Tag Archives: radio repair

Volunteerism

July? Has it really been that long?

Wow, yes it has in fact been that long.

20151104_161606From a building stand point… nothing new has been going on. I am still working on the Beach 40 and the Bitx 20. The Beach 40 still needs the audio section rebuilt and the Bitx20 needs some troubleshooting . I don’t have the facilities to put up a 20 or 40 meter antenna and since both radios are QRP(p), a good antenna is vital to making any contacts.

20151121_072647From an operators perspective… ya, nothing going on there ether. I need to pull down my Frankenstein/Hill Billy mast because we are having our building painted soon. I have plans for a simpler replacement that should work out fine. I’ll post about that if and or when that happens.

From an experimenters view point…  I have been kind of busy lately. Many of the newer radio projects I have been looking at use micro-controllers and embedded Linux systems. All of which I am totally fine with. There are so many other applications besides radio that I can employ these technologies. The only impediment is getting some play time in with these technologies and getting familiar with there capabilities, use, and programming.

arduinoEarlier this year I picked up some Arduino hardware. I haven’t had much time to work with it yet as the Day Job has been keeping me hopping as well as a lot of stuff in the personal life, nothing bad, just a lot of changes and preparations.

Many projects are done with the Arduino and various shields. Some require a little more direction in the form of an embedded system with a true OS. Enter Raspberry Pi and Raspbian.

rpi3bLast week I added a RPi 3B to the hardware pile and began working with it. Along with the Pi I picked up a copy of Exploring Raspberry Pi: Interfacing to the real world with embedded Linux From Wiley written by Derek Molloy.

Linux doesn’t worry me at all. Many moons ago I was a Solaris 7/8 admin as well as a RedHat 7 admin. The problem is that well over a decade has gone by since I actively worked on those systems. I have been in a Windows only environment for so long my Unix brain has turned to mush. So now I’m re-learning the Unix command line and re-acquainting myself with the Linux directory structure along with some all new unique elements of embedded systems and the Raspbian OS in particular.

With all of the projects piling up and now adding a lot of general computer stuff to the pile, Arduino Sketches, Python, C/C++, and picking up where I left off with Perl, it almost feels like I should go back to school and get credit for all of this work. I could pick up a CS degree with everything on my “tech to learn” plate right now. Add in all of the projects and an engineering degree (EE or ME) isn’t far behind. Thoughts for another time.

Radio specific plans are to read and build along with Crystal Sets to Sideband by Frank W. Harris W0IYE, and then get back to Experimental Methods in RF Design and do the same. I don’t expect to do a lot of operating other than 2 meter until we have the facilities to put up a real antenna, and there is no solid timeline for that.

Life outside radio has taken all of my time lately and I am just now slowly getting back to things. Most of it is general electronics/computer experimentation and adding to the knowledge pool right now.

So in conclusion, no I haven’t been busy, I’ve been too busy.

:-/

hamverseryP.S. Today’s post is brought to you by Hamversary. On this day in 2013 I received my license grant about a week after I walked into the Saratoga Fire Station a non-ham. Since then I have worked my way up to Extra Class, begun teaching license preparation classes to prospective hams, and I have been a Volunteer Examiner for 42 exam sessions, most of them at the Saratoga Fire Station.

I have learned so much in so many ways in this short period of time. Thank you Amateur Radio.

73,
~Jon KK6GXG 

Lab Work, Repairs

New-To-Me Signal Generator

120 kc (kHz) to 200 mc (MHz)
120 kc (kHz) to 200 mc (MHz)

On Saturday I picked up a few things at the De Anza Electronics Flea Market. The most impressive acquisition would be the Lafayette Signal Generator for $20.

I have been needing one and I was dreading the prospect of having to build one and having a tough time without the right tools for calibrating it, so this was a great find and a steal of a value, though I didn’t know it for sure until today.

One thing I have learned about buying used electrical/electronic equipment, particularly in at a flea market, is that you have to take your time and open it up, get documentation, inspect and clean the equipment before attempting to use it, or plug it in for that matter.

20150414_075130 Sunday was opening day. I noticed right away that I would need to replace the power cord grommet as it was in two pieces. I didn’t actually get to anything else until today.

Today I inspected all of the wiring and components, looked for hot spots and anything that would indicate an over heat. Having found nothing of the sort I moved on to cleaning, which there was surprisingly little to do. I made sure the tubes were cleaned and had no fingerprints on them. Now that I have a piece of tube equipment I will need to get a tube tester. 😉

With the cleaning done it was time for the plug-in and smoke tests. No pops and and no smoke! I let everything warm up and burn in for a good twenty minutes before starting any tests.

Testing with the oscilloscope began with the AF (audio frequency) side of the generator. After the twenty minute warm up period the “approximately 400 cycles” audio tone as specified in the manual turned out to be stable at 388 cycles (Hertz). I can work with that.

“kc” is kilocycles. The term is essentially the same as the more familiar kilohertz along with “mc” megacycles being the same as megahertz. The change over in terminology occurred slowly from the mid 70s to the mid 80s. Many hams still use kc and mc. I use them interchangeably depending what I am referencing or who I’m talking with. This piece of equipment has frequency labeled on the dial as kc and mc.

20150417_152319Moving on… The generator did its first diagnostics job with a portable amplifier I have had for a very long time (the one on the right). I clipped on the amp to the audio out and it turn out the volume control on the amp is trashed from banging around in my tool bags for a couple of decades so I will need to replace the potentiometer in that this weekend.

I then moved over to the RF (radio frequency) side of the generator and clipped on the oscilloscope. The RF side is divided into 5 switchable bands. I checked each band by referencing the frequency on the dial with the frequency on the O-scope. All five bands checked out very closely to the dial. A little lead or lag here-and-there, but overall pretty close for this equipment and its age which I’m guessing is about as old as me (made in the mid/late 60s).

20150417_152206The frequency counter I purchased last year has been giving me problems. New equipment, cheap (figuratively and cost), and no manual. With the help of the new sig gen and the oscilloscope I managed to fix a couple of minor problems and figure out the modes on the counter in the process. Looks like the electronics bench is finally coming together.

Now that I can check the receivers I build I can also check the transmitters I plan on building. I can also check portions of the radios as the construction moves forward. I plan on building more of my own test equipment but it’s nice to have a reference point or two to calibrate off of.

I also did some diagnostics on the 40 meter direct conversion receiver project and updated the project page… some very interesting results, you should take a look. 🙂

A productive day I think.

73,
~Jon KK6GXG

Repairs

Boafeng Hand Mic Repair

Magic Smoke?

20150228_105506I was out picking up some components from Jameco for the 40 meter receiver I am working on. It was in the morning so I figured it would be a good time to tune in to the 9AM Talk Net.

After calling in my call-sign and waiting until net control called me up wouldn’t you know it, something went wrong. I keyed the mic but nothing happened. No Tx at all, not just not being heard, but the radio showed no sign that the PTT key was pressed, nothing. Looking back it seems obvious, but at the time I wasn’t sure what the problem was so I unplugged the mic and continued without it.

A couple of days later I opened up the mic fully prepared to do what ever needed to be done to get that puppy back in service. I set aside time, cleared the bench, gathered my tools and a multimeter, laid out a mat, took a deep breath, and opened the mic case.

Wouldn’t you know, the PTT wire broke loose from the solder joint. I spotted it as soon as I opened the case. 3 minutes and a hot iron and all is well.

One quick repair down and one satisfied customer, me.

73,

~KK6GXG