AmateurRadio.com

0.33 uF X2 capacitors which measured only 0.097, 0.1, and 0.118 uF.

Many devices now use a capacitor power supply saving the space that a mains transformer occupies. The principle is that a series capacitor from the mains supply is used to drop the voltage and reduce the current. Provided that the circuit is completely isolated from human touch, this is an economical way to provide DC power.

The image shows three such capacitors as I were measuring them. They came from three malfunctioning devices in my home: two wall-mounted thermostats for floor heating and a remote controlled mains switch.

Their power supplies were designed with a capacitor of 330 nF in series with a bridge rectifier which supplies the low voltage DC. This value is typical, it seems for 230 Vac, 50 Hz circuits that are designed for about 20 mA. The value will be higher for an equivalent 115 Vac, 60 Hz circuit.

The malfunctioning happened because the value of the capacitor in my cases was reduced to 1/3 and less of the nominal value. These capacitors are all marked X2 and a voltage of 275 Vac.

The X2 means that they are safety capacitors which will not fail by short-circuiting as this would be a fire hazard in this circuit. They have self-healing properties and that means that they fail by “burning away” on their own foil, leading to a reduction in capacitance and eventually failure of the circuit as the power supply cannot supply the required current any more. They should never be replaced by anything but X2 capacitors with the same or higher voltage rating.

Go to the Wikipedia page Capacitive power supply for more description of this circuit.

By the way, the devices which these capacitor came from were 15 year old Microtemp MTN-1991 thermostats and a 20 years old Nobø System 500 RCE512 remote receiver.

Sverre Holm, LA3ZA, is a regular contributor to AmateurRadio.com and writes from Norway. Contact him at [email protected].

Last evening's QRP Fox hunt was of the 80 Meter flavor. Our esteemed Foxes were Brian K0DTJ in California and Dave N1IX in New Hampshire. "Conventional Wisdom" told me that I'd probably have a good shot at working Dave in NH, but probably not so much for Brian in CA.

This time, Conventional Wisdom did not disappoint.

I worked Dave pretty quickly. According to my log, I nabbed him at 0203 UTC. And as I suspected, Brian was nowhere to be heard. Actually, Brian and his pack of Hounds were nowhere to be heard, except for an occasional "Woof" and "Arf" from a Hound here and there.

I ended up spending the evening listening to Dave handle his pileup. It was a treat as N1IX is an accomplished Amateur Radio Op, to say the least. He handled all calls rapidly and without error. He also QRS'ed (slowed his code speed for those of you not familiar with the Q Code) from time to time when it was warranted. Dave is a member of the A-1 Operators Club, which is no surprise, and his inclusion is well deserved.

Towards the end of the hunt, Dave had fewer and fewer Hounds baying at him, and as a result, he was calling "CQ FOX" quite a lot.  QUITE a lot.  And, at the same time, his signal strength to me was actually increasing.

So at 0311 UTC, I decided to do something that I've never done before.  I dialed the KX3's power output down to the flea power neighborhood - 100 milliWatts (that's 1/10th of 1 Watt for those of you, who like me, sometimes scratch your head when it comes to scientific notation), and gave Dave another call.  In the past, I've only called a Fox a second time if I wasn't positive about being in the log, and I've certainly have never done it QRPp.

Thanks to Dave's excellent ears and superb station, I made it into "Official" log at 0311 at 100 milliWatts of power. According to QRZ, Dave lives 233 miles from me as the proverbial crow flies. So that means the QSO was accomplished last night as a rate of  2330 Miles per Watt.

Not too shabby, and you just GOTTA love this QRP stuff!

72 de Larry W2LJ
QRP - When you care to send the very least!
Larry Makoski, W2LJ, is a regular contributor to AmateurRadio.com and writes from New Jersey, USA. Contact him at [email protected].

Last evening's QRP Fox hunt was of the 80 Meter flavor. Our esteemed Foxes were Brian K0DTJ in California and Dave N1IX in New Hampshire. "Conventional Wisdom" told me that I'd probably have a good shot at working Dave in NH, but probably not so much for Brian in CA.

This time, Conventional Wisdom did not disappoint.

I worked Dave pretty quickly. According to my log, I nabbed him at 0203 UTC. And as I suspected, Brian was nowhere to be heard. Actually, Brian and his pack of Hounds were nowhere to be heard, except for an occasional "Woof" and "Arf" from a Hound here and there.

I ended up spending the evening listening to Dave handle his pileup. It was a treat as N1IX is an accomplished Amateur Radio Op, to say the least. He handled all calls rapidly and without error. He also QRS'ed (slowed his code speed for those of you not familiar with the Q Code) from time to time when it was warranted. Dave is a member of the A-1 Operators Club, which is no surprise, and his inclusion is well deserved.

Towards the end of the hunt, Dave had fewer and fewer Hounds baying at him, and as a result, he was calling "CQ FOX" quite a lot.  QUITE a lot.  And, at the same time, his signal strength to me was actually increasing.

So at 0311 UTC, I decided to do something that I've never done before.  I dialed the KX3's power output down to the flea power neighborhood - 100 milliWatts (that's 1/10th of 1 Watt for those of you, who like me, sometimes scratch your head when it comes to scientific notation), and gave Dave another call.  In the past, I've only called a Fox a second time if I wasn't positive about being in the log, and I've certainly have never done it QRPp.

Thanks to Dave's excellent ears and superb station, I made it into "Official" log at 0311 at 100 milliWatts of power. According to QRZ, Dave lives 233 miles from me as the proverbial crow flies. So that means the QSO was accomplished last night as a rate of  2330 Miles per Watt.

Not too shabby, and you just GOTTA love this QRP stuff!

72 de Larry W2LJ
QRP - When you care to send the very least!
Larry Makoski, W2LJ, is a regular contributor to AmateurRadio.com and writes from New Jersey, USA. Contact him at [email protected].

I suspect there are probably a lot of Canadian amateurs still thinking that our new 630m is not very practical for anything other than local two-way contacts.



During the winter 'DX season', this is definitely not the case, as 630m shares many, if not all, of the propagation characteristics found in the lower end of our AM broadcast band. As well, a quick tune through the even lower NDB band on a normal night will reveal dozens of 25-watters, often from over a thousand miles away and with very robust signals.

With no 630m amateur activity yet coming from VE6, VE5 or VE4, it is difficult to get a sense of just how interesting the band could become on these normal nights, or how great it would be on a really good night of propagation. My recent CW contact with the nearest out of province station, VE3OT (Mitch), on a normal night, demonstrates that there is a lot of potential for some really effective two-way work over long distances.

So ... what do signals sound like between here and Ontario? Here is Mitch's CW beacon as heard here on the evening of February 11th, at around 2300 hours local time, using my 10' x 20' loop. I have heard Mitch at even higher levels than this, but his beacon is usually audible here on most undisturbed nights, sometimes as early as 2000 hours local time. His beacon signal runs 200 watts to a 340' circumference loop, from his London, Ontario, suburban backyard.


Even if you are not able to hear Mitch's signal audibly, it should be fairly easy to copy in one of the QRSS CW modes, such as QRSS3 or QRSS10 ... both of which could yield a reasonably quick two-way contact.

Judging from the reliability of the VE3 signal, any activity from the prairie provinces should be even easier to hear. Should any of you in the prairies take up the 630m challenge, I can assure you that you'll be very, very popular out west ... every night!

This blog also provides an opportunity for my initial use of the 'tunestotube' web site. It provides a nice online interface for posting audio files to Youtube, along with an image, or a slideshow. It seemed to work seamlessly and will save me having to link to audio files stored on my own web site, which really eat up what little space I have left.
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

You can't always get what you want, but you try sometimes...

Key lineup... Palm Single (paddle), Vibroplex Bug (circa 1970s), Kent Hand key

It only seems pointless until you try

1 mighty watt

My assumptions are often incorrect

http://www.hamqsl.com/solar.html

Video

Richard Carpenter, AA4OO, is a regular contributor to AmateurRadio.com and writes from North Carolina, USA. Contact him at [email protected].

Speed does = distance over time. In terms of CW my speed is currently around 12wpm with a character speed of around 20wpm. I have been at a distance from a qso for over a month now and I am experiencing what is called a plateau. Or is this my natural speed?

If I go for a run, I know I can run at a certain pace for a certain distance. Nowadays no amount of training will get me down to what I could once do when I was in my teens (back then I could do around 1 to 2 minutes quicker for a mile). This was the same back then. I have a capacity and I know it well. Is the same true for CW?

Can I only do a certain speed?

How do I find a natural speed and maintain it? (Overtraining is a crime!)

My normal excuse is I need a new pair of trainers. Surely I need a new morse key, right?

Alex Hill, G7KSE, is a regular contributor to AmateurRadio.com and writes from Cumbria, UK. Contact him at [email protected].

A few days ago, I went out to the car as I usually do, for some lunchtime QRP.  In my haste to get everything put away after I was done, I inadvertently knocked the external battery off the car seat onto the floor. The KX3 started to move, as it was still attached, but a quick hand stopped it, and all was well. Or so I thought.


Yesterday, I went out again, and this time the KX3 wouldn't turn on. No problem, I thought to myself, the battery was probably on its way out, as it has been a while since I have given it its last drink.  So last evening, while I was attending a CERT class on animal handling during declared emergencies, I had the battery plugged in at home, charging.

When I got home, around 10:00 PM, I tried reconnecting the battery to the KX3 to see if everything was OK.  Still no sign of life - my KX3 was still flat lining..  Hmmmmmm ........ could the battery have gone totally bad?

I carried the radio down to the shack 13.8V power supply.  Viola!  It turned on! 

And then immediately turned off.


My brain went into over drive. What the %(#@*#$ was going on ?!?

I dread sending stuff out for repair.  Don't know why, I just do.  I was in the professional photographic electronics repair biz for over 20 years. I have fixed studio strobes costing well over $12,000.00.  I have taken apart digital camera backs that cost more than a Mercedes Benz. I have stared down banks of charged capacitors storing up enough electrons to supply 6,400 Joules of energy in one pop - certainly I should be able to figure out a relatively minor KX3 repair? Right?

I rolled up my sleeves and got down to it.  Obviously, this was a power problem.  But why was the rig shutting down so quickly?  Internal short?  Bad connection somewhere? Then I noticed that if I wiggled the power plug a certain way, the radio would stay on.  My mind immediately flashed back to the battery falling incident from the other day.  I must have done something to the power socket.


The advantage of building the KX3 (if that's what you want to call it) is that you know how it goes together, so you're not frightened at the prospect of taking it apart.  You've seen it in all its naked glory and you lovingly put it together at least once, right?  So what's the big deal in taking it apart?

Well, when you built it roughly five years ago, some of the finer details of how it went together get muddled up in the old memory banks.  That's why it's good to never toss the build manual!  Within about 5 -7 minutes I had it apart and had the display circuit in my hand.  A little extra light and a lot of extra magnification from a magnifying glass confirmed my suspicion.

The power socket is a surface mount device, just about like everything else on that display/control circuit board. The weight of the battery tugged the socket enough to unmoor it from its assigned, tinned pads.  When I would wiggle the connector "down" towards the circuit board, everything worked.  As soon as I let downward pressure go, the connector would break contact from the circuit board again and the radio would appear dead.

I ran upstairs for a pair of scrubs and to wash my hands to prep for surgery. NO! Just kidding!


I changed my soldering station tip to the skinniest one that I have for when I work on SMD devices and I re-soldered that connector onto its pads. I took great care to add just a little "extra" solder just to make sure the connection is good, solid and won't come apart so easily in the future.

I hastily (I'll get back to that in a minute) put everything together and fired the radio up. Fixed! Problem solved! High fives and happy dances all around!

I will have to go back sometime over the weekend to remove the front plexiglass display window, though.  In my haste, I wasn't so careful about finger prints.  I'll have to go back and clean that up.  Yes, I know ...... call me anal.  I can't help it!

But as this blog post says - the patient (and more importantly, the doctor) are doing just fine! And even more importantly - no return trip to Aptos!

PROGNOSIS: Excellent!  Today's lunchtime QRP session netted the following:

N0TA - SOTA peak W0C/PR-082 (Squaw Mountain) in CO on 20 Meters.
VP5/AC0W - Turks and Caicos Islands on 20 Meters
CT9/OM3RM - Madeira Island on 20 Meters.
PJ2/NF9V - Curacao on 15 Meters.

I chased KH7Y in Hawaii who was absolutely booming into NJ on 15 Meters, but could not make myself heard. Just goes to show, you can't win them all!

72 de Larry W2LJ
QRP - When you care to send the very least!
Larry Makoski, W2LJ, is a regular contributor to AmateurRadio.com and writes from New Jersey, USA. Contact him at [email protected].