How many Drake 2-Bs? The German Tank Problem

I have #11,976!
-------------------
Hi Bill,

I was just listening to your latest soldersmoke podcast and your
discussion about how many Drake 2Bs were made. Without knowing the
exact serial number for the last Drake 2B before the Drake 2C was
made, you can estimate what that number might have been by knowing a
few of the real serial numbers that are being used by people today.
This is a mathematical problem related to the somewhat famous "German
Tank" problem. Check out:
http://en.wikipedia.org/wiki/German_tank_problem.

If you were to ask your listeners to report to you their Drake 2B
serial numbers you could estimate the largest serial number there ever
was from the formula on that wiki page. This could be a fun exercise
:) I've never had a Drake 2B so I can't contribute. But I could do the
estimate for you if you gave me the numbers.

Cheers and 73

Scott (K6AUS)

Alan's "Scopes 4 Dopes" (present company excluded, of course)

Hi Bill,

As a follow on to the Scope 4 Dopes class that I told you about (email below - and thanks for the shout-out in #133), I have put a few more videos on YouTube. One is on the use of the Delayed Timebase feature available on the more professional analog scopes - probably not of much interest to you. But, the other two are on taking a little bit of a tour of the RF signal path of the TenTec 1254 Dual Conversion Shortwave Receiver kit that I built over the Christmas vacation. I thought these might be of interest:

(I promise - these are not as long as the 2hr Scopes4Dopes tutorial video!!)

The tour through the 1254 with a look at some of the signals along the RF path (~12min):

http://www.youtube.com/watch?v=dZNN5RnOdt8

and a short one looking at the modulated and demodulated 2nd IF on a live shortwave signal (~2min):

http://www.youtube.com/watch?v=pzLA_lRdmPI

Enjoy.

73,

Alan W2AEW

EDN Article on April 1 and other Pranks

Bob, W8SX, alerted me to this gem. Geek thrills.

http://www.edn.com/blog/Anablog/40759-Pranking_bosses_friends_and_competitors_.php

Here is one of my favorite segments (it involved a 'scope and a soldering iron):

You should beware of prank escalation. Len Sherman, application engineer at Maxim recalls a prank exchange with Jim Williams when they were at MIT. As he loves to do, Williams had bought an old broken oscilloscope and worked on it all day, bringing it back to life and perfect operation. After Williams went home for the night, Sherman put a piece of toilet paper under Jim’s oscilloscope graticule. The paper was unnoticeable, but made the scope trace fuzzy. It looked like a focus problem. Jim went crazy the next day trying to fix this problem. He had the covers off and was measuring all the high voltage circuits. It took a few hours before he found the paper.

To retaliate, Williams took the hinge pins out of the lab door and tied a rope to the doorknob that he pulled back into the room, threw over a beam in the ceiling, and tied to 100 pounds of ballast. The next morning Sherman put the key in the lock and turned the knob. The entire door left it hinges and glided, upright, back into the lab about 10 feet. It then stopped and fell over. “It looked like something out of a Stephen King movie,” recalls Sherman.

Sherman then rigged up a water nozzle to a photo-switch triggered by the lab lights. He rigged a soldering iron with coil of solder around it used as a fuse, to time out the prank. Sherman didn’t want to flood the lab, just run the water nozzle for a minute or so. Williams got wet.

20% off on SolderSmoke -- The Book

Today only. Use coupon code LUCKY and take 20% off.

For more info on the SolderSmoke book see http://soldersmoke.com/book.htm

Sinclair 1000 Computer For Sale

Take a walk down (low) memory lane...

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320699873588&ssPageName=STRK:MESELX:IT

SolderSmoke Podcast #134

http://soldersmoke.com/soldersmoke134.mp3

May 15, 2011
New "Ikea" microphone
NOVA QRP Club
WSPR T/Rouble resolved
Finishing up Rome WSPR rig
Easy-Peasy on Asus eee-PC
Space Station Packet Beacon
Boatanchor News: DX-100, HT-37, "CQR" anchors, 75 meter antenna Drake 2-B history interview by W8SX
Lew McCoy and Ernest Hemingway
Ade Weiss, QRPoetry and Ade's new book
Regen theory
MAILBAG (with a focus on New Zealand)

Landing on Titan to the Sounds of Saturn

These are real images from the Huygens probe. And the sound is apparently from the radio signals generated by Saturn. I agree -- it sounds nicer than Jupiter!

Euro Zone: SolderSmoke Kindle-book Now Available

SolderSmoke -- Global Adventures in Wireless Electronics is now available on the Amazon.de (German) web site. Payment in Euros.
https://www.amazon.de/dp/B004V9FIVW

WONDERMARK! (Comics with the Knack)

As part of our occasional series on Knack-related comic strips, today we present Wondermark. This link will take you to the first page: http://wondermark.com/tink1/ From there, look for the little "NEXT" hand on the right of the comic. There are eight. All of them are gems. Also, be sure to check out the author's bio:
http://wondermark.com/about/

WSPR -- THE MOVIE!

VK2TPM made some nice videos of the Weak Signal Propagation Reporting System (WSPR) maps over time. Its kind of fun to watch the propagation shift from trans-Atlantic to trans-Pacific.

More: http://www.youtube.com/user/vk2tpm#p/u/4/U1sBGZzNv8s

T/R Success with WSPR

Thanks to everyone who sent in advice on my WSPR t/r troubles. I now have it all sorted out. In the image above you can see the cable from the serial port that carries the RTS T/R signal from the computer. It goes to a switching transistor that controls a relay that in turn switches the three relays that actually do T/R for the rig. One question: On the Linux computer the RTS signal seems to switch between +5 and -5 volts, but on the Windows machine it was +10 and -10. Why?
I'm really pleased to have the computer interface working. It is kind of neat to bring together the complex technology of the computer and the simple technology of a DSB/Direct Conversion rig.

Five Planets Visible in the Morning

The good folks over at spaceweather.com have once again alerted us to an important astronomical event: During May, early risers will be treated to a conjunction of Mars, Jupiter, Venus, and Mercury. (The fifth visible planet would be the one you are standing on!) The Moon is thrown in as a bonus. The photo above was taken by Liz Gleeson on Magnetic Island (Australia) -- what a great location!