VE3BOF's Regens and DC Receivers

VE3BOF BENCH

Hi Bill:

This is Clark, VE3BOF, in Hensall, Ontario, Canada.

Hensall is located in southwestern Ontario, north of London and a 2  

hour drive west of Toronto.

Last Sunday night, 2017-10-01, I tuned in to 7277 kHz to listen to  

the BitX40 net. I heard you and 2 or 3 others.

Your signal was 5-7, perfectly readable.

The receiver I was using is a modified version of the WBR receiver.

It is still on the piece of chipboard that I mounted all the modules  

onto.  It's an excellent little regenerative receiver.

In the same state of incompleteness, is a modified version of the  

Easy Receiver (QRP Kits) direct-conversion receiver,

I use this receiver for the CW end of the 40M band.

Both receivers have been fitted with 10-turn pots for easy tuning,  

and also lcd frequency counters for displays.

I'm a former Motorola Communications tech, and used to maintain the  

radio systems of District 6 of the Ontario Provincial Police and our Ministry 

of Health emergency services radio system.

Being retired now, I have more time to check Soldersmoke every day  

and listen to your

conversations with Pete, N6QW.

Thank you for very interesting and worthwhile QRP information and  

programming.

Clark Forrest, VE3BOF

ANOTHER Nobel Prize Winner with THE KNACK

When I heard that the guys who ran the LIGO gravitation wave experiment won this year's Nobel Prize for physics, something told me that at least one of those involved in this historic detection of weak distant signals would have THE KNACK.  It did not take me long to confirm this.  Rainer Weiss (above) definitely has had the THE KNACK all his life. And what an interesting life it is.  Check it out:
http://www.sciencemag.org/news/2016/08/meet-college-dropout-who-invented-gravitational-wave-detector

Knackish excerpts: 

The family soon had to flee again, when U.K. Prime Minister Neville Chamberlain signed an accord ceding parts of Czechoslovakia to Germany. They heard the news on the night of 30 September 1938, while on vacation in the Tatra Mountains in Slovakia. As Chamberlain’s address blared from the hotel’s massive radio, 6-year-old Rainer stared in fascination at the glowing array of vacuum tubes inside the cabinet. The hotel emptied overnight as people fled to Prague.

As a teenager, Weiss developed two passions: classical music and electronics. Snapping up army surplus parts, he repaired radios out of his bedroom. He even made a deal with the local toughs: If they left him alone as he lugged radios to and from the subway, he’d fix theirs for free. “They would steal things and I would have to fix them,” he says. “It wasn’t a good deal.”

Weiss was drawn to tinkering partly as a reaction to his family’s cerebral atmosphere. “This is a German-refugee kid with very self-consciously cultured parents, and he’s rebelling against them by doing things with his hands,” Benjamin says. “But he’s surely not rejecting doing things with his head.”

He applied to MIT to study electrical engineering so that he could solve a problem in hi-fi—how to suppress the hiss made by the shellac records of the day. But electrical engineering courses disappointed him, as they focused more on power plants than on hi-fi. So Weiss switched to physics—the major that had, he says, the fewest requirements.

The Homebrew Receivers of F5LVG

I came across OM F5LVG's work in SPRAT.  He has a wonderful website -- it is in French, but Google Chrome translates is quite nicely.  

http://oernst.f5lvg.free.fr/index.html

From the site's introduction: 

This site is dedicated to the construction and understanding of radio receivers. If you have dreamed of hearing a radio station with a receiver that you have built yourself, this site is for you.  These are essentially direct conversion receivers and modern feedback detectors using only semiconductors, except for retrofitting. The described stations will accommodate amplitude modulation, single sideband (SSB) and telegraphy.

Besides these receivers several articles are devoted to LC oscillators. In particular, an extremely simple original stabilizing device is described.

Similarly, a simple frequency meter is described.

The joy of reception using a homebrew receiver is intense. May this site help you find this joy. Do not hesitate to join the amateur community.

TRGHS: I Can Hear the Roosters of Boa Vista

At the instigation of  Bob N7SUR I've been working on a simple, easy-to-reproduce Direct Conversion receiver for 40 meters. I'm building this for my nephew John Henry,  and I'm hoping this will be a circuit that others can use to break into the ELITE corp of successful ham receiver builders. Coincidentally Joh in Freiburg Germany is working on a very similar project -- we have been comparing notes. 

At first I used an FET detector described by Miguel PY2OHH.  It worked, but at night the AM detection of powerful shortwave broadcast stations drowned out the amateur signals.  So Joh and I started to explore detectors that would eliminate this problem.  I went with a version of one described in SPRAT by F5LVG ( "The RX-20 Receiver"- see below).  Very simple:  A transformer to two back-to-back diodes with a 1K pot to balance the signal from the VFO.  OM Olivier used a very, very cool transformer: he took two small, molded chokes and simply glued them together!  22uH choke as the primary, 100uH choke as the secondary. I went with one of the toroidal transformers that Farhan left me when he visited in May. 

 I'm using a varactor-controlled ceramic resonator VXO  (no Si5351 in this one!) and a non-IC AF amp designed for use with ear buds (the world is awash in ear buds).  It is a "singly balanced" design with the incoming RF signal being the one "balanced out" in the detector.  

Last night the receiver passed the AM breakthrough test.  The SW broadcast monsters were balanced out and kept at bay. 

This morning the receiver passed The Boa Vista Rooster Detection Test.   I fired up the receiver and heard an operator speaking Spanish with a Brazilian accent.   When I heard the rooster crowing in the background I knew it was Helio PV8AL from Boa Vista Brazil.  TRGHS -- this little receiver is a winner.  

I'll try to post a schematic soon.  

And hey -- look at what wonderful IBEW (International Brotherhood of Electronic Wizards) project this is:   Instigation and inspiration from Oregon.  Some design ideas from Brazil.  A French detector circuit described in a British QRP magazine. A transformer from India.   A collaborator in Germany.    And finally, the rooster of Boa Vista.    

Let's not forget Wes Hayward W7ZOI for bringing back (in 1968!) the neglected Direct Conversion idea.

Two new bands for US Amateurs

630 meters 1 October 2017

Steve VE7SL reminded us via his blog that US radio amateurs now have the use of two new radio frequency bands: the 2200 meter band and the 630 meter band.  As always, Pete N6QW was way ahead of the game and is already working on a full-size 6 element quad for 2200.  Good going Pete!  Please send pictures (we may need a satellite photo to get the whole antenna in the shot).  

As Steve points out there is already a lot of activity on the new bands -- the attached pictures are snaps of just ten minutes of WSPR activity this morning.   

I'm especially intrigued by 630 meters -- it is so close to our beloved 455 kc IF frequency.  Will some intrepid ham take advantage of this fact?  Seems like some peaking and tweaking could do the trick...  

Check our Steve's blog post: http://ve7sl.blogspot.com/2017/09/getting-started-on-new-lf-and-mf-bands.html

2200 meters 1 October 2017

NPR: Hams Help in Puerto Rico

I got into my car to drive home yesterday.  As soon as I turned the radio on, I heard this.  TRGHS. FB OM.  Listen.  4 minutes. 

http://www.npr.org/2017/09/29/554600989/amateur-radio-operators-stepped-in-to-help-communications-with-puerto-rico

More on GM3OXX

Sunset at Luce Bay Scotland, 3cm GM3DXJ, GM3OXX and GM8HEY dishes being set up. Photo GM8HEY (GM4JJJ). 322 km QSO to Wales. 10mW GUNNS WBFM.

Bill,

Thanks again.

I recall when George met up with the team from Wales in a car park in the Scottish highlands , they had also built 3cm gear and he found by direct comparison that their 3cm gear was more sensitive than his. He went straight home and redesigned and rebuilt his receiver. That gear then went on to break the World distance record on 3cm on a superrefraction path from Portpatrick to Cornwall with 10 mW WBFM. Smashing a record that the USA had held for 16 years from mountop to mountain top.

George was ambitious, he wanted that UK, EU and World distance record, he wanted to show the RSGB that Scottish hams could get the 3 countries and 20 counties award on 3cm. We  (G8BKE, GM3DXJ, myself and George) did it by travelling round Scotland in my Mini Clubman Estate with dishes and tripods and 3 hams packed in to one car, at the same time fitting in the EU distance record from Luce Bay in Wigtownshire to St David's Head in SW Wales at 322 km just to show them how.

No VHF Talkback, only a phone call from a telephone box earlier in the day to our Welsh counterparts to say we would be there about 6pm and to tune the 3cm band for us. Frequency uncertainty was in the 10's of MHz.  We arrived at the beach, set up 3 dishes, put on our transmitter test tones and then went back to receive, George asked us to make sure we had our test tones -off-  as his receiver was overloaded, it was the Barry Radio Guys he was hearing, they were so strong. Didn't matter where we pointed the dishes, we were in the sea level duct. Open waveguide still full quieting.

George's words audible on the remote tape recording made in Wales, " You can pack up your gear now lads, that's the European Record!"

Happy Days!

-- David GM4JJJ