QRSSuccess!

There it is. That's the rig we've been talking about. The astable multi-vibrator sits in the upper right. The Colpitts oscillator takes up most of the rest of the 9 square inch board. You can see the LED for the FSK circuit in the lower right. (I went with blue -- Jim, Al7RV, sent me that part.) (See that space on the lower left? I'm thinking that I could put in an SBL mixer and one stage of audio amplification to give this thing receive capability.)

After a bit of frustration during the building of the multi-vibrator, the initial on-the-air testing of this rig went amazingly well. I got home from work yesterday and finished wiring up the LED and a 5 pF cap for the FSK circuit. My frequency counter showed a nice 5 hz shift. Perfect. And the LED does flash a bit of blue light!

The sun was going down at this point, and I knew that 30 meters would soon be closed. But a quick check showed that the Belgian Grabber of Johan, ON5EX, was still picking up my QRO (20mW) rig. So I figured that this new rig (with around 10 mW) had a good chance of being received in Belgium. It took me a few minutes to spot it, but then I saw it. It was beautiful. Kind of a square wave with skirts, if you know what I mean. About 4 cycles per minute, and right on the freq shown by my counter. Here is a screen shot of the initial reception:

Nice, don't you think? One transistor, modulated by two others, making the trip over the Alps from Rome to Belgium. Here is a larger view of Johan's grabber screen. Time is marked along the bottom.
This rig will be on the air today. You can see Johan's grabber in the right hand column of this blog. Or here: http://www.on5ex.be/grabber/grabber.html
When the sun is up over Europe you probably should be able to see my signal.

Amazing: On the receive portion of this system we have billions of transistors (certainly millions in Johan's computer, and countless millions more in the internet). But on the transmit side we have only three.

Good Vibrations!

Somehow this goofy circuit diagram (sent to me by Mike, KC7IT) seems appropriate this morning. That is because, gentlemen, this diagram represents the kind of homebrewer I've been this week. After far too much struggle, and with the kind assistance of wizards from around the globe, I succeeded this morning in making an astable multi-vibrator do its thing. Not exactly a momentous achievement, I know. What you may ask, was the problem? Simple: Hans Summer's diagram called for 680K resistors from the power supply to base. But I somehow managed to put in two 68K resistors. This apparently results in an entirely different RC time constant!

Anyway, it is now percolating along nicely. The 2N2222s work fine, as do the two 10 uF electrolytics in parallel. It seems to produce a frequency of around one cycle every 15 seconds. That should be just about right for the QRSS FSK.

Thanks to all for the help and assistance provided. And thanks to xkcd for the cartoon!

Bad Vibes (No Vibes) :-(

Thanks for all the advice. I especially liked the LTSpice model -- it was good to get back to that great program. I plugged in the values that I am using (from Hans' circuit) and the 2N2222 transistors -- Spice says it should work. But no joy in the real world. I tried it with .1 uF caps -- nothing. I tried it with two fairly big 15 uF electolytics (as always, with the positive terminals to the collectors). No luck. Both collectors are just sitting there at .015 volts, both of the bases are at .6 volts. Sounds like both transistors are constantly at saturation, right?
Any other ideas? (I know I could do this with an IC, but I want to try to make it work with the simple two transistor circuit.)

Astable Multi-NON-Vibrator (Help!)

Having made good progress on my Ugly, Discrete Component, DC recever for 30 meters, this week I turned my attention to the little QRSS transmitter that I mentioned last week. The idea is to run this thing out at the country house. The inspiration here comes from Hans Summer's ultra-simple QRSS transmitter:

I ran into trouble this morning. The oscillator is running fine. But the little two transistor astable multivibator that is there to put some FSK on the signal is not vibrating. What am I doing wrong here? Instead of the BC-107s or 108s used by Hans, I'm using 2N2222s. Hans used 22uF caps. I didn't have any, so I just put two 10uF electrolytic caps in parallel. But nothing happens. It just sits there. Any ideas? Hans was running his rig off bleach batteries and was struggling to keep current low -- I don't have this constraint, so maybe by using lower value resistors to the collectors and bases?

Help me! Help me!

(I apologize in advance if this posting results in ads for other kinds of vibrators!)

Space Shuttle Over U.S. on Approach to Landing

This is an early Monday morning event. Lots of SolderSmoke fans within visual range of this flight path. (Somebody please alert Jerry, NR5A!) Spaceweather.com reports:

"Landing is scheduled for 8:48 am EDT, and it takes the shuttle about 35 minutes to traverse the path shown above. Observers in the northwestern USA will see the shuttle shortly after 5 am PDT blazing like a meteoritic fireball through the dawn sky. As Discovery makes its way east, it will enter daylight and fade into the bright blue background. If you can't see the shuttle, however, you might be able to hear it. The shuttle produces a sonic double-boom that reaches the ground about a minute and a half after passing overhead."

Please let us know if you see or hear it.

Colin's Power Meter

Hi Bill,

Thought you would be interested in the attached pics, one shows a power meter that a colleague made for me. I had mentioned to my colleague about the W7ZOI power meter after listening to SolderSmoke at work. A couple of days later I was presented with a power meter constructed from scrap parts! We work for a company that repairs cell 'phone base station equipment and the power meter was made from some scrap VSWR monitor circuits. My favourite part of the device is the heatsink fins on the 30dB attenuator along the top, which can be taken out of circuit by removing the SMA link. To use the meter, the 8V regulator is powered up and if any RF is present at the RF in, a voltage, which can be read by an external Volt meter, is output via the multiway connector. I use a ribbon cable, which has three connections used, DC (+&-) and meter test point. A graph plotting RF in against Volts out can then be used to determine measured RF.

The second pic shows a QSL card for a 17m CW contact I received for my contact with Ronny SM4RRF. I was using a low dipole and 500mW from an FT817! This was my 2nd ever CW contact.

73 and keep up the good work at SolderSmoke.

Colin M0CGH

Moonbounce Day!

Rafael in Mexico sent me some very interesting info about World Moonbounce Day. Today!

From: "MM"
Sent: Wednesday, April 07, 2010 3:06 PM
Subject: [amsat-bb] Arecibo on 432 MHz Moon Bounce

> Hi all:
> Here is a EME event you cant miss.
> Dust off your CW key, its time for Satellite, QRP EME.
>
> The 1,000 foot dish has 60 dBi on 432 mc and 400 watts.
> That comes out to be approximately 243,902,443 Million Watts ERP.
>
> enjoy
>
> wf1f
> www.marexgm.org
>
> (thanks to KB1MGI for passing on this data)
>
>
> Arecibo on 432 MHz Moon Bounce
>
> The Arecibo Observatory Amateur Radio Club will be putting the
> 1000-foot radio telescope on the air for 432 MHz EME from April 16-18.
>
> It can be heard with a small hand-held yagi pointed at the moon
>
> The scheduled times of operation are:
>
> April 16: 1645 - 1930 UTC
>
> April 17: 1740 - 2020 UTC
>
> April 18: 1840 - 2125 UTC
>
> Callsign: KP4AO
>
> Tx Frequency: 432.045 MHz
>
> Rx Frequency: 432.050 to 432.060+
>
> Tx power: 400 W
>
> Antenna gain: 60 dBi
>
> System noise temp: 120 K (cold sky)
>
> System noise temp: 330 K (when pointed at moon)
>
> KP4AO can be heard with a small hand-held yagi pointed at the moon and a
> good receiver. A 15 dBi antenna and 100 W will be enough to work us on
> CW.
>
> Operators at KP4AO will do their best to work as many stations as
> possible. Each session will start with a brief announcement and CQ in
> SSB. SSB QSOs may continue for 30 minutes to an hour, if the QSO rate
> remains high.
>
> The mode will be shifted to CW as soon as it is judged that higher QSO
> rates would result.
>
> We will listen for calls at frequencies 5-15 kHz higher than our own,
> and even higher if QRM warrants. Callers who s-p-r-e-a-d o-u-t are more
> likely to be copied.
>
> If you've already worked us in any mode, please do not call again --
> give others a chance.
>
> If we call "CQ QRP", we will listen for stations running 100 W or less
> to a single yagi. Please do not answer such a CQ if you are running more
> power or have a larger antenna.
>
> On April 18, if we reach a condition where most calling stations have
> been worked, and we judge that operating in the digital mode JT65B would
> produce a higher QSO rate, we will switch to JT65B.
>
> Note that any of these planned operating strategies may be changed as
> circumstances dictate.
>
> We are extremely fortunate to have been granted access to the world's
> largest radio telescope for this amateur radio good-will event. We look
> forward to working as many stations as possible in the alloted time!
>
> >From QRZ.COM

Homebrew Hero: Ed Roberts (RIP)

The Maker blog has a really great 20 minute podcast interview with Forrest Mims. He talks about his recently deceased friend Ed Roberts, founder of MITS and creator of the Altair 8800. The interview is really great. You guys will like it. Look for the little audio bar just underneath the article on this page:
http://blog.makezine.com/archive/2010/04/remembering_ed_roberts_the_father_o.html

Receiver Success! Combining Computers and Homebrew Radio

Well, it turns out that yesterday was a GREAT day for a new receiver. When I got home from work 30 meters was open. I fired up the new receiver and the FLDIGI program. Immediately I started to see and decode PSK-31 signals. I quickly switched over to the WSPR program and right away I could see the little two minute WSPR sigs. Here is what my screen looked like:

The program also began to automatically upload reports to WSPR HQ. Here is the report I found on the WSPR web site this morning:

I know all this WSPR and digi stuff often seems to be very computer-centric, and very "appliance radio," but I think this little project shows how we can have the best of both worlds: This rig combines a laptop computer and some pretty sophisticated software with a VERY simple, discrete component, homebrew direct-conversion receiver.

OK. So you see that I left a lot of space on the PC board. That's where the DSB transmitter (for WSPR and possibly PSK-31) will go.

BTW: You can keep an eye on my reception reports by going to the Database section of the WSPRnet site and plugging my call (I0/N2CQR) into the "reporting station" block. I'll leave the receiver on today.

A Bad Day for a New Receiver

Here is the latest picture of my version of the W3PM WSPR receiver. You can see the Ugly Weekender AF amp in the upper left. No front end of any kind yet -- the sig goes right from the antenna jack into the RF pin on the SBL-3 diode ring mixer.
Turns out that this morning was a bad time to test a new receiver. Spaceweather.com reports that a big coronal mass ejection hit earth today, causing havoc in the ionosphere. I'll try it again later today.

G0UPL's Ingenious QRSS Circuit

Just look at that circuit! That's a complete QRSS beacon transmitter, including a multivibrator (the two transistors on the left) to generate a recognizable pattern on the grabber screens. This diagram appears in SPRAT 134. Hans Summers ran this rig with just a couple of volts from his homebrew bleach-based battery system back in 2008. I plan on putting a version of this rig into the solar powered lawn lamp I showed you two posts ago (scroll down).

In other news, I finished building the Ugly Weekender AF amp this morning, and it passed the smoke test. My WSPR system went toes up this morning, so today I am QRSSing on 30 meters. I'm running my usual upside down FSK. Please let me know if you see me.

Colpitts Mania! Two Rigs Under Construction

I'm really into Colpitts oscillators lately. I blame Gene, W3PM. He reminded me of the fact that these little one transistor stages can pump out the 7 dbm needed to drive a diode ring mixer. Gene sent me a note warning that I'd have to take special precautions to ensure stability, but I found that this circuit never strayed more than 20 hertz in the course of a full day of oscillating.

Above you can see my version of the Colpitts circuit that Gene has in his very nice WSPR transceiver. You can see the SBL-3 diode ring mixer above the oscillator in this picture. I still haven't decided on the audio amplifiers.

I'm working on a second Colpitts circuit. This one is for a QRSS transmitter, also for 30 meters. Here I took my inspiration from Michael, AA1TJ, who has been working DX with power levels similar to that of this little oscillator. Long-time blog fans might recognize this board, or at least the device that it was used in. This is the board from my "DaVinci Code" 30 meter frequency standard, so called because I used a paperback copy of the Dan Brown novel as insulation for this weird piece of test gear. With my Kempton Park Frequency counter working, I had no need for the DaVinci device. But the oscillator was a Colpitts, capable of pumping out 10 mW all by itself... I plan on building a Hans Summers-style multivibrator circuit to put a distinctive pattern on my QRSS sig. It should fit nicely on the same board. I have a case and a power source in mind: see below. See if you can figure out where I'm going with this.