Are Diode Ring Mixers Fundamentally Different?

Joop, PE1CQP, and I have been discussing mixer circuits, especially the ever-popular diode ring.
Here is my latest e-mail to Joop. The RSGB diagram for the ring diode mixer appears above.

Joop: I think the way the diode ring mixer works is very different from the way a two diode singly balanced mixer functions. The effect, of course, is the same. But the polarity reversing element introduced by the ring configuration -- it seems to me -- makes this a very different circuit.

Attached is the RSGB Handbook diagram I mentioned. I like it, because you can really SEE how the actions of the diode ring produce the sum and difference freqs (you have to keep Fourier in mind, and imagine the results of filtering).

The two diode circuit simply "chops" the input signal at the rate of the LO. And it would even work in a non-switching mode -- you could, for example, use FETs instead of the diodes and bias them to operate in the non-linear portion of their curves, right? This makes me think that the diode ring mixer circuits (aka "polarity switching mixers" or "commutating mixers") are very different.

73 Bill

Balloon! Project Blue Horizon Reaches Mid-Atlantic

Wow, that's an exciting track. The intrepid radio amateurs at Cornell University have a balloon up over the mid-Atlantic. It is approaching my old stomping grounds in the Azores. Beacons are onboard and reports are requested. Here are some more details:

Balloon Launch - Assist in Tracking

The NS3 group of Cornell University engineering graduate students will launch PBH-9 (Project Blue Horizon) from Lockheed Martin in Owego NY on Sunday evening, 19 Apr 09, at approximately 21:00 EDT (Monday, 20 Apr 09, 01:00UT)

This ARHAB flight (Amateur Radio High Altitude Ballooning) will ascend and then float for up to 50-hours while drifting to the east.

The payload will include a KC2TUA-8 144.390 APRS beacon
(track via (http://findu.com/cgi-bin/find.cgi?call=KC2TUA-8)
and HF CW position report and telemetry downlinks on 7.104MHz and 10.148MHz.

The NS3 PBH-9 team requests distant ground stations receive and report HF telemetry via N2XE@arrl.net including reception UT date and time.

Distant receiving stations are welcome to also submit HF
reception reports to W0RPK@amsat.org for the ARHAB <50mhz href="http://showcase.netins.net/web/wallio/ARHABrecords.htm" target="_blank">http://showcase.netins.net/web/wallio/ARHABrecords.htm.

Additional PBH-9 information including HF telemetry transmit schedule and format is available via
http://showcase.netins.net/web/wallio/ARHABlaunchannouncements.htm.

Flight updates are available from the NS3 PBH-9 team
via http://twitter.com/pbh3.

WSPR Double Sideband Success!

Oh, how sweet it is. Today I finally got my WSPR station working. Before departing for Sicily, I installed a diode ring mixer (supplied by Jim, AL7RV) between my MEPT oscillator and my two stage 50 mw power amplifier. I thought I might have enough audio coming out of my sound card to modulate the transmitter, but I soon found out that I needed more AF. Lazy after a week on the road in sunny and snowy Sicily, I reached into the junkbox and pulled out the guts of an old computer speaker amplifier. Some really ugly jerry-rigging ensued. The amp is now sitting near the TX, powered by its own 9V battery. Looks like I'm getting about 25 mw out, but that's from both sidebands. So I'm guessing I'm at around 10 mw.

Following guidance from Gene, W3PM (whose FB SSB rig inspired this effort), I set my oscillator at 10138700. That puts the upper sideband in the middle of the WSPR band.

Here's my first set of reports:

								Reported		Distance
Date	Call		SNR					by		km	mi
2009-04-19 18:32	N2CQR		-18					DL0TUH		1353	841
2009-04-19 18:32	N2CQR		-24					PA1GSJ		1343	835
2009-04-19 18:30	N2CQR		-19					DL0TUH		1353	841
2009-04-19 18:26	N2CQR		-22					DL0ODX		977	607
2009-04-19 18:26	N2CQR		-30					G8BKE		1519	944
2009-04-19 18:26	N2CQR		-26					PA1GSJ		1343	835
2009-04-19 18:24	N2CQR		-23					PA1GSJ		1343	835
2009-04-19 14:24	N2CQR		-22					M0WQR		1601	995

Hey, is this a first? Has anyone else run WSPR DSB?

Sicily, Mt. Etna... and The Godfather

Here's some Italy travelogue, well, actually Sicily travelogue. Above, our two heroes are seen with the Etna volcano in the background. Etna is Europe's largest active volcano. It was spitting out lava while we were there. The top is currently at about 10,800 feet (3300 meters). (It varies!) We went up to the 8200 feet (2480 meters) level (via cable car). Here is what it looked like from there:
It was COLD up there. We didn't stay long. Within 90 minutes of this picture being taken, the kids were back at sea level, and in the pool at 80F.

Here is a GoogleEarth View. The yellow marker shows the place at which we took the picture of us in the snow. (The Google shots were from May/June 2006).


Those of you who are fans of The Godfather movie will remember this scene:
Well, here we are, in the same place (but without the shotguns):

Francis Ford Coppola filmed most of the Sicilian scenes not in Western Sicily (where the village of Corleone really is) but in the East, near the beach resort of Taormina, in the village of Savoca. The Bar Vitelli is where Michael Corleone met Apollonia's father. Savoca also has the church where Michael and Apollonia began their brief and unfortunately explosive marriage.

We really liked Sicily. It is a beautiful place, rich in history, and with really nice people.

In Sicily

No posts to blog this week -- we are in Sicily, near the Etna volcano.
Beautiful place. Will talk about this in next podcast. 73

SolderSmoke Podcast #105

On #105: 

http://www.soldersmoke.com

Italy Earthquake
WSPR DSB, WSPR MP3
SBL-1 Blues
Clockwork minimalism
QST articles (design, HBR RX)
Marconi
Spring SPRAT
Blog stuff
ECHO-QSO with Mike, WA6ARA
MAILBAG

Happy Easter! 

Parachutes and QRSS

Kevin, AA7YQ, has made innovative use of a parachute. You are right Kevin, this must be a first:

Howdy Bill, It’s Kevin here in Montana, the ex-Smokejumper. I’ve been meaning to write again. Thanks for the nice comment on SS #100 I got a kick out of it. Anyhow, just thought I’d drop you a note to let you know I finally had a weekend to design and build up a QRSS beacon. I used a Cypress PSoC CY24123A uC to function as the Crystal Oscillator, and keyer. The final is two paralleled BS-170 MOSFETs running in Class-E mode to give me about 560mW out with a 7.5volt Lantern battery as my supply, total system power efficiency is about 63%(RFout over DC in), I’m sure this could be significantly improved, but good enough for now. After several hours of tweaking the capacitor values I finally got the oscillator to fall into the 100Hz window. That was MUCH harder than I had anticipated. With the original version I switched the PA on and off for true QRSS 3 CW, but found this made a significant frequency drift problem. So I added a couple parts and modified the PSoC code a bit, now its running CWFSK, switching about 1.1pF on and off one leg of the XTAL, shifting the frequency about 10Hz and much more stable.

My first tests were with the board sitting on the bench under the desk lamp. This caused all kinds of drift problems. I then put the beacon in a Tupperware container and placed it inside a soft case cooler. I was looking around the shack for a blanket or something to further improve the insulation, when low and behold sitting in a garbage sack… was a condemned FS-14 parachute (equivalent to the SF-10A) that I was planning using for something useful. So I wrapped the chute around the cooler and stuffed it all back in the garbage sack. Surprisingly, temperature stabilization was achieved, beyond my expectations.

The beacon is running good now, nice and stable. I’m fairly certain, that in the history of mankind, no one has ever used a parachute to improve the temperature drift characteristics of a QRSS beacon. Anyhow, I plan on having it fired up quite a bit, so that my antenna is actually put to some good use. It seems I rarely get a chance for one to one contacts anymore. Most of my free time is spent designing and building the radios I never use. Ha. I guess the design and building is the real fun for me.

Anyhow, I’ll talk to you later. 73s Kevin, AA7YQ

PS the Beacon is sending “AA7YQ” followed by a several second pause. It’s showing up on the K6HX grabber between 10.140050 and 10.140060.

2N35s, 1955... and some inspiration from AA1TJ

From Michael, AA1TJ:

Bill, I was re-reading Ade, W0RSP's "History of QRP" last night; especially that last chapter on transistor rigs. It dawned on me that the two 2N35 transistors that I'm presently using in my 40m transmitter were built two months before Bob, W7UUZ's famous, maiden transistor QRP contacts in August of 1955. While we can't go back and beat Lindbergh's first solo crossing of the Atlantic, for example, a fellow could re-live some of the excitement by building a replica of The Spirit of St. Louis and taking it up for a spin. If anything, it gives one a better appreciation of the hurdles those early trailblazers had to leap.

That's Michael's 2N35 rig pictured above. For more details see:
http://mjrainey.googlepages.com/80mqrptransmitter;circa1955

Michael also put a really great message on QRP-L earlier this week. I hope he reprints that on his blog.

SolderSmoke: On Sale on Thai Beaches!

An interesting e-mail from Thailand arrived this week. Excerpts:

Hi Bill Now for the full story

Life was so uncomplicated and peaceful before soldersmoke!

Last October I was lying on the beach in Pattaya City Thailand. I was just lying there enjoying a cold rice beer watching the various peddlers trudging along the sand. I wasn't bothering anyone and thought I was enjoying my retired life style. (Little did I know what was about to happen). Casually the wife reminded me there was a Ham club meeting in about three hours, I should hold off on another beer. Ok, I'll manage till later.

Pattaya Thailand has a great little Ham Radio club with locals from all parts of the world enjoying the one universal hobby without boundaries.

We showed up at the meeting on time and found a nice corner table. ( now the plug for the club - the meetings are the Friday after the first Sunday of every month and are held at Jimbos Bar). After about an half a beer a friend from England wandered over and sat next to me. He produced a CD from his pocket and said is was SolderSmoke, would I like to buy a copy for 100Baht. (approx. 3.00US) . As with most normal people, my first question was, what is soldersmoke? This was my first big mistake. I should have said not interested and looked for other friends that were arriving. But, no, I had to ask what was SolderSmoke.

My friend tried to explain, but feel short of being able to fully relay the meaning of the word SolderSmoke. If I remember correctly there were episodes 1 thru 80 something. I took the CD back to my house. and the next day spent over 5 hours glued to the CD player. My world was beginning to crumble.

I listened to more episodes. and started to think in terms of QRSS, QRPp, long wires etc. This new terminology was fascinating. I grew up in Idaho and was first licensed in 1963. I still have my first rigs that consisted of a Hammarlund HQ-100 and a Knight Kit T-60. I apparently had the knack at age 13 or so, but didn't know what it was called then. hi hi

In a couple of SolderSmoke episodes there was mention of a Drake 2B, a great receiver in all respects. I found myself wanting one (I sure didn't need one), and looking every where. I bought one in great condition with the original for sale tag still on it. It even had the crystal calibrator installed.

Now my vocabulary has expanded to whisperers, grabbers, mickums, reggies, knights of the realm and other terms before unknown to my vocabulary. Fessenden was a terrific individual although I'd never heard the name before episode 90 something. I started to build a QRSS beacon. I am in constant contact with Michael Rainey , AA1TJ. He is a great guy and has helped with a lot of questions.

For the first time in several years I am involved with something I enjoy. This is really fun I said to myself after fabricating a one transistor transmitter patterned after the discontinued ONER. 0-Yes let's not forget Mr. Doug Demaw, I bought the QRP notebook and Solid State Design (I didn't tell the XYL how much this book cost).

I've always been taught that addictions are bad things. I am in serious trouble now. I am thoroughly and completely addicted to SolderSmoke. I get impatient and unpredictable when the podcasts are a little late being posted on the internet. It's just like getting your fix for the week. Yes, fix for the week because it doesn't last the full two weeks. hi hi

I guess this is a non e-cursing thank you kind of Email. SolderSmoke has ruined my life, but my new life is much better with it.

Hope this epistle hasn't bored you to much. Your providing a great focal point for fellow knack victims.

Only thing left to say Bill, is KEEP ON SMOKIN!


Thanks for SolderSmoke

73 de
Stephen (Himself) (seems like everyone has a nickname)
HS0ZHB / NM7J

More Seismic Action

Two more fairly strong jolts today, both from the same region NE of here. The 4.9 was very noticeable at 11:25 am local time, and the 5.6 really shook the apartment at 19:47 local.
The USGS site is really very useful and up-to-date. Lots of data. For example, we learned that the compression wave from the 5.6 jolt took about 15 seconds to reach Rome. The people up in Abruzzo are really suffering and each one of these aftershocks makes things worse for them.

	MAG	UTC DATE-TIME y/m/d h:m:s	LAT deg	LON deg	DEPTH km	Region
MAP	5.6	2009/04/07 17:47:38	42.349	13.405	13.1	CENTRAL ITALY
MAP	4.5	2009/04/07 17:32:53	32.984	47.833	10.0	IRAN-IRAQ BORDER REGION
MAP	5.0	2009/04/07 15:18:41	37.620	-17.441	8.3	AZORES-CAPE ST. VINCENT RIDGE
MAP	4.7	2009/04/07 14:50:02	46.099	151.609	58.1	KURIL ISLANDS
MAP	2.9	2009/04/07 14:46:42	33.883	-116.872	14.4	SOUTHERN CALIFORNIA
MAP	4.5	2009/04/07 14:20:10	-7.970	122.916	236.7	FLORES SEA
MAP	5.1	2009/04/07 13:29:48	-6.976	129.425	69.7	BANDA SEA
MAP	2.9	2009/04/07 13:10:43	19.256	-65.076	63.6	VIRGIN ISLANDS REGION
MAP	2.9	2009/04/07 10:08:55	32.209	-116.626	0.0	BAJA CALIFORNIA, MEXICO
MAP	4.9	2009/04/07 09:26:31	42.336	13.360	10.0	CENTRAL ITALY