Listen to Latest SolderSmoke Podcast

Friday, January 31, 2020

WA2EUJ's NXP RF Power Amplifier Design Challenge Entry -- Won First Place Prize!



Congratulations to Jim WA2EUJ.   First Place the NXP Design Challenge. 

You can buy the board here: 

https://sites.google.com/site/rfpowertools/home/nxp-mrf-101

Thanks to Pete Eaton WB9FLW for alerting us to this. 

Thursday, January 30, 2020

Mountain Topping in Indonesia -- Very Cool Video



OM Kenji has an awesome video about a mountain topping trip that took place in Indonesia just yesterday.  Very nice.  

I like the use of the neodymium magnets to attach the paddles to the rig.  I may try that with my homebrew straight key and the Samana-uBITX. Or I may have to get a keyer and learn (finally!) to use paddles.  (But simplicity is a virtue and there is nothing more simple than a straight key.) 

Kenji is obviously an amazing cook, even in the field.  I like the coffee-making technique. 

Check out more of his videos (and subscribe) at his YouTube Channel page: 

https://www.youtube.com/channel/UCpfn1viFoqVmWk6x891nKaQ   

Thanks Kenji! 



Wednesday, January 29, 2020

DK7IH's New HOMEBREW Transceiver Raises the Bar for All of Us


And that, my friends, is a HOMEBREW transceiver.  Wow, amazingly well done.  After I showed this to Pete N6QW (no slouch in the homebrew packaging department), in frustration with his self-perceived shortcomings he threatened to give up on homebrewing and to throw away all his rigs. Don't do it Pete!   

Peter Rachow, DK7IH has carefully documented his project through as series of blog posts: 
Here is Part 1: 

Part 9 deals with mechanical construction, packaging and what George Dobbs used to call "socketry."

Thank you Peter for taking the time to share your project with all of us.  It is really inspirational. 




Tuesday, January 28, 2020

Junk Box Ethics -- I Plead Guilty! (video)



I cringed when, at about the 32 minute mark,  during a discussion of the moral necessity of preserving old gear, Michael appeared on the screen with a Heathkit Q multiplier sitting right there next to him.  It was as if he was talking about me.  I felt as if I had been hauled into Ham Radio Court, Judge Michael Murphy presiding. 


I have already REPEATEDLY admitted to sacrificing MULTIPLE Q MULTIPLIERS.  But I did it for good reasons:  

1)  I have some objections to use of regeneration, especially in superhet receivers.  After all, Armstrong created the superhet in part to free us from the tyranny of regeneration (that he had also invented).  

2)  This is a case where the parts ARE greater than the sum.  Specifically that variable cap WITH reduction drive.  And that perfectly sized metal box. Those capacitors are currently in service in at least two of my homebrew SSB transmitters. And as I look around the shack, I see one of those boxes housing an Si5351 VFO, and another holding the dual-digital frequency displays for my DX-100/HQ-100 AM station.    

3)  Mike notes that these Q-multipliers are being sold for TWO DOLLARS at hamfests.  At prices like this, temptation is just too strong. 

So I plead guilty, your honor.  But I ask the court to consider the circumstances under which I dismantled this obsolete gear, and the good uses that I made of the parts that I obtained.  Also, I'd like to make note of the fact that I salvaged from a junk pile a Heath VF-1 (I completely rebuilt it) AND I restored to usefulness a Heath DX-40 -- both these devices appeared in the WU2D video.  Finally, if anyone really needs the remaining parts from the now deceased QF-1s, I'd be willing to donate them (in an effort to redeem myself). 

Thanks Mike!  

Monday, January 27, 2020

How to Generate an AM Signal (and DSB!) in LTSpice



Pretty cool and very useful.   You can also do this by using the Modulator symbol, but I found this technique easier and more straightforward. 

But be sure to watch all the way to the end of the video.  Early on, he forgets the step that causes the carrier to stay in the simulation, but then shows how to correct this.  In the process we learn how to create a DSB (suppressed carrier)  signal in LTSpice. 

Sunday, January 26, 2020

Lebanon's First Radio Website



I found this site through Paul VK3HN.  He took the AM detector circuit for his AM receiver from one these Lebanese homebrew radios.  

There is some really great information on this wonderful website.  It has been online for some 20 years -- I wish I had found it earlier.  The author shares his Knack story -- this is a wonderful example of the International Brotherhood of Electronic Wizards (IBEW). 

http://www.midcenturyradios.com/index.html

And he has very cool schematics, really well done.  Click on image to enlarge: 


Saturday, January 25, 2020

Wild Woody WARC Keys


From the NAQCC newsletter: "The key is Dave's own unique invention called the WILD WOODY WARC KEY, and each key is consecutively serial numbered. (My key is number 476). WILD WOODY WARC KEYs have a place of honor in the ARRL Headquarters, and in the offices of Kewnwood, Icom and other such places. Dave, as some of you may know writes a monthy column for CQ Magazine and is the author of several books on keys, QRP operation and other subjects. The WILD WOODY WARC KEY is pictured below. Ingenous simplicity -- a true work of wonder. Thank you Dave."

I post this for several reasons.  

1) A friend recently complained that telegraph keys are getting expensive.  "Ha!" I said.  This proves me right.   Clothes pins are not expensive. 

2) I think we should make more use of clothes pins in ham radio.  They were used in my 20/15 meter dipole in the Dominican Republic. 

3) I worked K4TWJ several times -- twice from the Dominican Republic, and once from Virginia using a homebrew transceiver that he had inspired.  He was pleased.  It was cool. 

4) As a little kid, I liked Woody the Woodpecker. 

4) On Thursday morning my wife and I saw a Pileated Woodpecker (just like Woody!) in our neighborhood.  TRGHS. 




Friday, January 24, 2020

Mr. Carlson's Lab Attacked by Dangerous Canadian Snow Static! (Video)



Even when describing something as simple and basic as snow, Mr. Carlson is electronically awesome.   This video made me realize that in the event of an EMP, his will probably be the only lab to survive.

The SolderSmoke Daily News took up the topic of snow static back in 2011.  Be sure to read the comments, especially the one from KC7IT about the QUARTER INCH ARCS that woke him up in the dorm at MIT.  Check it out: 

https://soldersmoke.blogspot.com/2011/10/snow-static.html#comment-form

I've got to get one of Mr. Carlson's 2020 calendars! 

  

Saturday, January 18, 2020

The End Fed Half Wave Antenna and EFHW Tuners



In the SPRAT 179 (Summer 2019) article describing their Peregrino (Pilgrim) transceiver,  Joan EA3FXF and Eduardo EA3GHS recommend the use of an End Fed Half Wave (EFHW) antenna. Their circuit incorporates an EFHW tuner and an SWR indicator.  As I planned my trip to the Dominican Republic with a uBITX, I had this antenna system idea in mind.  I was attracted by the possibility of avoiding having to carry coax with me.  And it seemed that an EFHW antenna would be easier to get up in the air than a coax-fed dipole. 

When searching for schematics for EFHW tuners I came across the QRPguys tuner kits.   

https://qrpguys.com/end-fed-half-wave-sota-antenna-tuner

This looked like just what I needed, so I ordered one.  But I placed my order kind of late, and I started to worry that I might not get the tuner kit in time.  So I decided to homebrew my own (just in case!) 



As it turned out, QRPguys got the kit to me in plenty of time. It went together very quickly and is a really useful piece of gear.  My homebrew version works fine, but I prefer the QRPguys device. 

You can check out the manual here: 

https://qrpguys.com/wp-content/uploads/2019/09/efhw_40m_tuner_assy_090119.pdf

The circuits are interesting.  The EFHW antennas present an impedance not of 50-70 ohms, but of 3000-5000 ohms.   The Peregrino and the the QRPguys circuits use a matching transformer to change the high impedance to 50 ohms.  In both circuits polivaricon capacitors are used to tune for resonance. The QRPguys circuit uses an N7VE LED absorption bridge -- I found it very satisfying to put the circuit into "tune" mode and then just adjust the capacitor until the LED went out.  That means the antenna system is presenting 50 ohms to the transmitter. 

SOTA beams has a good explanation of the EFHW antenna here: http://sotabeams.co.uk/efhw/
I did use a counterpoise. 




Friday, January 17, 2020

Thursday, January 16, 2020

Mike WU2D on QSO Today with Eric Guth 4Z1UG


Eric Guth has a great interview with homebrew and boatanchor guru Mike WU2D.  

Listen here: 

https://www.qsotoday.com/podcasts/WU2D

Wow: "My receiver was from a Sherman tank." 

His story about getting in trouble after "borrowing" his friend's callsign was really great. 

I also liked his wise comment about how anyone who homebrews simple gear will collect some "wallpaper" from official observers and the FCC.   Mike is right:  we shouldn't get too concerned about minor transgressions. If we do, we run the risk of becoming so careful, cautious, and fearful that we never BUILD anything.  

There is a wonderful discussion of the Paraset. 

Mike coins a term that we might want to add to the SolderSmoke lexicon:  RetroQRP.  (Over to you Steve Silverman.  Your call OM.) 

Wednesday, January 15, 2020

Notes From the Dominican Republic on possible uBITX mods


It was really great to have the multiband and CW/SSB capabilities of the uBITX with me in the Dominican Republic.  And even with my large wooden box, the rig and all its accouterments fit into my carry on baggage (and there were no problems with airport security). (In the picture above you can see the cloth case that held the whole station, including the antenna.)  

As I used the rig, I thought about possible mods for future operations.   Here are some ideas: 

-- Filter for CW?  Definitely.  Farhan suggested switching in a more narrow 12 MHz IF filter for CW operations, but that seems like a bit too much work.  I am going to try to use an audio frequency filter.  I've ordered the active CW filter from QRPguys.  I've long been intrigued by these kinds of filters, but they didn't seem very wirthwhile with a DC receiver.  With a superhet like the uBITX they make a whole lot more sense. 

-- Sidetone volume control.   Need it, especially with fellow vacationers trying to sleep nearby.  Should be easy -- just a pot on the side-tone line.

-- Low impedance mono headphones.  Need them.  

-- An LED light for logging.  Would help. 

-- Switch to turn off the 16X2 display to save power?  I thought about this but I checked after we got back and the whole display pulls only about 20 ma.   So it probably isn't worth it to put in a switch. 

-- Internal protective cover for the uBITX board.    I used the extra space in my big wooden box to store the key, the mic, the battery, the tuner, etc.    They all bounce around a bit and could damage the uBITX board.  So I will try to build in some internal physical shielding, perhaps from a BITX plastic box. 

-- Brass contacts for my homebrew CW key.   I think brass is better than the copper foil I am currently using.  I already did this with some brass bolts from the local hardware store.  Mush improved.  Pounding brass is better than pounding copper tape. 

-- I installed an additional stage of microphone amplification but I have this stage running even on receive.  But I checked and the amount of current pulled by this stag is so small that it is not even worth changing the power supply line. 

--  Reduce output to below 5 watts on CW.   To make the rig "QRP Compliant."  



In the pictures you can also see my homebrew straight key, the QRPguys EFHW tuner, my mic (the original SolderSmoke podcast mic!), the 3 amp-hour LiPo battery, the additional stage of mic amplification.   The little relay that you see just above the mic amp allows for the keying of an external amplifier. 



Tuesday, January 14, 2020

Aeronautical Mobile Contact from the Dominican Republic

767
On the morning of January 9, 2020, I was up early, sitting alone out in my open-air tropical hamshack on Bahia Rincon on the Samana peninsula of the Dominican Republic.   I had been looking at the stars. As the sky brightened I was listening to band noise from a still-dead 20 meter band on my uBITX.  

Skies were partly cloudy.  The Big Dipper hung upside down in front of me.  I had also seen Corvus, Scorpio, Andromeda, and Leo.  There were a few meteors and one bright satellite.  

But 20 was quiet... until, suddenly,  BOOM! A very loud and clear SSB signal came through.  It was KX4WE/Aeronautical Mobile.  Mike was in a 767.  I called him and he came back right away, giving me a 57 report. He gave his position as 170 miles Northwest of San Juan, Puerto Rico.  He was heading to Port-o-Spain, Trinidad from Miami.  We had a quick QSO -- it reminded me a lot of my contacts with the MIR space station from Santo Domingo in the mid-1990s.  Suddenly Mike's signal dropped very significantly.  I figured that he had moved further south and was no longer line-of-site with me. I had some hills to my south and they were now attenuating Mike's signal.  I could hear him working M0NKL.  We were Mike's only two contacts on 20. 

I realized later that had I looked up, I might have seen the lights of the plane.  Below is the track of the aircraft.  He was at 35,000 feet when he passed over the DR. 



This contact was a lot of fun. Thanks Mike! 

Monday, January 13, 2020

Contacts from the Dominican Republic


Below I have my log from the Dominican Republic.  A few noteworthy contacts highlighted in yellow.  The first contact was actually on 30 meters,  My guess is that the 20 meter EFHW and the counterpoise got close to half wave on 30. 

AE7KI's was a famiiar voice. Terry transmits from Tennessee but his voice is from down under.  I recognized him before I heard the callsign.  

F6HKA was a familiar call.  I checked -- he was a Straight Key Night contact from one year ago.  Great to meet up with Bert again. 

The Aeronautical Mobile contact was icing on the cake.  More on this tomorrow...

Thanks to all who contacted me or tried. 


In the Dominican Republic 30 December 2019 – 11 Jan 2020

4Jan2020 
30 meter CW HK1ANP Fred.  I was in Bavaro.  30 meters on an 20 meter EFHW!

All subsequent DR contacts on 20 meters from Samana near Las Galeras

6Jan2020
0922 CW EW1I Alex in Belarus.
0959 SSB KG4ZEC. A net on 14.300
1657 CW KB3WAV Md
1701 SSB AE7KI Terry – old friend from Tennessee and Australia.

7 Jan 2020
0917 CW F6HKA Bert near Limoges 14.050 SKCC 60693
1500 CW KN4ZQ Dave in Palmyra Va. Me 599
1523 NO CONTACT but close,  CW KC2OHL
1800 CW KC5F Steve – he answered my  CQ   NC SKCC 21092T

8 Jan
CW N3JB John in Va. Me 599
CW W9YXX Bob in Ind. Me 569
1749 CW W8TK Tom in Tuscon Az.

9 Jan
0700 SSB KX4WC/AM Me 57 767 170 miles NW of San Juan
0840 SSB KI5PZE Miguel, Lake City Fla. In Spanish.
0908 SSB W1FDY Jack in SE Va. Me 58 



The point of the Pen shows where we were in Samana. Bavaro is on the Eastern tip if the island.

Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column