Direct Conversion (videos)

Here are a couple of videos from 2017 (never posted before).  I built a little 40 meter Direct Conversion receiver for my nephew John Henry.   

Whenever we work on circuitry like this, we should be be grateful for Wes Hayward W7ZOI who, in a 1968 QST article, reminded us of this important but until-then forgotten technique. 

More information on this project appears in these links: 

https://soldersmoke.blogspot.com/2017/10/a-direct-conversion-iphone.html

https://soldersmoke.blogspot.com/2017/11/iphone-direct-conversion-receiver-with.html

Minimalist Masochism at Solar Minima -- But More Contacts with the ET-2

Dylan Thoams

  "Rage, rage against the dying of the light" 

I thought of that line from Dylan Thomas's poem when I read on G3XBM's web site that we are kind of at the very bottom of the solar cycle.  Roger wrote on 22 October: "Solar flux is 64 and the SSN 0. A=5 and K=0. As far as I am aware this is the lowest solar flux this solar minimum."   

I also thought of this as I pounded brass (Indian brass!) in an effort to make a few more contacts with my ET-2 two transistor rig.  Obviously venturing forth on 40 meters with just TWO transistors (one for transmit and one for receive) and crystal control AT SOLAR MINIMA is not for the faint of heart.  It is almost a Dylan-esque act of defiance. 

I have had to resort to please for help on the DX Summit, the SolderSmoke blog and the SKCC Schedule page.  Fortunately for me, the brotherhood has sprung to my support.  

W1PID (who gave me contact #3) also gave me contact #4 on 21 October. 

W4KAC in Hickory NC was contact #5.  This was on 22 October.  This was the only marginal contact so far.  He was running 5 W into an end fed half wave. 

Yesterday was a big day for the ET-2. I had two solid contacts: 

#6 was N2VGA in New York UPDATE:  Larry N2VGA confirmed by e-mail that this was a "random" contact -- not the result of my on-line pleas for assistance.  He just heard my CQ and responded.  FB.  

#7 was K4CML in Newport News, Va.  He switched to QRP himself at 2.5 watts for a nice 2X QRP contact. 

Looking at my Rigol 'scope, I now think I'm putting out about 150 milliwatts.  Not bad for a single J310.  I may have to invest in a heat sink.

40 seems most cooperative in the morning (around 0930 local) and again in the afternoon (around 1630 local). 

Thanks to all who have helped.  I will try to make a few more. 

Radio Telescope Homebrewed from Cake Pans and Chicken Wire

 

https://altaonline.com/the-low-tech-search-for-signs-of-intelligent-life/?utm_source=pocket-newtab

Revamped SolderSmoke YouTube Channel -- Please Subscribe

I did some work on the SolderSmoke YouTube Channel: 

https://www.youtube.com/user/M0HBR

And I added a bunch of videos that had somehow ended up in different channels. 

Please visit, watch some of the videos and subscribe.  From now on I will put all of the videos in this channel.   

Thanks!  73  Bill 

Farhan Visits Northern Virginia and SolderSmoke HQ

 

Our good friend Farhan came to Northern Virginia last week for the 50th Anniversary Symposium of AMSAT.   We were really delighted that he also came to SolderSmoke HQ.  Elisa and I gave him a lightning tour of Washington DC (including a quick visit to The Air and Space museum) and then we headed back to the shack from some radio work. 

In the picture above you can see my BITX-20 (that Farhan designed) off his right shoulder.  Off his left shoulder you sits my ET-2 rig.  I really wanted to show Farhan how well the N0WVA regen performs -- he was impressed, especially when we started listening to SSB contacts. It was really amazing that we were doing this with just one J-310 FET.  This was great fun.  Farhan tells me that he will soon take up the "two transistor challenge."

When he was here in 2017, I tried to demonstrate my version of Rick Campbell's R2 Direct Conversion receiver.  Unfortunately, when I tried to show off the "single signal" capability that is the whole purpose for this receiver, it was NOT producing a single signal output -- you could hear the signal on both sides of zero beat.   One of the small AF chokes I had used had gone open, knocking our one of the two DC receivers.  This time I had the problem fixed and single signal reception was successfully demonstrated.  

Farhan brought me two pieces of test gear that I have needed for a long time:  A step attenuator and a two tone generator.  Paired with his Antuino, these devices will bring about a big increase in capability on my bench. 

It was really great to have Farhan in the shack.  We had a great time talking about ham radio and homebrewing.  Elisa and I both really enjoyed hearing from Farhan about his travels and about his life in India.  We are all really lucky to be in the same hobby as Ashhar Farhan. Thanks for the visit Farhan.

Here is a quick video of Farhan tuning the BITX 20.  

QSO #3 with the ET-2 Minimalist Transceiver

 

The Radio Gods were clearly supporting me on 16 October 2019.  I had sent out a plea for people to listen for the 80 mW CQ from my ET-2 rig.   I had specified 0930 Eastern as the time.  Little did I know that there would be a contest at that hour (on a Wednesday morning!) on 40 meter CW.  There was no chance of my signals getting through.  I leaned that the contest would be over at 1000 hours, so I waited and called CQ again at that hour.  Jim W1PID had guessed that I would do that.  I immediately recognized his call -- he was often at the other end of Michael Rainey's most daring low-power adventures.  He was a participant in the famous Rexpeditions, including a coastal effort to send Michael's voice-powered CW signal across the Atlantic.  His normal operating habitat is in the field.  We had a wonderful QSO.  He told me I peaked at S-6.  

I have worked W1PID on at least two Straight Key Nights and this blog has had many postings about his long-standing involvement in QRP. 

Thanks a lot Jim! 

 

Please Listen for My 80 Milliwatt CQ Tomorrow, Wednesday 16 Octoberr

I will be calling CQ from Northern Virginia starting at 1330Z (0930 Eastern) on Wednesday 16 October 2019 on 7038.6 kHz with my ET-2 QRPpp rig.   I have made two contacts so far -- both contacts were at a range of about 300 miles.      I'd like to be able to make at least one per day.   If you are within range please listen for my CQ tomorrow and give me a call.  

Thanks and 73  Bill N2CQR

The First Sunspots of Cycle 25 -- Explained by Space Weather Woman (Video)

Dr. Tamitha Skov explains how Cycle 25 has begun while Cycle 24 is not quite finished. 
She has a very clear way of presenting the space weather.  Very useful. 

YouTube site: https://www.youtube.com/channel/UCkXjdDQ-db0xz8f4PKgKsag

More on the ET-2 : Better Pictures and More Circuit Description. Some Thoughts on Simplicity

 

So yesterday I made my first contact using my ET-2 rig.   Last night I got an e-mail from Gary, the fellow at the other end of that contact: 

Evening Bill, N2CQR….Yes I did learn about you from the spot on the DX Summit cluster. I tuned to the freq to see if I could even hear your 80 mW and you were a good real 569 when calling CQ.  You built up to a real 589 on the later transmissions. I did not have either of the two pre-amp positions on in the ICOM 756 Pro II. There was not any QRM on the freq either. Your spot indicating the 80 mW is what really got my attention.

My antenna is a 2 element yagi at about 115 ft and it really works great for me.

Thanks for the picture of the great little transmitter. Glad to be your first DX QSO with it. Hi Hi  Maybe again soon.  My pleasure to work you.

73, Gary, K4MQG

Fort Mill, SC

Farhan commented on yesterday's post, saying that it was hard to tell (from my pictures) where he rig started and ended.  He was right.  So this morning I have tried to clean up my bench a bit -- I hope these pictures are better.  

Above you see the whole rig.  The transmitter board is right next to the key that Farhan gave me.  You can see the 7040 crystal.  A C-Clamp holds to the bench the piece of scrap plywood that serves as the base for this rig.  Next to the C-Clamp you see the TR switch -- the just switches the antenna -- both transmitter and receiver are powered at all times.  I can hear the transmit signal in the headphones and this serves as my sidetone. 

Here is a close-up of the transmitter with the schematic below: 

 

The transmitter is VERY simple.  Nine parts, including the low-pass filter.  You can barely see the J310 FET to the right of the crystal. 

Here is the receiver:

I really like N0WVA's regen.  The green diode in the source circuit is the key.  This one does not squeal when you go into excessive regeneration (when you think about it, regens should NOT squeal at audio frequencies -- but most do).  Also, the green diode dims a bit when you are at the right amount of regeneration.  In the picture you can look down the tube of the variometer that Pericles HI8P gave me many years ago.  The big variable cap is from the junk box -- I think it may be from a Johnson Viking transmitter.  Note the long shaft with the insulating connector -- this is to reduce the hand capacity effect.  On the right you see a smaller cap with just one vane -- this is my fine tuning control --- with the smaller cap at mid range, I would just set the big capacitor to put the receiver at 7040 -- with the smaller cap I could tune +/- 12 kc.  I also used an insulating shaft on the smaller cap -- the connector for this one is from an old 1930s era regen that I picked up at the Kempton Part rally in London.

Instead of the audio transformer and Radio Shack headphones, I just used some old DLR-1 WWII Headphones.   They are very sensitive and work well. 

Lots of soul in this new machine:  The variometer from Pericles.   The WWII headphones.  The 1930s era shaft connector.  The circuit idea from the Autumn 2001 SPRAT.  Farhan's key. 

I recently read on Hack-a-Day of a new FPGA chip that has on it 35 BILLION transistors. I'm sure that thing can produce some fascinating results, but can anyone really understand it, or feel that they really BUILT something that has that kind of chip at its center?   On the other hand, I did rely on a lot of modern digi technology in this project:  The Reverse Beacon Network reported back that my unanswered CQs were in fact getting out (one as far as Kansas to K9PA).  And in the end I had to ask -- via the DX Summit Spotting cluster -- for someone to listen for me.   So I can't go full Luddite here.  And I wouldn't want to have to use a rig this simple every day.  No way.  It is just too hard to use. But there is a beauty and a challenge in simplicity.  There is some virtue in using just two transistors instead of 35 billion. 

Thanks to N0WVA, W2UW,  VU2ESE, HI8P, K4MQG, The G-QRP club and their inspirational journal SPRAT, the RBN and the DX Summit. 

Success with my ET-2 --TWO TRANSISTOR RIG

 

In my effort to replicate the ET-1 rig of Glen Yingling W2UW, I had a hard time getting the receiver to work well with the single FET being switched between receiver and transmitter, so I retreated a bit and went with individual FETs for the TX and the RX.  This doubled the transistor count -- to TWO.  So it is an ET-2.

I also boosted the power to 80 milliwatts by putting 12 V on the transmitter.  The receiver was running off the 9V battery you can see in the left in the picture. 

Here is the story of the contact: 

To K4MQG from N2CQR:

Gary: Wow thanks for the QSO today.  I was using 80 mW transmitter that consists of just 8 parts!  The receiver was a regen using one single transistor.  So one transistor on transmit and one transistor on receive.  And it reached South Carolina.

I was about to give up hope.  I had been calling CQ for days.  Then I was talking to Rob VE4GV on 20SSB.  Rob suggested that I "spot myself" on one of the DX clusters.  So I did (see below).  Obviously you saw my spot and a minute or so later, SUCCESS!   I'm really pleased.

Attached is a picture of the rig.  The transmitter is around the crystal and the blue pot on the right.  The headphones are from WWII.  The receiver was powered by the 9V battery.  The regen uses a variometer given to me by a friend in the Dominican Republic in 1992.  The main tuning dial is connected to the cap by an adapter from a 1930s-era regen.  Antenna was a 40 meter dipole at about 25 feet.  Obviously your 3 elements a 115 feet were doing the heavy lifting.

Thanks again Gary!

And thanks to Rob for the suggestion on the spotting.

73  Bill N2CQR

The BGCD: A Regenerodyne Receiver built on Pencil, Candy, and Tea Tins. Circuit from 1937 QST

David Newkirk recently put up a nice website on ham radio.   The page below provides details on the amazing creation pictured above:  The BGCD:   "The Byron Goodman -- Clinton DeSoto Regenerodyne." It is a beautiful piece of work, made more beautiful by the metal containers used in construction: pencil, candy and tea tins.  The circuit is based on a 1937 QST article. 

David's site reminded me of the wonderful writing of his father, Rod Newkirk of "How's DX" fame.   More on him in due course.

More on the BGCD here:

http://dpnwritings.nfshost.com/ej/pictures/pictures1.htm?fbclid=IwAR2-lmJ8E1kEBT_jsB3Q8UnPaN0vc472dP783ifABK7eSxgpe5M1Pl0N77g

Very Useful: Copper Tape with Conductive Adhesive

This copper tape is really useful, especially when doing "free style" homebrew.  At first I didn't even realize the adhesive is conductive.  This tape is great for creating a common ground among several printed circuit boards, especially when you are using a wood board as the base.  You can solder to it very easily.  You could even use it (with a wood or plastic base) in lieu of a copper clad board. Lots of possible applications for homebrewers. This stuff deserves a place on the workbench shelf right next to the Gorilla Tape and the Crazy Glue.   I'm using it in my Single Transistor Rig project. 

You can get it from Amazon -- there are many varieties and vendors.  This one is similar to the one I am using.  

https://www.amazon.com/dp/B01I1XNY1E?aaxitk=I9X2Na8Gu23M3nrhlpSzYw&pd_rd_i=B01I1XNY1E&pf_rd_p=44fc3e0f-4b9e-4ed8-b33b-363a7257163d&hsa_cr_id=3252618550401&sb-ci-n=asinImage&sb-ci-v=https%3A%2F%2Fm.media-amazon.com%2Fimages%2FI%2F71sJrx27%2B-L.jpg&sb-ci-a=B01I1XNY1E