Podcasting since 2005! Listen to Latest SolderSmoke

Friday, May 27, 2016

Pete's Beautiful New Blue Rig


A thing of beauty.  

Read about it here:   http://n6qw.blogspot.com/

Thursday, May 26, 2016

Listening to New Zealand on the Barbados RX via the Gray Line (40 meter CW)


John: 
For the last couple of mornings you have been coming in quite strong on 40 meters around dawn here.    Attached is a short video from today.  I am listening with a homebrew superhet receiver:
73  Bill N2CQR

Hi Bill,
Thanks for sending the video clip.
It’s really made my day!
I’ve sometimes wonder what I sound like at DX now I know.
The IC7410 sounds quite respectable and the sending is reasonably decipherable.
Interesting about the receiver.
The signal seems to stand out well from the noise.
Really well done. But then that’s what ham radio is all about.
We all enjoy radio and  we all like to enjoy the various aspects to the hobby.
Modes, antennas ,QRP whatever.
It’s great fun.
It would be good to have a QSO. perhaps some time soon?

Thanks again,

Very Best 73,
 John ZL1ALA

Wednesday, May 25, 2016

Swedish Michigan Mighty Mite Beacon Project


sTef DL1FDF/VY1QRP alerted us to this multi-band Michigan Mighty Mite beacon project out of Sweden. They certainly have some fine looking rigs! 

Check out the reports:
http://www.radiorud.se/fyren.php






Tuesday, May 24, 2016

Audiophoolery



Hi Bill:
 

   I remember reading an outraged letter in a stereo magazine back in the 80's, right after CD's came out.  The writer had condemned a particular CD player for having a single digtal-to-analog converter that was time-shared between the two channels, consequently inducing an "unlistenable" phase error in the audio.
    An engineer (and I hope a ham!) wrote in to observe that this was indeed correct, but helpfully noted that the phase error could be corrected by moving one of the speakers about a half inch farther away from the listener. That's noodling!  :-)
And you might enjoy this article:
...Some audio scams are so blatant you wonder how anyone could fall for them, like a replacement volume control knob that sells for $485. The ad copy proclaims, “The new knobs are custom made with beech wood and bronze … How can this make a difference??? Well, hearing is believing as we always say. The sound becomes much more open and free flowing with a nice improvement in resolution. Dynamics are better and overall naturalness is improved.” ...
  James Randi, magician and hoax-buster, had a standing offer of $1M to some makers of "paranormal" audio equipment, like $700/foot cable, if they could prove it was better in blind A/B testing.  Nobody took him up on it.

 73,
  Bob

Saturday, May 21, 2016

SolderSmoke Podcast 187: 2nd Anniversary N6QW. Dayton. Bench Reports. Mailbag



SolderSmoke Podcast #187 is available:

http://soldersmoke.com/soldersmoke187.mp3

Second Anniversary of Pete Juliano's arrival on the SolderSmoke Podcast.

Dayton and FDIM underway

Bench Reports:
Pete:
-- Repurposing old Circuitry
-- Pete's small Display
-- New Transmitter
-- LBS in Japan and at Dayton

Bill:
-- S38-E   The lipstick has worn off.
-- Reduction drive for the Mighty Midget's Mate
-- Back to the Barbados Barebones Receiver:
    Which LO to use for 40 Meters with a 5 MHz IF? 
    Sideband Inversion and "Lower Sideband" filters.
    Eradicating WWV with parts from AA1TJ
    Improving VFO stability
    A bandspread/bandset arrangement with fixed caps
    Soul in the Old Machine

"The Amateur is FRIENDLY..."

MAILBAG





Thursday, May 19, 2016

XQ6FOD -- A GREAT Knack Story from Chile


Greg VK1VXG sent me this link.  I had a blog entry on this a few years ago, but I didn't do it justice.  This is a truly amazing and inspirational knack story, the story of Manfred, XQ6FOD. So many lines from this page resonated with me.  For example:

I always regretted having disassembled this radio. It was so nice, so compact... Everything was hand made, there was not a single right angle in it... I felt like a murderer after destroying it. But, I needed the parts...

I designed this thing during a family summer trip into Chile's beautiful deep south. The VFO part was designed on Chiloe Island, the IF and receiver circuit took shape at Futaleufu, Rio Cisnes, Puerto Aysen and Coyhaique, while the difficult RF power amplifier work was done on the return trip via Bariloche in Argentina. So this is an international design!  Once back at home, for the first time in my life I did a thorough computer simulation of the whole thing. I hacked around the program for two weeks, and then my poor Atari had to spend another two weeks crunching numbers. It found some potential problems. I improved gain distribution, corrected mistakes, and then went straight to designing the printed circuit board, without doing any real-world test.

Check it out:



Monday, May 16, 2016

Oz QRP2QRP From Mt. Bullfight, Pyramid Hill, and Melbourne's Chelsea Pier


Saturday, May 14, 2016

A Lot of Soul in the Barbados Receiver

After a rather frustrating period working on the Hallicrafters S38-E, I decided to do something different, maybe work on something that isn't known as a "widow maker."    So pulled off the shelf an old Doug DeMaw Barbados Superhet Receiver.  "Barbados" sounds much nicer than "widow maker."  This design and this particular receiver have quite a history: 

-- DeMaw presented the receiver in the June 1982 issue of QST.  It uses six 40673 dual gate MOSFETS, an op amp for the audio, and a 250 Hz crystal lattice filter at 3.579 MHz using (YES!) colorburst crystals.  The local oscillator was a VXO. Doug's was for 20 meters, but his article provided a lot of info on how to put it on other bands.

-- I built one in 1997, building it for 20 CW.   That project is described here:

-- Sometime around 2000 I bought another one.  This one had been built on a FAR Circuits board by Dale Parfitt, W4OP.  Dale had used 5 MHz rocks for the filter and had used a varactor tuned circuit for the LO (with a DC-DC converter to increase the range).   I put it aside.  It sat on shelves in several countries for a number of years.  (I even have a THIRD one, a partially stuffed board that Michael Hopkins (the guy who wrote those great stories about Frank Jones coming back to life to retake the 5 meter band)).

-- I started working on it again around 2005. We were in London by then.  I put it on 17 meters using a capacitor-tuned VXO running up at around 23 MHz.   I did a quick and dirty broadening of the crystal filter by simply changing the capacitor values in the filter.  This worked, but obviously it needed refinement.  As I asked questions about this receiver, Dale Parfitt came to my rescue.  It took us both a while to realize that he was advising me on the receiver that he had built.  That was kind of cool.

-- I used the receiver with my first homebrew SSB transmitter.  I had them both running with separate VXO's, with crystals switched from the front panels.  I'm sure there were no other rigs like this on the air anywhere in the world.

-- By 2011 we were back in the US and I put my old homebrew SSB station back on the air.

-- In October 2014 I was building my first BITX rig.  I built it for 17 meters using a 23 MHz VXO.  I took the crystals out of the Barebones receiver.  Later that month I used an Arduino/AD9850 DDS arrangement as a digital crystal replacement: 
It worked, but it looked hideous.

-- By January 2015 I had learned a lot about how to characterize crystals and build filters.  I decided to take a shot at properly expanding the frequency response of the 5 MHz Barbados filter.  I measured the characteristics of the crystals and got the proper cap values for a 3 kHz filter.  When I tested it, the width seemed fine, but the ripple was more than I had expected.  Kind of disappointed I moved on to other projects.

-- Which brings us to today.  Escaping from the S38-E, I decided to put the Barbados receiver on yet another band.  With sunspot numbers in decline, I opted for 40.  And I wanted this to be an analog, L-C VFO project. No DDS, no PLL.  It would be all L and C for me, thank you! First I played around with the idea of running the VFO up at around 12 MHz, subtracting the 7 MHz sigs to get to the 5 MHz IF. But then I did a sweep of the filter.  First, there was a nice surprise -- the width AND the ripple were fine, just what I wanted (I must have had a measuring problem when I checked the ripple before).  And the skirt was MUCH steeper on the high side than on the low side.  This is why these filters are often called Lower Sideband filters.  You get better opposite sideband rejection if you use them as LSB filters.  

With the skirt situation in mind, I realized that running the LO at 12 MHz would not be a great idea. Our rule of thumb tells us that if we SUBTRACT the signal with the modulation from the signal without the modulation, we'll get SIDEBAND INVERSION.  So 7 MHz LSB would end up as 5 MHz USB.  Not great.  Plus, it is hard to get a VFO stable at 12 MHz.

So I opted to run the LO at around 2 MHz.  There would be no sideband inversion, and it would be easier to get the oscillator stable.   Wary of the threat of harmonics and spurs, I ran the receiver for a few days using an Arduino AD9850 at 2.125 MHz - 2.300 MHz.  It worked fine.

I now have the receiver running with a real Colpitts VFO.  The inductance is provided by an adjustable, shielded coil at around 1.5 uH (it was on the board) in series with a 3 uH toroid (type 6 yellow).  The feedback caps are at 2200 pf with a 1020 cap in series.  The main tuning cap is a small air variable with 73 pf max.  This only lets me tune about 40 kHz of the band, so, in a variation on the old Main Tune -- Bandspread technique, I have a rotary switch that adds capacitance in parallel with the main tuning cap.  I can now tune from 7.141 to 7.300.  The tuning rate is fine and I didn't have to mess with a reduction drive. 

More Barbados receiver blog posts here:
http://soldersmoke.blogspot.com/search?q=barbados

Kind of amazing that DeMaw designed this thing 34 years ago.  A lot of soul in this old machine.   




















Thursday, May 12, 2016

The Solder Is Smoking at N6QW!

It is very good to see the solder flowing again in the Newbury Park Laboratories of Pete Juliano, N6QW.  Check out that postage stamp-sized display.

More details on Pete's newest rig can be found on his blog:

http://n6qw.blogspot.com/2016/05/a-new-ssb-transceiver-from-n6qw-with.html



Tuesday, May 10, 2016

Putting Junk Mail to Excellent Use: Tony G4WIF's Proto-boards


Tony's Version of Audio Section of N6QW's LBS Receiver



Tony Fishpool, G4WIF writes:


I’ve been intrigued by Pete’s matrix pad method. Of course, few of us have the machinery to mill them as Pete does, but etching is a possibility. Now some of Pete’s boards clearly have a lot of noodling behind them. His boards are quite big with little areas of pads and space between. The layout for the whole project has clearly been considered in advance.

I wanted a board that I could make modular, take little time to etch and adapt for the circumstances. These “proto-boards” are the result.

The project is Farhan’s “sweeperino” and one board is for the Si570, and the other the AD8307.

The Si570 board is now complete and working:




The PCB method is pure Chuck Adams. His videos on YouTube describe the toner transfer method better than I could.

The only difference for me is that my glossy paper comes free from travel agent brochures.

Just express a passing interest in Viking River Cruises and you will never pay for PCB paper ever again!

There is a free printing only version of the software I use, so if SolderSmoke listeners want to use the proto-board design, I will happily email them the files.



Kind regards
Tony G4WIF

Monday, May 9, 2016

A 12AU7 Atop a Raspberry Pi

http://makezine.com/2016/05/06/warm-tube-tone-is-just-what-the-raspberry-pi-has-always-been-missing/

I don't know what to say.   One moment I find myself thinking that this could represent "the best of both worlds."   A minute later I'm thinking that this thing is a horrible chimera.  And it has a whiff of audio fool-ism about it, don't you think?  Will it work better with oxygen-free cables and gold-plated fuses? 

Still, overall -- pretty cool.

Friday, May 6, 2016

Polyvaricon Reduction Drive

Oh man, we need more of these.  Many more.  Unfortunately, this may be the only one.   I pulled this out of an old piece of mystery-gear given to me back in 1994 by my friend Pericles HI8P.   Look at that:  dual turning rates, solid construction, and very small.   This device seems destined to go into my W4OP-built Barebones Superhet (in the background).
Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column