Minima - Wayne's Build

Sunday I had a chance to work with Jeff - KO7M via Skype for a few hours. He has the loan of Wayne's (NB6M) Minima Transceiver for a few weeks while Wayne is on vacation - Thanks Wayne.

A large part of the discussion was about "How to Use Git and GitHub" for software development.

Wayne's Mimima

Afterwards, we decided to try to update Wayne's Minima to my latest Alternate Tuning Method transceiver control code. Wayne had previously downloaded and was using a much older copy of my code. The older copy did NOT have many of the NEW and current features and functions. Our goal was to exercise these new features on Wayne's hardware.

When we first downloaded my NEW Revision, Wayne's Minima went NUTS, with a loud Buzzing sound on all frequencies.

We reinstalled the old software and the Buzz went away.

Something that I had done over the last few weeks has made my software almost useless. With a little work, and via the process of elimination (removing sections of code), Jeff was able to track down the offending routine.

I had inappropriately moved two of the PTT Pin Initialization Statements to within the main TX/RX Idle Loop. This pin is also used to control the TX/RX relay. Rapid re-initialization of the PTT pin was producing hash that the receiver was picking up. Removing the two nu-necessary and redundant statements solved the problem. Initialization of the PTT pin is now done between Receive and Transmit and then when switched back.

The GitHub copy has now been updated.

While we had Wayne's Minima NOW working so well with the new updated code, I wanted to exercise each of the new functions. Wayne does not yet have a "seventh" push button installed, and therefore we had to use a jumper wire as a switch to access some of the functions. For the full list of new functions that I have added to Farhan's original Minima code, see Link. Everything worked better than expected - I am a Happy Camper.

One of my main interest was to see how well the CW ID and MACRO's worked, and how well the QRSS Beacon worked. They actually worked much better than expected!!

The Non-Volatile Save and Load of User Memories worked as expected. Dial Calibration for both USB and LSB was an easy task.

Over the next few weeks, Jeff will be introducing some new hardware support and functionality for the Minima. He has plans for multiple Si570's (VFO and BFO), other I2C Displays and more. See his blog at: http://ko7m.blogspot.com/search/label/Minima.

Contributing to the Minima Hardware and Software has been a very rewarding and interesting project, . . . Thanks, Farhan.


-- Home Page: https://WA0UWH.blogspot.com

SMD - Without Solder Mask

The last few days I have been soldering several of my Home Brew (HB) PCB's and playing with several different ideas for the best method of mounting SMD parts. My projects do not have the funds for proper solder mask.

I have tried loading the board with components on solder paste. The solder paste that I use is intended for stencil application - which I have found, if thined with a solvent, works very well when applied with a blunt round tooth pick. Parts are easy to place and stay in place. The PCB.s that I tried was very dense and because it is HB, I did not have a solder mask to help prevent parts from moving a little when re-flow in a toaster oven. On one occasion, two adjacent parts  floated to join at one end, at it turns out the two ends had a small trace between the pads, but it was enough for the solder to flow to each other. A production solder mask would have prevented this movement.

Also, I tied using a small iron with solder pasted parts, because of the density, I have several SMD 1206 parts with a trace between pads. Pressing the parts into the paste squished the paste under the part and that provides a potential short to the trace under the parts. Most of those parts had to be re-fitted. Lesson learned, be extra careful with parts placed over traces - avoid it if you can.

I have tried, and like direct soldered SMD's, which works well for me. I suggest several things;

• Just before installing parts, clean and polish the board as normal, then rub a thin layer of "Flux" over the board, it is a bit messy but it can be cleaned up later. Solder acceptance if much faster and stays cleaner while installing parts. Clean solder does NOT drag when releasing the iron from the pad - resulting in fewer bad joints or shorts.
  

• I suggest, for a new parts, 

1. Tin ONLY the first pad.
2. Place the part on the pads, one end will be setting on the solder mound from step 1.
3. Hold the part down gently with a tooth pick.
4. Heat the first pad with a small soldering iron.
5. Allow the part to drop onto the pad as the solder melts.
6. Do not try to add more solder - that will be done later and only if necessary.
7. Do NOT solder the other pad, for now.
8. Repeat for a group of  SMD parts.

• I like the idea of have a second chance to look at the newly installed parts, one last time before committing to a double ended soldered part.  
  

• Note: Once a part is soldered on both ends, and if it needs to be moved/removed/replaced - it is the same as a board repair, which is never as clean or easy as a new part installation. Removing a part with only one pin soldered is very easy.
  

• I found that small diameter 62/36/2 Rosin-Core Solder works much better than most other solders that I have used (available from Radio Shack on small spools) - the 2% silver makes for very smooth and shiny joints. Note: I have NOT found another source for this type of solder, a friend, Wayne McFee NB6M put me onto this - thanks Wayne.
  

• If necessary check adjacent traces for solder and solder paste shorts under the parts, they are much easier to find with fewer installed parts.
  

• After inspection, solder the other pad(s) of the SMD parts, then touch up the first end only if necessary - the previously rubbed on Flux make the joint touch up just that much easier.

• After soldering is complete, clean the board and remove the Flux as normal - I don't suggest Acetone - I like to use an Isopropyl Alcohol (99% , from the drug store) bath soak and blow dry, and the maybe followed by  a "Contact Cleaner" as you get some pressure-washer spray action, and it is easy to use. Rosin is an organic flux and Alcohol is an organic solvent.
  

• I use the "Carburetor Cleaner" (from the auto store) to pre clean the PCB before Toner Transfer and for Toner removal after etch - Carburetor Cleaner is Great Stuff.

So far, I have successfully produced several HB PCB's, some with very small 8 mil traces, and I am very very pleased with the results.

-

pQRP P&C Meeting

The following was reported by Wayne, after our Puget Sound QRP (pQRP) Pie and Coffee (P&C) Meeting, republished here as an archive.

Note: I did not invent the Toner Transfer Process to produce PCB's, I used a lot of information form the WEB, thanks to the many people that have gone before me.



Hello All,

We had a great turnout at P&C last evening, with fourteen of us around the table. Here's the list:

Roger, K7RXV
Jeff, KO7M
Rod, WE7X
Eldon, WA0UWH
Charlie, K7KN
Bob, W8MCJ
Rick, K7MW
Lyle, KK7P
Doug, W7RDP
Rich, AC7MA
Brendan, N0BML
Bill, WA7NCL
John, KC7NVE

Although most of us have been busy with summertime activities, there have been a few projects going on.

Eldon, WA0UWH, has worked out a method for producing PC boards, using an ink transfer method involving a laminating machine. He'll have to explain it in detail for us, but it looks very interesting.

He brought his 40 dB Tap project along for show and tell, also, having cut the PCB material to Roger's specifications and now getting ready to build it.

Eldon is making his shop available to any of us on the 3rd Saturday of each month, for radio or other types of building projects. He has everything from wood working equipment through metal working gear, including a lathe and milling machine.

Lyle has built his RF Test Set, and his lack of output from the DDS board was caused by the fact that his DDS60 is an older one with a different DDS chip and clock frequency. Rich is going to try to adjust the firmware so that Lyle will be able to use the older daughterboard.

I have been so busy with being the Commodore of my local yacht club, hosting company, and the usual summertime activities, that I have not been doing any building projects and have not been on the air, either. My time will free up a lot in late October, and the onset of the rainy and dark season will turn my interests back to the workbench and paddles.

Jeff, KO7M, brought his recently built HF Packer Amp, that he built from a kit, and it is very nicely packaged and will be a nice addition which will give his QRP RF output a good boost to help make contacts in this time of low sunspot activity.

Bob, W8MCJ, came with a box of free stuff like coax cables, some ham related books, and gave a copper ground strip with braided connecting wires to tie rigs together and to ground as a door prize. Lyle gratefully received this unit.

As usual, the discussion around the table was varied and lively, ranging from a little teasing towards Doug, W7RDP, about the recent docking mishap with the Wenatchee, the Washington State Ferry he works on, to various computer programs for MAC and Windows Vista, as well as QRP Radios and operating events.

Bill, WA7NCL, talked a bit about operating in a recent "Bumblebee" event, and made a suggestion for next Salmoncon, saying that since we tend to focus on building projects, we should have an operating event at Bowman Bay, where we each put together a portable QRP station, hike over to the point, throw an antenna over a tree, and operate for a while. Could be a lot of fun.

Rod, WE7X, brought in an award that he and Doug, W7RDP, had won in a recent VHF Contest. Roger, K7RXV, had been along on that trip as well, but didn't operate.

Brendan, N0BML, talked about his building project at Eldon's last shop gathering, which was a homebrew charger unit for his cell phone. Brendan is also practicing CW and getting ready for an upgrade to his license.

If I missed anything, it was simply because there was so much being discussed.

In short, it was another very enjoyable evening.

73,

Wayne NB6M