Happy 6L6 DAY!

Cory, WA3UVV, sent in this nice article about a beloved vacuum tube:

Say "73" to the 6L6

Sometime in the spring of this year, the 6L6 will celebrate it's 73rd birthday. Originally conceived of a year earlier by engineers at General Electric, it represented a new design in receiving tubes (more about that later) and used the recently developed metal case(envelope), instead of glass. RCA was licensed to manufacture it and the first ones hit the market in 1936.

Originally thought of for audio use, it could give you 30+ watts of RF if used in a single-tube oscillator circuit. Not bad for a "receiving" tube - a general name used for things that were "low power" when thought of in comparison to broadcast radio transmitter power levels. It quickly became the most popular tube for ham transmitters for many years to come.

In a fairly short period of time, the 6L6 was also produced in a variety of glass envelopes. In fact the basic 6L6 went through many changes and upgrades as it went through life. RCA moved the plate connection to the top and the 807 was born. This power house, when given 600 volts on the plate could manage 60 watts without breaking a sweat. So much in use, the term "807" was once a popular ham nickname for beer. Technology marches on, and eventually the 807 was succeeded by the shorter 6146. The 6L6 saw it's life increased as the 6LQ6. Both of these tubes were quite popular, as well. Used in sets in kilowatt-level amplifiers with over 1,000 volts on the plates, they also showed up in pairs as finals in hybrid rigs in the 70's. I have a Handbook from 60+ years ago with a circuit for a one-tube 6146-based, 75 watt crystal-controlled transmitter. Don't try that with anything less than a FT-243 crystal...

The 6L6 also had lower rated siblings, the 6V6 (popular with Novices and used in some commercial designs like the Ameco AC-1 transmitter kit) and the 6K6 (very QRP-friendly). "Circle of Life" fans will note that 6L6's still enjoy use everyday, although primarily in audio amplifiers for those who like the glow and "warmth" of the the sound. You can find them at music stores for $50 a pair and up or at hamfests and Ebay for much more reasonable prices.

While I don't know the exact date the 6L6 arrived, March 14th is the 73rd day of the year. There's still time to celebrate the 6L6 by building a rig and putting it on the air that weekend. A straight key is strongly suggested. A quick perusal of the League's searchable QST database (you are a member, aren't you?) will turn up many design ideas and possibilities. Even if you don't have a spare 6L6, 6V6, 6K6, etc. to play along, they're easy to find. (In fact, I'm sure I have a spare for someone who wants to build his own rig in the coming weeks.)

Power supply? A 6 volt filament supply is easy - you can even use some wall warts for that. Coming up with 150 to 600 volts may be a bit more daunting, but if you have a tube-based receiver (makes a nice companion) you can carefully borrow some B+ for a low-power version. Or, go to the "everything we sell is a dollar, so please don't ask how much it is" store and pick up some 9 volt batteries. If you buy 15 packs of 2, you can click them together and come up with 270 volts for (wait for it) $15.

Hey, don't touch the ends to see if it's hot - it's still 270 volts and is dangerous if not respected! Pick up 15 more packs and you'll have a real rock crusher on the air.

If you've never gone on the air with tubes, here's a fantastic opportunity to mark "73 to the 6L6 Day" (or something like that). Remember, real radios glow.

W3JDR 's LTSpice NE602/SA612

Here's something we've needed for a long time: an LTSpice model for the ever-popular NE602/SA612 chip. Joe Rocci, W3JDR, developed this one back in December. You can download it, along with the LTSpice program (free!) from links on Joe's page:
http://w3jdr.ham-radio-op.net/ Thanks a lot Joe!

Speaking of Spice, Jim, AL7RV, has been e-cursing me for getting him involved with this highly addictive program. Jim has come up with an ingenious idea for making the simulation experience more realistic. I will tell you all about it in the next podcast.

The Reggie Works a DX Station!

There it is. Finally we see it. The famous Reggie of AA1TJ. With an awesome 80 milliwatts of 80 meter RF, Mike yesterday worked the Bahamas with his highly unusual rig. For more details visit Mike's always inspirational web site:
http://mjrainey.googlepages.com/reggie

WA5DJJ's QRSS Beacon: Immediate Success!

Here's a story that really captures the fun of QRSS, the way in which this mode can be both high tech/DSP-ish and low tech/minimalist at the same time. It also shows the global reach of the fraternity that supports QRSS. In SolderSmoke 101 I reported on the QRSS building project of Dave, Wa5DJJ. He was building a rig based on a design by the esteemed Maltese radio wizard Stan, 9H1LO (Stan appears in the SolderSmoke slide show -- he is the guy in the lab coat.) You'll recall Dave's comment on how upside down FSK might be useful in reaching our brothers "down under." Yesterday Dave put his new creation (see above) on the air, and posted a message to the Knights of QRSS Yahoo Group. In Belgium, Johan, ON5EX, saw Dave's message and decided to check W8LIW's receiver (via LIW's online grabber). Johan saw Dave's signal and reported the success to the Knights.
You can read more about Dave's project here:
http://www.zianet.com/dhassall/QRSS.html

Here is the e-mail exchange between Dave and Johan:

Tuesday, February 17, 2009 7:46 PMFrom:

"Johan_Smet@telenet.be"

To:

knightsqrss@cnts.be

Hi Dave, I can see your sigs are on the Ohio W8LIW grabber right now, with a little downward shifting. Well done! Your website truly reveals a keen QRP-er and homebrewer. BTW: I’ll be firing up my first RockMite (20) soon! 73, Johan on5ex

---

From: knightsqrss-bounces@cnts.be [mailto:knightsqrss-bounces@cnts.be] On Behalf Of David R. Hassall
Sent: woensdag 18 februari 2009 1:30
To: knights QRSS
Subject: [Knightsqrss] WA5DJJ on the air!!

Dear Gang,

First test of my QRSS 10.140Mhz MEPT. It should be around 1.060 on the waterfall. Power output is 122mW (All I could squeeze out of my poor little 2N222A final. Keying is up shift, at about 5 hz. I hooked it to my 30 Meter Inverted Vee off my tower. Apex is at 40 feet. I think I have it right and hope it doesn't blow up. We shall see when I get some reports. I will have pictures on my website as soon as I can get them there. Thanks for all the advice and help. This was a really fun project. Now to get a couple more built to get some others on the air.

73 Dave

------------------
BTW: I succeeded in putting Johan's grabber output onto this blog. Look at top of my right-hand column. If the sun is up over Europe, you should see my upside down FSK around the middle of Johan's screen. (He has the screen kind of split in two to allow more minutes to be displayed, so you should see me in the middle of both the top and bottom halves of the screen. ) You may have to hit the refresh button on your browser to get my blog page to pull down an update of Johan's grabber. Just think about how cool this all is: I transmit a 50 mw sig from Rome with a very minimalist rig. Johan receives it in Belgium using DSP software and puts the results on the www. I embed his output screen on my blog, which you can now see, almost in real time!

Comet Lulin

I don't think I will be able to see this one through the bright and murky skies of Rome, but I may give it a go. Sky And Telescope Magazine has a nice write up that tells you when and where to look. The best night for seeing this one are coming up soon:
http://www.skyandtelescope.com/observing/highlights/35992534.html

Armstrong's Regen (and lots more)

There it is. Howard Armstrong's regenerative receiver. Mike, KC7IT, led me to the wonderful website that has this picture, and much more. The site has all kinds of schematics and pictures and letters related to the work of radio pioneer Howard Armstrong. Check it out (you should probably take the tour by hitting the NEXT button on each page):
http://users.erols.com/oldradio/eha1.htm

I continue to work on my regen (part of the ET-1/FETer minimalist project). Jim, K9JM, says the raspy tone on CW signals is caused by FMing of the regen stage and prescribes a coil of higher Q. Thanks Jim.

SolderSmoke 101

http://www.soldersmoke.com

Superbowl Sunday in Rome. "Playing for Pizza." Spirals on the Piazza
Empire of the Air -- Gerbils Renamed
"Electrons on Parade"  Good RCA film about tubes
Minimalist Mania:
  ET-1/FETer transmitter built -- some problems
  New Minimalist Yahoo group
  AA1TJ and AA1MY make QRP History with tunnel diode rig
QRSS News:
  New beacons and grabbers in US and Canada
  K6HX and the lure of the whisperers
  Upside down FSK for VK/ZL observers?
Chip extraction tips (belated)
What "s.o.t." means.
MAILBAG:
Brad WA5PSA still jogging in Tulsa
Ted AJ8T and Paul VK5PH: Lake not named for Lee
Neil G7AQK HB mystery box
Doug WB5TKI on how to extract chips
Ron AA5RS advises Billy to stick with Linux
Bill AA0RQ uses the hard stuff
Scott on Heaviside:  Good guy or not?
Brent in Twin Cities: SWL Rockmite and SS lead to ham radio
Dan NM5DV building SDR QRSS rig
Jeff K07M listens while flying private plane
John W6TC has great article for Electronic Design
Edwin WA4YHL: Amateur Logic TV #23 is available
Dale WA5DJJ on the possible benefits of upside down FSK
Eddie G3JZO: Upside down FSK looks like laundry on the line!
Jerry NR5A has the minimalist bug

For the podcast go to:
http://www.soldersmoke.com

For the new SolderSmoke Store:
http://www.cafepress.com/SolderSmoke

Halted Specialties -- Our kind of store!

The New York Times recently ran a story about Halted Specialties, the Silicon Valley electronics store. Wow, almost makes you want to move to the area,
Here's the article:
http://www.nytimes.com/2009/02/05/technology/personaltech/05basics.html?_r=1

No need to move. They do mail order:
http://www.halted.com/

Looks like they are having a Vintage Radio event on Feb 21, 2009

It's an ANALOG world, after all......

John Edwards, W6JE, has written a really great article for Electronic Design. It is about analog circuitry, and the place of skilled analog designers in our increasingly digital world. John's article is filled with references to the kinds of issues that frequently pop up in the clouds of solder smoke that we work in, things like the need for a certain intuition about circuits, the need for deep understanding of how things work and why some things work and others don't. He mentions the element of craft and even "black magic" that plays a role in analog design and construction. In short, John's article describes "The Knack." He even manages to use the word in his article, and acknowledges (in his bio) that he has been a victim of Dilbert's disease ever since a childhood encounter with a Heathkit Sixer. Check out the article:
http://electronicdesign.com/Articles/ArticleID/20562/20562.html

You should also visit John's personal web site. We're about the same age, and we are both from New York City. John's page reminded me of another factor that might have put me on the path to solder smoke and hamfests: The 1964 World's Fair. Here's John's page:
http://www.gojohnedwards.com/

Thanks John!

"Empire of the Air"

Here's the book I've been talking about. Four Solder-stars. Strong on history and biography, but a bit light in the Knack department. Still, strongly recommended.

Minimalist Mania: AA1TJ-AA1MY QSL, New Yahoo Group

Above is the very classy QSL that Mike, AA1TJ sent to Seab, AA1MY, confirming the first ever tunnel-diode skywave QSO (see below for more details). Go Mikums!

In related news, Jerry, NR5A (who has also been bitten by the minimalist bug) reports the creation of a new Minimalist Radio Yahoo group:
http://groups.yahoo.com/group/Minimalist_QRP_Transceivers/

(Jerry and I have been attempting to translate some technical terms found in British schematics. Even though I lived there for four years, I admit to being stumped by "s.o.t." given with values for capacitors. Could this be "subject of test"? )

"ELECTRONS ON PARADE" A Film from the Radio Corporation of America

Gee-willikers! This RCA movie is the cat's pajamas! Really great stuff. The guy who posted it on YouTube said it had been sitting on his shelf for years, apparently just waiting patiently for the broadband Internet.

I hadn't realized how labor intensive tube production was. Looks like every one of those fire bottles was, to a large extent, put together by hand. The contrast with the way solid state devices are produced is really striking -- the tubes seem like the product of artisans. And they somehow just seem to be more homebrew-friendly than modern solid-state devices.

Don't miss Part 2! Here we see "heroic hams" in action, saving people from serum shortages during floods, etc. Watch the policeman with the Tommy-Gun almost run over the kid on the bicycle. Yikes G-man, that was close!

The date on the film is 1942, and judging by the number of women shown working in the factories it does seem like a wartime film, but I was surprised by how infrequently the tube's role in the war effort was mentioned.