Happy New Year! Straight Key Night

 

For the first time in years I got on the air on New Year's eve.  I fired up the HT-37 and Drake 2-B on 20 meters last night right at 0001 UTC  (well, with these rigs I should say GMT!).  There was a moment of stress when, as I was trying to adjust the key, the whole thing fell apart and the little ball bearings spilled out.  Yikes!  It was as if the radio gods were trying to tell me something.  It took me a few minutes to re-assemble my straight key, then I called CQ.  The HT-37 puts out a lot more power than I normally emit,  and it caused the Carbon Monoxide detector to go off, sparking a minor panic among family members.  (See, this never happens with QRP!)  With that resolved I had nice QSOs with K5KFK in Texas, W6VNR in California, and N1WPU in Maine.  This morning I worked WA0ZDE in Missouri.  The old HT-37 was drifting a bit, but Rick said he kind of liked that.  (I put a muffin fan on top of the transmitter -- that should settle it down a bit).   By the way, my key is a bit unusual: it is just a cheapo key, but I have it mounted on the base from a Vibroplex bug.  I never mastered the Vibroplex, and ended up giving the bug parts to HI8G in Santo Domingo -- Gustavo planned on using them to fix another bug that had been given to him years before by Fred Laun (K3ZO). 

 

Rick, WA0ZDE ( who I talked to on 20 this morning) sent me a VERY SKN photo collage (see below).  I see that Rick also tends to hold onto his gear for a long time. 

 

HNY to all!   GL in 14.  73! 

 



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SolderSmoke Podcast #157: Peter Parker on Phasing Rigs

SolderSmoke Podcast #157 is available for download.
http://soldersmoke.com/soldersmoke157.mp3

December 27, 2013

-- Santa Report:  Rigol Scope at SolderSmoke HQ.  Kites at VK3YE.
-- Project updates:   Bill's BITX 40/20 build. 
-- Peter finishing up BITX40  (in a big box)
-- BITX 17 (5 watts SSB) works JA, ZD7, ZS!
-- The mystery, elegance, and gentleness of phasing SSB
-- Phasing explained in 1970 ARRL SSB book
-- Phasing SSB: From Hallicrafters HT-37 to SDR
-- The SP5AHT Phasing Rig
-- I & Q for you:  The Binaural Experience
-- Direct Conversion receivers and Software Defined Radios
-- Simple DC receivers plugging into sound cards 
-- The joy of receiver building
-- 144 MHz aircraft bounce (Melbourne to Sydney)
-- VHF Across The Great Australian Bight  

HAPPY NEW YEAR TO ALL!

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Santa Arrives at SolderSmoke HQ! Rigol and Black&Decker

Santa Claus obviously heard my distress call when the TEK 465 gave up the ghost.  This morning it was replaced by a RIGOL digital scope.   I'm going through the tutorials.  Wow, lots of features.  A Black&Decker jig saw also arrived -- this will help in my cabinetry efforts. 

Last night just before dinner I talked to Kiyo, JH1MDJ, in Tokyo on 17 meter SSB with the 5 watt BITX.   I kind of broke through a small pile-up and we then had one of those "please repeat your power level... I can't believe that is 5 watts to a dipole" conversations.  

Happy Holidays to all!

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

How they took the iconic Apollo 8 Earthrise Photo (Amazing Video)

I was ten years old and totally obsessed with the space program.  This video brought back a lot of the magic. Wow. You really have to see this one.


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Where to send all those LM386 chips: Make them BEAM robot brains!

Over in the BITX20 yahoo group there have been some comments about the shortcomings of the widely used LM386 audio amplifier chip.  Many people don't like it because it is noisy.  I don't like it because it is a chip. (In my BITX rigs I have replaced it with a simple discrete component audio amplifier.)  So this morning I was pleased to find this video on the Maker blog that presents a very good use for all those LM386 devices:  We can turn them into robot brains!

Make's video and web page on this project are both very good.   One paragraph in the page kind of captures the reasons I dislike the LM386:

How It Works

The core of the “Herbie” circuit is the LM386 power amplifier chip. To simplify a bit, we can think of the chip as a “black box” with inputs and outputs that respond in predictable ways, and don’t have to completely understand what’s going on inside. 

 http://makezine.com/projects/sunbeam-seeker-bot/

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Christmas Eve Fessenden Memorial Broadcast on 486 KHz

Imagine it is Christmas Eve, 1906 and you are on the air, listening to the harsh buzz of Ol' Spark Morse Code.  Suddenly, in the headphones you hear a human voice and music.

Brian Justin  has set up an experimental station that recaptures that magical "birth of radio telephony" moment.   He will be on the air this Christmas Eve, Christmas Day and New Year's day.   Here is what W4DEX heard during last year's event:

http://www.w4dex.com/500khz/wf9xih/wf9xih_24dec11.mp3


Experimenter to Honor Early Wireless Pioneers with Longwave Transmissions

Fessenden

As he has over the past several years, Brian Justin, WA1ZMS/4 -- as experimental station WG2XFQ -- will transmit voice and music on 486 kHz on Christmas Eve and Christmas Day and again on New Year's Eve and New Year's Day. Transmissions will begin at 0001 UTC and end at 2359 UTC. Justin, who may be better known for his microwave exploits on ham radio, will use an AM audio loop modulating his vintage-style, homebrew transmitter to honor Reginald Fessenden's Christmas Eve 1906 AM voice transmission.

WA1ZMS constructed his MOPA transmitter from 1920s-vintage components. [Brian Justin, WA1ZMS, photo]

"While his original transmissions used a set of carbon microphones in the antenna lead to modulate the signal," Justin explained, "WG2XFQ will be utilizing true Heising modulation in honor of Raymond Heising, who developed this early form of amplitude modulation during World War I.Justin constructed his 5 W master oscillator power amplifier (MOPA) transmitter using 1920s-vintage components. He said a modern 500 W FET linear amplifier allows him to meet his WG2XFQ ERP limit of 20 W. An RF engineer, Justin collects pre-1920 wireless gear and has a World War I Heising-modulated aircraft transmitter he's planning to restore. Justin was an active participant in the ARRL's WD2XSH 600 meter experimental project.

(From the ARRL Newsletter)

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BITX 2040 Build Update #2: Of Spreadsheets and VFOs

I continue to tweak the capacitors in my new BITX 20/40 VFO (scroll down to see it).  On Sunday I added a little relay that will switch in some additional capacitance to move the VFO about 500 kHz.  Without the additional cap, the VFO will be on frequencies suitable for 40 meters -- with the additional cap it will be on frequencies needed for tuning 20 meters. 

I calculated that I'd need an additional 220 pf to make this shift ( I later went with 100 pf).  In went the needed cap and relay.  It worked.  But there was a problem:  On 40 I had the desired 175 kHz frequency range.   But I found that with this arrangement on 20 I could only cover 95 kHz.   Obviously my variable air cap with 44 pf in series was being "diluted" by the additional 220 pf being switched in by the relay -- with the additional capacitance, the change in total capacitance produced by the variable cap (with series cap) was smaller in the 20 meter range than it was in the 40 meter range. 

Clearly, one solution was to play with the value of the cap that I had in series with the variable cap -- increasing it would increase the freq spread (both on 40 and 20).  But how much should I increase it?

By this point I was getting tired of all the manual calculations.  Time for a spreadsheet! I created one, and threw in the values of all the caps and of the coil,  and the resonant frequency formula.  I set it up to display and the resulting freq coverage. 

The freq ranges in the actual ham bands is a bit off -- there may be some stray capacitance and inductance in the circuit that is not being captured in my numbers.   But the important thing was the spread.  The spreadsheet allowed me to see that with a 100 pf cap switched in by the relay and a 74 pf cap in series with the variable, I could cover 180 kHz on 40 and 123 kHz on 20.  That's OK.  This little exercise shows the usefulness of spreadsheets in dealing with this kind of calculation.

You can see my spreadsheet here:
https://docs.google.com/spreadsheet/ccc?key=0Ak4BJL1-oWiJdElieDY5Y2xVWUtSNDl0anRYLVBBeGc&usp=drive_web#gid=0

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20