A Saw the Southern Cross (Crux) This Morning (first time in 30 years!)

You can see it (above) in the picture I took this morning, with my Iphone. 

I think I last saw this important constellation more than 30 years ago.  From my observation log: 

DECEMBER 9 1994. MORNING. Went to Parque Mirador Sur near Hotel El Embajador at 5 a.m. Confirmed that I have been looking at the Southern Cross. Below Corvus, Head of the Cross is on a line from Alpha and Beta Centauri. Base of Cross is "three thumbs" from horizon. I calibrate my thumb with Mars and Regulus at 2 degrees. That puts base of cross at 6 degrees off horizon. My Horizon is (90 -18.5 = 71.5 South. So 71.5 - 65.5 BINGO! Agrees with star map declination for Southern Cross. Also Right arm of cross is faint as indicated on star map. Alpha and Beta Centauri off tothe left. Alpha looks red. Beta seems to have two other stars around it. Eureka: Following the line from Alpha and Beta Centauri to the head of the cross, I found a very distinct circular cluster. I think this is the Jewell Box - NGC 4755 (open cluster). Still trying to figure out the constellation (Argo?) that lies to the right of the cross. Looks to me like the false cross. It is bigger than the Southern Cross. Mine seems to have a cluster off the right arm and the left arm has a dimmer star near it. A good morning! (LATER FOUND THAT MY CLUSTER WAS GLOBULAR CLUSTER RNGC 5139. I HAD MISIDENTIFIED ALPHA AND BETA CENTAURI.) 

Here is what Heavens Above predicted for this morning from Punta Cana: 

 

 

Steve G0FUW talks Homebrew and Kits with Charlie NJ7V

Our homebrew direct-conversion receiver challenge (see below) has led to a discussion of the differences between homebrew and kits.  Our intent in designing this rig was to come up with something that was simple enough to actually homebrew (that is the challenge:  homebrew it!) .  Building it from a kit would be something different.  I like the way Charlie and Steve talk about the differences between homebrew and kits in this video.  Around 33:49 Charlie mentions that after a while you just get good at building kits.   Steve points out that building kits is a bit like "painting by numbers" (a great metaphor).  Steve then goes on to talk about the formation in G-QRP of the "scratch-built group." Steve tells us that he has built some 84 radios.  Steve talks about "the joy of building it yourself" (43:49)

Steve gives a very kind shout out to SolderSmoke at around 23:58.    The references to Tony G4WIF and Ian G3ROO were also very nice. And there are many great mentions of Pete Juliano N6QW. 

And remember:  If you are not a member of G-QRP you are just wrong!  Join here:  https://www.gqrp.com/join.htm 

Thanks Charlie and thanks Steve! 

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November 13, 2024

Bill's appearance on the Ham Radio Workbench.  (Bill made some overly harsh comments about radio rejuvenation, and was trying to make amends.)  But now we throw down the gauntlet.  WE CHALLENGE the HRWB guys to build -- to homebrew - our TJ DC RX.  They will experience JOO, JVO and the elite status that comes with having built their own ham radio receiver.  And if they go on to build a 10 minute transmitter, they can use it for CW contacts.  Like on POTA (Thomas!)

December 13, 2024: 

Bill was on Ham Radio Workbench: https://soldersmoke.blogspot.com/2024/11/bill-n2cqr-appears-as-guest-on-ham.html  Our challenge to HRWB.  Gauntlet thrown down... OUR CHALLENGE HAS BEEN GRACIOUSLY ACCEPTED!     We now extend the challenge to the entire SolderSmoke community: Build one of these:  https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

Homebrewing is not for the faint of heart!  Accept the challenge!  Build stuff! 

A Tale of Woe -- Troubleshooting my 15-10 Rig in the Dominican Republic

-- Problem first showed up as a low level oscillation in the background.  Annoying. 

-- I suspected the simple AF amp from the TJ DC RX project was oscillating.  Wasted a lot of time. 

-- Isolated the problems by cutting off all of the RF input to the SBL-1 mixer. 

-- While watching the carrier osc signal, noticed that the hum appeared as the waveform got fuzzy. 

-- I had used the osc/product detector circuit from the BITX 20. 

-- I had added an amplifier stage to get the signal to higher level. But it was poorly designed. 

-- After some struggle, I decided to rebuild the osc/mixer board. 

-- Redesigned amplifier stage using LTSpice. 

-- Changed from an SBL-1 mixer to a singly balanced mixer like in the BITX 20. 

-- This worked well.  Hum disappeared. 

-- But I had neglected to put the .001 uF cap to ground from the AF port! Thus the cartoon! 

-- This is a very important cap.  Circuit was a lot more balanced with this cap in place. 

-- Noiticed that output on 10 was only about 25 watts PEP, while on 15 it was around 100. 

-- Checked input to final amps.  Input on 10 was a lot lower.  

-- Tweaked the 10 meter bandpass filter and got the output on 10 up to about 80 watts. 

Re-Built board for carrier osc/BFO and mixer for TX and RX

Scott KQ4AOP's PTO Coil Forms for the High-School Direct-Conversion Receiver (Video)

Scott KQ4AOP listened to amateur radio signals for the first time using a homebrew receiver.  That is really something.  See:  https://soldersmoke.blogspot.com/search?q=KQ4AOP

Scott then very kindly offered to 3D print the coil form for the PTO that is one of the four stages of our High School receiver project.  The above video shows the coil forms being 3D printed on Scott's machine, and explains where some of them are going. 

Dean KK4DAS will soon launch a video and e-mail-based build of the receiver.  Stay tuned. Dean's series should clear up any remaining questions about how to build this receiver.  As Scott so rightly said: 

"This was my first receiver build and, it was great fun. When you finish the build and prove you are able to tune through the band, you are welcomed into the secret society! The build is the initiation. I am happy to print and ship the PTO if needed."  

Donnie WA9TGT's Direct Conversion Receivers

Donnie WA9TGT writes: 

I recently built my first basic 40 meter (DC receiver) from http://www.qrpkits.com/  that uses the common SA602 & LM386 chip combo with Varactor diode tuning. I didn’t want to scratch build a DC Rx simply because I first wanted to build up this simple kit with its included PCB and at least play with it a little just to see if it was something I mite wanted to further pursue. I’ve since decided yes I want to, even with all a DC receivers short comings. It’s was nearly as rewarding hearing my call being sent back to me for the very first time coming through this little DC Rx after calling CQ as it was back in 1966 during my very first Novice contact. 

Donnie's inspirational QRZ.com page:  https://www.qrz.com/db/WA9TGT

Happy New Year from the Dominican Republic! SKN from HI7/N2CQR

As you guys know, here at SolderSmoke we are all about tradition.  Things like homebrewing, thermatrons,  crystal radios,  April 1, and even (at least once a year), MORSE CODE.   This morning was the morning for morse.  Straight Key Night my friends.  I got on the air with a QMX transceiver that my friend Bob had given me, and with a Sankar VU3XVR key that Farhan gave me a few years ago.  It all worked great.  First contact was with DF0W, then in quick succession WA3KCP, K3CQR, and K4DY.  All 5W 20 meter CW with a 1/4 wave vertical.  TRGHS. FB. HNY!

2 days of RBN spots, QMX barefoot to vertical at HI7/N2CQR

December 31, 2024 -- January 1, 2025 

Other Kinds of Workshops -- Making a Clock with a Lathe

Somehow, this video fits well with the SolderSmoke theme.  It may be that Uri cheerfully acknowledges that the lathe can kill you (the same is true of much of our gear).  Or it may be his repeated use of the term "Bob's your uncle" (has he been listening to SolderSmoke?).  Whatever the reason, this beautiful video fits here.  This is from Uri Tuchman's channel:  https://www.youtube.com/@urituchmanpigeon.  Uri is in Germany.  Thanks Uri! 

Derek N9TD's Magnificent Build of the TJ Direct Conversion Receiver

 

I think it is magnificent.  Derek N9TD fought his EE tendencies and recognized that the perfect can be the enemy of the good.  So he went ahead and built this receiver pretty much as we intended it to be built:  Four stages:  BP filter, PTO, Diode Ring Mixer, Super-simple AF amp. 

He went several steps further and added a fixed coil to slow down the tuning and keep it in the 40 meter band.  He added an RF gain control.  And he went with a steel (vs. brass) screw.  But these are all things that I myself have done.  (We still advise people to build it the simple way first.) FB Derek. 

The challenge is still out there.  The gauntlet has been thrown down.  Derek's completed project shows us that this project is entirely do-able.  Do it!   

Derek wrote: 

Bill, 

Let me introduce myself, I am a recent electrical engineering graduate from Purdue and a long-time listener of the podcast. I want to thank you and Pete for being one of the reasons I chose to pursue my degree in the first place. I'll admit that in the more difficult stretches of getting my degree, I often pulled out the podcast to be reminded of the fun that can be had with radio and electronics.

Until recently I had to hang my head low along with the majority of the other 'appliance operators' out there having never built anything with my two hands that can be used to pull signals out of the ether.

 I am no stranger to building projects, PCBs, and melting solder but I usually chose to either stick to the dreaded digital domain or focus on antennas, filters, and other ancillary equipment. The logic being that I like to have a "known good" radio for the shack and that I would focus on other equipment to supplement the radio. I still follow this logic when I want to contest and we all know that antennas are well worth the effort, I've just finally had enough of being an appliance operator and have your podcast to thank for the extra push. 

I had been following the original effort of the TJ DCRX with interest from the start and earmarked this project as one I would like to build based on its inherent simplicity and good performance. However, the demands of school and a recent (at the time) abortive attempt to build an AM superhet with an SA602 the year prior made me  (I got as far as feeling the joy of oscillation but regretfully petered out after that) put this one the backburner for about two years until December 2024.

By coincidence, I independently decided to start this project just before your show with the HRWB folks and the gauntlet being thrown down, which has spurred many to build this receiver. It has been great to see the extra coverage on the receiver, and the commentary has been very insightful for someone trying to build this for the first time and with as many of the "improvements" as possible. 

For better or for worse, I'm the type of guy who wants to understand the "why" behind all the design choices and, from there, try to incorporate as many lessons and improvements as possible to make the "best" version possible. I'm not saying I make the best version of anything, but it's just a quirk of the way I think and justify doing a project. It always has to be "this and some additional improvement;" otherwise, I would decide against doing it. 

Rambling aside, I ended up building the DCRX, adding the RF attenuator from N3FJZ's website, and incorporating the lessons you learned after experimenting with improving the tuning on the PTO. I added an external series inductor wound on a dowel rod and used a zinc-coated steel screw as opposed to brass. I found that this gave solid tuning performance across 40m and was easy enough to tune in CW or SSB signals (after 3D printing a large knob for the PTO bolt). Alan W2AEW's video on mixers was a great tutorial to use to verify that my mixer was mixing. With the radio assembled I was treated to the joy of hearing my receiver breathe in the sounds of 40m for the first time last weekend and even managed to copy some Croatian DX during last week's contest. As Farhan said to do, I have spent the last few days enjoying the receiver and figuring out its quirks before moving on to the next step. 

The only "issue" I have noticed is that I still get some AM breakthrough despite tuning in the bandpass filter. The problem is very noticeable if I accidentally put my finger on the wires going to the AF gain pot. If I do that the AM station is the only thing I can hear. This makes me think the problem is after the bandpass filter and more investigation is needed. Maybe using coax on the control lines to shield it will help? Regardless I am impressed with how well the receiver sounds, the stability of the oscillator, and the effectiveness of the simple audio amp....  

Again thank you and Pete for your work on the podcast and for helping inspire countless homebrew radio operators! 

As a thanks for reading through this long email, I'll leave you with some photos of my build as a reward. 

73s,

 Derek N9TD

So Many Great Pictures, So Much Radio History

 

I make it a point to go back to Wes W7ZOI's web site every once in a while.  That is always a good idea. This time I found myself looking at the page that described Farhan's 2017 visit.  Wow, just look at the guys at that table. 

-- Wes W7ZOI.  The man who launched the solid state direct-conversion receiver revolution.  Author of SSDRA and EMRFD.  And so much more. 

-- Roger KA7EXM.  Son of Wes.  The guy who developed the receiver for the Ugly Weekender transmitter.  

-- Rick KK7B.   The guru of phasing type direct-conversion single signal receivers.  

-- Roy W7EL.  Father of EZNEC antenna modeling software. And the optimized QRP transceiver, with the diplexer that we are using (perhaps improperly) in our high school direct conversion receiver project. 

-- Jeff WA7MLH.  Builder of so many of the great projects in SSDRA.  Made me feel good about gear that looked a bit rough.  

-- Farhan VU2ESE.  Creator of the BITX20, the BITX 40 Module, the uBITX, the sBITX and so much more. 

Just scroll through the site.  You will see Rick there with his Classic 40 phasing receiver.  Roy with his  Optimized transceiver.  Roger with the Ugly Weekender transceiver. 

Finally, the morse key that Farhan gave to each of the participants.  Farhan gave me one of these too.  I will try to use it from the Dominican Republic on Straight Key Night. 

Check out the site: 

https://w7zoi.net/Farhan-visit.html

More Shortwave Listener Cards

Around this time every year I get an envelope from the W2 QSL bureau in New Jersey.  This year, the envelope contained two QSL cards from shortwave listeners. 

The Dutch listener heard my 12 meter SSB contact with Iceland.  The Russian SWL heard my 17 meter SSB contact with Japan.  

I think it is wonderful that we still have shortwave listeners who monitor the ham bands and send out QSL cards.  I will, of course, send cards back to them. 

Here are some cards from earlier (in some cases MUCH earlier): 

https://soldersmoke.blogspot.com/2023/11/some-short-wave-listener-qsl-cards.html

SolderSmoke Shack South -- with Mythbuster II and AN762 .1 kW Linear

This is the current operating table at HI7/N2CQR.   

The box up on top is my Mythbuster II -- like the original Mythbuster, but without the circuitry for 75 meters. Below it is the 15-10 I rig with dial from Pericles HI8P (SK). 

The shiny box with the heatsink is my new AN762 .1 kW linear from CCI. Most of this amp was assembled in Virginia, but I did the relay work and "socketry" here in the DR.  It seems to work fine.  I use it with the little box to its right which houses the Low pass filter board from a Ten-Tec Delta (Pete advised me to buy this back in October 2023). 

Out on the terrace in the upper right you can see the bottom of the 16 foot fishing pole that is holding up my 20-15 1/4 wave groundplane antenna.  I have already crossed the pond many times with this combination. 

KE5HPY's Altoids Direct-Conversion Receiver for 40 Meters

Click on the image for a much clearer view.

It is a thing of beauty.  You can see all four stages in there.  There is the Bandpass Filter in the upper left.  Below that is the VFO.  In the center you can see the SBL-1 mixer. Off to the right is the audio amplifier.  FB Chuck! 

Chuck KE5HPY writes: 

Allow me to add an endorsement of the joy and practicality of the DC receiver. Whether XTO, VFO or DDS, ring diode mixer, or Polykov, the DC IF concept is a real winner.  They really deliver wonderful audio and clarity that is very satisfying for homebrew builder.

Thought you might enjoy these photos of a 40 m receiver and built 10 or so years ago.  The design is straight out of EMRFD.  At that time, the Altoid tin craze was in full swing and this is one of several projects I stuffed in a tin.  This compact receiver has traveled on lots of camping and kayak trips where it delivered good DX reception using only a 30 foot piece of wire for antenna running back to the tent. It’s fun to hear intercontinental QSOs when you’re in the middle of nowhere. With my 40 m dipole attached at home, I think this little rig can hear anything my Icom hears.  

It’s great that you’re promoting this practical technology. Keep up the good work.