a simple project that might be of interest, I came up with the circuit below. It is the famous NorCal S1/S9 Signal Generator which was a kit produced by the NorCal QRP club many years ago that has since been discontinued. I am not sure of the licensing or other proprietary ramifications but, considering the time this has been out of production and the "modifications", I am sure this will qualify under the terms of "fair use".

Of course, it is a simple crystal oscillator with the option of switching between four crystals and between two output levels (S1/S9) and used for the purpose of aligning and adjusting the receiver sections of QRP rigs - or any receivers, for that matter. While it will not make immediate sense to Baofeng Techs, it offers the following:

(1) Kit building experience.
(2) Parts identification.
(3) Soldering practice.
(4) Assembly checkout.
(5) Introductory education to crystal oscillators.
(6) An end product of use in checking/aligning a receiver.

Herewith is the original schematic:

The original kit used SMT parts but I will not do so for this one for obvious reasons. Through-hole parts are easier to work with for beginners and I can source most of them from my junk box. But I do propose to create a PCB to simplify the build. The art here will be to generate the PCB and I hope to do so by following int he footsteps of Chuck Adams, K7QO, who is leading his doughty band of QRPers over at QRP-Tech on the email list. Chuck has found a few Chinese board houses who will generate PCBs for a shockingly low fee provided you send them the Gerber files. He has done this with the 25th anniversary build of Wayne Burdick's NorCal 40A transceiver, his Colpitt's Oscillator Crystal Checker circuit (see my earlier "Looking for a Perfect Match" post), and the revival of Wayne McFee's PTO-tuned TinEar Receiver.

I have most of the parts (including crystals) on hand but the financial killer will be the four-position switch. So I propose to cut this down to two crystals because the DPDT switches abound and the sockets made from the pin header strips that can be cut off as desired.

Anyway, that said, I will need to come up to speed in a PCB circuit design software that will generate Gerber files so the boards can be duplicated. After that, it becomes a matter of "packaging" the kit and for that, I will probably use the same concept I did when I mounted my K7QO crystal checker circuit:

It is merely a sample wood flooring chip I obtained from Home Depot which are variously free or ransomed off at a quarter of a dollar per chip. These can have the ugly tangs sawn away and they make perfectly marvelous bases for a project. Add the copper clad front and ground plane and you are retired in Florida, Wyatt!

Project Postscript Notes
I will do this project because I'd like to learn PCB fabrication and the related software. However, this effort was lost in the fog insofar as the local repeater association members are concerned. They seem content to bide their time on VHF and prattle back an forth -- which is O.K., I guess. I mean, to each his (or her) own. So this will herald a serious disinvestment of my time and effort with those who do not wish to learn. As someone once said, don't try to teach a pig to sing because it's a waste of your time and in annoys the pig.

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