Monday, August 24, 2015

The Hombre's Return - Handy Homebrew RF Resources, Permission to Fail & Errata

Greetings to all. Please excuse my hiatus from updating this blog. I assure you that it was not from a lack of productivity. I have been busy building, studying & experimenting with all aspects of my autodidactic pursuit of RF wisdom. I have SO many projects and builds that I am eager to share with you but there will be plenty of time to "show off" my projects in the future.

Many of my projects fail to work or meet my goals in some way. Sometimes it is an issue of poor planning, incorrect assumptions, wrong measurements or even over ambition. Many of the times it is the inability to create the circuit/system in the form factor that I envisioned.

One of my recent projects was Roy LeWallen's Optimized QRP Transceiver. I worked on this project over the course of three months. Most of that time was spent drafting the layout on graph paper. I will share this story, including photo's, design/layout tips and a humble true confession of why the project failed in the end, in a planned future blog post titled: "QRP My Problem Child". For now I am simply giving that experience as an example of a very frustrating failure to turn a homebrewed transceiver into a user friendly radio. The problem was the inability to create a proper enclosure for it. Steven, KC2SIZ, created a post on the QRZ > Homebrew forum called 'The Homebrewer's Lament' that I recommend you check it. He shares his thoughts and frustrations that I believe many of you will relate to.

The topic of failure is important. If we don't give ourselves permission to fail then we are denying ourselves the right to learn. Experimentation is all about failure! I wish to encourage everyone who is interested in building circuits of any kind, whether you have years of experience or none at all, to watch this incredible video by Jeri Ellsworth: Secret to Learning Electronics - Fail and Fail Often

In this informal post I also wanted to share a few tips for resources that I have found helpful. Whether you are recalculating the component values to change the band of a published transceiver design, designing your own circuit from the ground up or needing to do quick math on the bench to determine how much parallel capacitance you need to bandspread your VFO, a calculator is a wonderful tool. There are a number of great online calculators and free programs to help us solve design problems but sometimes it's nice to have one on hand, in pocket or on the bench.

 While in fact any dollar store calculator will work just fine, I wanted to find one that was a little more specific to my needs (I should mentioned that if it wasn't for my father offering to purchase it for me, I would most certainly have taken the route of the skint hombre & got the $1 shop calculator). I started my search by digging through posts on the EEVBlog Forum to see what the real engineers were recommending. What I discovered was dozens of pages of discource debating the merits & faults of various brands, models & systems. There seemed to be as many different types of calculators as there are branches of engineering! I started tallying up the recommendations for each particular model. I then narrowed it down to the ones that were in my price range & being sold as new online. Many of the suggested models where vintage and extremely expensive or unobtainable used. I decided on the Casio FX-991MS Plus.

The Casio FX-991MS Plus has the feature of being able to use the engineering notation for pico, micro, nano, Kilo, Mega, etc. so it makes solving circuit problems much easier than other calculators that require you to count the zero's or use other forms of notation. I highly recommend it. In a later update to this post I will cover some of the keystrokes & features of this calculator as well as give some examples of how to solve some of the equations we use when working with RF circuits. So please check back in the near future.

Thanks go out to Chris Gammell (of TheAmpHour, ContextualElectronics & and to Pops aka Todd aka VE7BPO ( for their neighborliness and encouragement for me to continue developing this blog despite the lack of visitors. Thanks guys.

That is all for now.  This was just meant to be a quick informal post but I plan on creating many more in the coming weeks so please check back for more homebrewing tips, circuits, project photos, tutorials & ramblings of an RF Hombre.

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