Friday, September 20, 2013

Fun with diodes...

Been playing around with crystal radios lately.  I have a loose coupled radio that consists of a pre-selector tuned circuit, a detector with a 1N34 germanium detector than can be switched out to allow external detectors to be used with the tuning circuits.  Lastly, I have a wave trap tuned circuit that can be used to null out strong adjacent signals that might otherwise swamp the desired signal.  These three modules are all built up in separate boxes and just placed near each other to couple together as strongly or weekly as desired by just varying the distance between them.

Now I am playing around with point contact semiconductors.  This one is galena though I have some iron pyrite I would like to try as well.

I have built a few "fox-hole" receivers using the old blue double edge razor blades and a pencil but never got a chance to play around with point contact rectifiers made from minerals until now.  Should be fun.

Saturday, August 24, 2013

What do you get...

...when you combine a dog bumper launcher...

...with a 22 caliber blank cartridge loaded in the handle of this rather innocuous looking device?

Well...  Tie a bit of kite string around the bumper (the white bit on the end), make some big loops on the ground with the line, insert ear plugs, stand behind and well clear of the line, pull back the spring loaded plunger on the bottom and it's bye-bye-bumper...

I used it today to launch over my house (which has a 45 degree (12/12 pitch) metal roof) a belaying line so I could get up there and clean some moss off the skylights and inspect the seals.

The bumper flew about 200' in the air before the trailing line slowed it down and dropped it in the front yard.  You will get the neighbor's attention as the sound of a gun-shot rings through the neighborhood...  I live on some acreage out of the city limits, so no boys in blue arrived on my doorstep.  Guess I will fail the GSR test at the airport security checkpoint, eh?

I am not sure I can be very accurate with this thing to carefully place antenna lifting lines, but it certainly worked a treat for my get a line over the house to anchor to the pickup truck activity.

We of course had to turn a pack of golden retrievers loose to chase an untethered bumper which was a bit of a riot on a sunny Saturday in the northwest.

Monday, August 19, 2013

Time for a new antenna

I have been getting the itch to try out a horizontal loop antenna for some time now.  At the recent Salmoncon event, Eldon - WA0UWH put up a 40 metre vertical delta loop that we fed with 450 ohm ladder line.  The results were, in a word, amazing.  The top of the delta was at about 100' with the other two sides hanging downward and joined at the centre by the feed line.  Running Eldon's FT817 at 5 watts, if we could hear it, we could work it.

Wanting to duplicate these kinds of results at home, I am keen to try out a loop, but in my location, I am only able to obtain about 50 feet of elevation.  I am also interested in top band (160 metres) so a bigger loop is in order.  This will require about 514 feet of wire which works out to about 128.5 feet on a side.

Looking at my site, I have four candidate trees for supports that will provide the ability to build a corner-fed trap trapezoid loop.  The proposed site plot looks like this:

The building is oriented the long way north/south and with this orientation of the loop, I would feed it at the lower left (southwest) corner.  Each of the legs is at least 180' long, so there would be plenty of room for a 160 metre loop.  I wish I could get it up higher, but I guess that will have to wait for trees to grow.

Monday, June 24, 2013

Checking in...

Been a long time since I have been blogging at all.  Happy to say it is because I have been very busy with the new job and getting settled into a new routine.  I was out of work for 4 months after being laid off from Microsoft and am now back working with Dynon Avionics as a Senior Software Developer.  I am having fun and working on some interesting projects that allow me to exercise both my hardware and software skills.

I have been playing around with PSoC devices from Cypress (  Specifically I am playing with PSoC 1 devices.  We are using them in a number of our products and in my new role, I found it necessary to learn about these devices and effectively take on another microcontroller.  Pretty fun and I hope to incorporate some of these devices into some of my ham radio projects in the near future.  Stay tuned...

Sunday, May 5, 2013

Blogging from Raspberry Pi

It is a beautiful sunny warm summer day in Seattle.  Been out this morning enjoying the sun and running errands.  I have fired up the Raspberry Pi and thought I would try to update the blog from the Midori web browser included in the Wheezy build.

Spent way too many hours yesterday in the print shop getting an order out last evening and today Joan is off to eastern Washington to pick up a Fjord pony so I thought I would play a bit with the Raspberry Pi.

I ordered a couple 32 gig memory cards and will be trying to get a couple of different distributions working on them.

It is good to be working again after being laid off from Microsoft back in January.  I am now working at Dynon Avionics in Woodinville doing software for their avionics product line.  Happy to be employed again!

We have had one of those fantastic weeks of sunshine here in the northwest that make it one of the best places to live.  When the sun is out in Seattle, there is nothing better.  Unfortunately, there are a whole lot of grey sky days in between.

I am currently scheduled to go pick up my airplane Tuesday after it's rather lengthy annual inspection.  However, it is looking like the weather may not hold until then.  We shall see.

Sunday, March 24, 2013

Ham Radio Presentation, Raspberry Pi and WSPR

Hello out there.  It seems that I have slowed down sufficiently on the job search to play a little this afternoon with radio related stuff.  I had an opportunity last Monday to give a talk on Ham Radio to the Community Club in Ocean Shores Washington.  Pretty high level stuff, but had a number of hams in the room as well as about 20 mostly retired folks from the Ocean Shores Community.  It was a lot of fun and seemed to be well received by the audience.

I was also asked to visit the high school and meet with a group of students and talk about aviation and software.  I met with the students in the morning and gave my talk around noon to the community club.  All-in-all a very nice day for me.

I have been busy in the screen print shop, but this afternoon decided to play around a little with the Raspberry Pi machine and get it up and running on WSPR.  It really was a non-event as the work all seems to have been done for me by others.

I booted Debian Linux off an SD card and found that I could not connect to my wireless network as the Netgear Ethernet bridge I am using had not been reconfigured to use my updated network settings.  Once I got that sorted out, the Pi booted up and internet access was now working.

I updated the Debian release to the latest stable and installed Git as well as updated my gcc release.  I then cloned the WSPR code from github and built it on the Raspberry Pi machine.  It is now up and running and transmitting on 10.140.200.  I am able to hear it on my Grundig G6 portable receiver and it seems to decode fine using Joe Taylor's fine WSPR software.

So not terribly earth-shattering news from KO7M, but it is fun to get back to doing something with ham radio again.  My buddy Eldon seems to be having trouble with this as he is complaining of AC hum issues, so I think I will take my setup with me and go pay him a visit.

Sunday, January 20, 2013

More time on my hands...

Well, it seems I will be having more time to melt solder and sort things out in my shack as I recently lost my job due to reductions in force.  Going to take some time off and decompress after 26 years, but will be looking for the next adventure.