Friday, 13 April 2018

SNA Completed and Many other Projects to Fill the Gap.

Been a while since my last entry, but at least that’s due to being so busy at the bench.  Finished all the testing for the SNA, completed the documentation all in time for last week’s buildathon.
The buildathon went great and there were about 18 builders present with a few more to start the build this weekend. 

We had a solder oven present, and I was surprised that there were I think at least 4 or 5 completing the build by hand. The boards I saw that used the oven turned out very well.  This is the second time we have used the oven for a project and it’s proving that the oven method is indeed a good approach.  I have had some parts on hand for a while to build an oven, but never got around to it.  I think I may just bump it up on the shack to do list.  Then there is the issue of solder paste. I get that the shelf life often mentioned is likely for industry standards, but I think for use in the shack the life can be extended.  By how much who knows?  I wonder if you can freeze the stuff and thaw it out when you want to use it. 

At the moment I’m trying to figure out how to communicate to an ESP8266 module.  This endeavor is looking more and more like it’s going to get the better of me. Between trying to just simply use it or flash it, nothing is going smoothly.  This project is one of those things that you build or do and figure out a use for it later.  I thought it might have been a good exercise in clearing my mind from the sna project.  Well it’s certainly has done that.

Another project in mind is using Python to communicate to the sna command line interface. It means learning something about Python and I haven’t even got a good handle on the Arduino environment yet.  

The Chat With the Designers have a good series this year with projects involving Arduino. So I’m thinking I might pick off a project or two there. 

The sna project started several conversations around all kinds of different concepts which offer good learning opportunities. However one in particular revolved around complex impedances and how to measure them.  The AD8302 chip seems to be the answer and I do have an 8302 board on hand. So there’s another project on the list.

During the sna project the use of an rf bridge was required for some of the measurements.  I have a homebrew one on hand and I’ve never really questions its use.  When making comparisons with others in the group with the results they were getting, questions on the accuracy of the different bridges came into play.  So I ended up building 3 more versions. One of which was made as small as possible and with SMT components. I also purchased another bridge that is of a different design. So another item on the to do list is a through testing comparing these bridges.

Time for re doing my crystal test fixture. I think I’ll change components to smd and re package it so I don’t need wires going to the crystal socket and bnc connectors. Try and eliminate as much as possible any stray influences. 

Problems attributed to patch cables came to light during the sna project. I guess the sensitivity of the sna highlighted possible issues with cheap cables and connectors. Haven’t decided how I’m going to approach this as top quality cables has a price tag that I don’t want to deal with.  I had one cable in the mix that seemed to be intermittent and eventually I noticed that the centre pin in one end was the issue. So maybe my eBay cables will do fine as long as I keep an eye on the connectors.

Another project I’m contemplating is an automatic switching attenuator.  There are some interesting attenuator chips out there that seem to be right up what I’m thinking so we shall see what happens there.  Maybe I’ll find something at Dayton this year this will fit the bill.

The list never stops growing and still on the list is finishing up my Bitx.  Won’t take much to get it completed.  Far more time will take place doing all the hacks for it.

Here's a picture of the finished sna in its case:

Well time to get back to the bench and see what happens.  True to fashion is one project leads to a couple of more and the sna project certainly lived up to that statement.

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