Pete Juliano's Bilateral Rigs (with videos)

 

Hi Bill,

 

I was finally getting around to reading one of the recent SPRAT’s and saw a photo of your magnificent BITX17. Congratulations! A tip of the hat to Farhan for that very excellent design and it truly is a design that has traveled the world and made a radio available to many who otherwise would not be on the air.

 

It is a very robust design as I scratch built one in 2005 (or maybe 2006) and just for fun socketed every transistor so I could try various devices. I even had a bag of 2N706’s dating back to the late 1960’s. They all worked except for the carrier oscillator where I just couldn’t get enough swing in the oscillator to correctly place the CIO on the filter slope. That I attribute to the junction capacitance of the 2N706. By far the lowly 2N3904 that I bought for 4 cents each worked the best. Back when I built this I was W6JFR. Adding the EI9GQ frequency stabilizer really added a nice touch to the radio.

 

I should also tell you that when I built the radio my intent was to uses a piece of single sided copper vector board for the main chassis. It was the weekend and I didn’t realize the piece I had was not  big enough for the project. So I took a piece of standard perf board and overlaid that on top of a piece of single sided copper PC board –AND hand drilled all of the holes – I went blind, cross-eyed and had a terrible hangover after consuming 6 beers in a short time span! See the photos below.

 

BTW I also built a 17M SSB transceiver using the bilateral amp stage from G4GXO as appeared in the SPRAT 128. That used a 4.9152 MHz IF and a 23 MHz Super VXO. In the case of the VXO I used 11.52 MHz crystals in the VXO and used a diode doubler to put the LO at 23 MHz. With the doubler –you get the bonus of 2X the frequency shift of the Super VXO. I also had made a custom set of crystals and used a small relay to switch those into the circuit and that essentially gave me almost the full SSB Band coverage. You can see that here

 

http://www.jessystems.com/morexcvrs.html

 

Also I have been using a simple bilateral stage consisting of a 2N3906 and 2N3904 and the results have been amazing. The latest work is a follow on to my shirt pocket transceiver and uses SMD components. See attached.

 

Here are some  videos of the latest –which is now a two bander 40 and 20M. (Originally it was 75 and 40M)

https://www.youtube.com/watch?v=0UlBX7aznnM&list=UU4_ft4-oTdCMlWlL4XXHScg and https://www.youtube.com/watch?v=Wa5WiUZ9KoY

 

Have fun – this is such a wonderful hobby!

 

73’s

Pete N6QW
 

 

 

 

 

 

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Clocks, CRTs, HV supplies: Eric has The Knack!

Nice interview by Jeri Ellsworth.  This fellow definitely seems to have the Knack.  At the end of the video he shows a high voltage supply that he is WEARING AROUND HIS NECK! 

Here's Eric's site: http://tubetime.us/


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A Worthy Cause: Help Save the ISEE-3 Spacecraft!

http://www.rockethub.com/projects/42228-isee-3-reboot-project-by-space-college-skycorp-and-spaceref

Here is an excerpt from the above website:


Our plan is simple: we intend to contact the ISEE-3 (International Sun-Earth Explorer) spacecraft, command it to fire its engine and enter an orbit near Earth, and then resume its original mission - a mission it began in 1978. ISEE-3 was rechristened as the International Comet Explorer (ICE). If we are successful it may also still be able to chase yet another comet.

Working in collaboration with NASA we have assembled a team of engineers, programmers, and scientists - and have a large radio telescope fully capable of contacting ISEE-3.  If we are successful we intend to facilitate the sharing and interpretation of all of the new data ISEE-3 sends back via crowd sourcing.

Time is short. And this project is not without significant risks.  We need your financial help. ISEE-3 must be contacted in the next month or so and it must complete its orbit change maneuvers no later than mid-June 2014. There is excitement ahead as well: part of the maneuvers will include a flyby of the Moon at an altitude of less than 50 km.

Our team members at Morehead State University, working with AMSAT-DL in Germany, have already detected the carrier signals from both of ISEE-3's transmitters.  When the time comes, we will be using the large dish at Morehead State University to contact the spacecraft and give it commands.
Thanks to Dave, WA8JNM, for the heads up on this. 
 
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AA1TJ Crosses the Pond with 10 milliwatts

From a Facebook Post by Mike, AA1TJ:

Made 7 contacts with this tiny transceiver on 20m CW today with an RF output power of 10milliWatts. Five were stations in Georgia (GA QSO Party). The 6th was a regular QSO with a guy in Mississippi.
I answered a DX station calling CQ at 2230Z. Hearing nothing in response, I sent my call sign a half-dozen times anyway. More silence. As I was reaching for the knob to QSY he suddenly returned my call! ...Carlos, CT1BQH northeast of Lisbon, Portugal (that's him in the second photo). I was only 329 on his end but we kept it going for three minutes!

FYI: the transmitter (top circuit board) begins with a 3.58MHz ceramic resonator VXO (a 2N706 from the early 60's). That drives a push-push frequency doubler built around another 1960's-vintage, 2N2644 (obsolete stock from atop Mt. Mansfield, kindly given to me by Rich at Vermont Public Television). On receive, the 7MHz energy is routed via a DPDT relay (the orange rectangle) to the sub-harmonic (Polyakov) mixer located on the lower board. One stage of AF amplification is provided by a 2N333 that came off the GE assembly line in November of 1958. The DPDT relay is keyed directly. On transmit the 7MHz energy feeds a second push-push frequency doubler to produce 10mW at 14MHz (all spurs -35dBc, or less, with only the output resonator). The relay also switches the antenna between the transmitter and receiver.
Gosh, that was fun!

CT1BQH

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Bert's Pititico (PY2OHH) Rig (Video)

Bravo Bert!  

http://wf7ihomebrew.wordpress.com/2014/04/13/a-listen-on-40m-with-the-1-transistor-pititico/

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DSB Transceiver with Only 3 Transistors

Wow.  Looks like something Peter Parker would really like.  This one was sent to me by Stephen, G7VFY.  It comes from Japan:
http://www.cqpub.co.jp/hanbai/books/15/15061/15061_p.180-181.pdf

From this book:-

http://www.cqpub.co.jp/hanbai/books/15/15061.htm

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"That 70s Show": Steve "Snort Rosin" Smith Restores a 70's era Tuna Tin 2

Hi Bill,

Your recent stories about your TT-2 and original TT-2 "mojo transfer" prompted me to resurrect my TT-2 'resto' project. 

The attached photos show my 70s era TT-2 obtained for $5 from a QRP-L member.  This is how I received it and you can see that it's almost a duplicate copy of the original, complete with 'phenolic' substrate PC board material and hand-scrawled traces. 

I have collected most of the components necessary to convert it to a look-alike of Doug Demaw's 1976 item.  I already have 1 or 2 of the proper Radio Shack RF chokes but lack one more to have the complete set and I'm about to grab some original Radio Shack 276-1617 transistors.  The rest of the missing/incorrect parts I can drag out of the ever expansive Snort Rosin junque box. 

By hand selecting the two transistors for max. power gain I hope to eek 300 mW out of the thing.

Anyway, hope you enjoy the shots and I'll send more when it's finished.

73.......Steve Smith WB6TNL
          "Snort Rosin"

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PY2OHH's New Super-Minimalist (11 Component!) QRPp Transceiver

Wow!   Check out the latest rig from PY2OHH, the Wizard of Sao Paulo,

http://py2ohh.w2c.com.br/trx/pititico/pititico.html


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Pete Friedrichs' Amazing Books, Projects, and Guests

H.P. "Pete" Friedrichs is the author of two books that belong on our book shelves: "Voice of the Crystal" and "Instruments of Amplification." http://www.hpfriedrichs.com/mybooks/mybooks.htm

This morning I got a nice e-mail from Pete.  He's been listening to the podcast.

His e-mail caused me to revisit his web site.  Lots of minimalist homebrew gold there!

Check out the collection of projects sent to Pete from all around the world by readers of his books: 

http://www.hpfriedrichs.com/guestgallery/guestgallery.htm

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QRPp Model Planes

Michael, AA1TJ, alerted me to this very interesting hobby.  The video is really beautiful.

http://floatdocumentary.com/documentary

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Parachutist's Helmet-Camera Images Falling Meteorite

Just because it is pretty cool.  Also, we like parachutes, meteorites, and Norway.

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SolderSmoke Podcast #159: Hamfests, Herring Aids, and Tuna Tins

 

SolderSmoke Podcast #159 is available.

 



http://soldersmoke.com/soldersmoke159.mp3

April 1, 2014
Vienna Wireless Hamfest
BITX Talk
W1REX speaks
Tuna Tin 2 Mojo Transfer Ceremony
After 38 years -- finishing my Herring Aid 5 receiver
Feedback, Phasing Dots, Rotational Sense, and Oscillation (or not)
Motorboating (when you don't want to)
Building my Tuna Tin 2 with parts from W1REX
On the air with Tuna Tin and Herring Aid
More Minimalist Meanderings:
An (Almost) All Altoid Crystal Radio!
Tek 465 dies (again) :-(
MAILBAG

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First Contact with Herring Aid 5 AND Tuna Tin 2

Ah, it was a good morning in the N2CQR shack!  Last week I ran into fellow ham David Cowhig at work.   I was regaling him with tales of Herring Aid and Tuna Tin derring-do.  Oh the stations I had heard with the receiver!  And the stations that I'd worked with the transmitter!   Then David asked the question: "Yea, but have you worked anybody with the receiver paired up with the transmitter?"  Uh, no.  Not yet. 

 

Well this morning I took care of that.  7040 kc.   1115 UTC.  W4ELP was calling CQ.  He wasn't too strong, and I wasn't sure if we were on the same side of zero beat (that's what happens with direct conversion -- you get all the sigs in two places on the dial) but I took a shot at it.  And he heard me! 

 

Here's the icing on the cake:  This was his SECOND QSO with my Tuna Tin 2!  Ed had been contact #4 when I was running the TT2 with the Drake 2B.   After exchanging reports he asked "Bill ARE YOU STILL ON THE TUNA TIN?" 

 

The rig (TX AND RX) is pictured above.   Close-up of the receiver appears below.  And below that is a picture of Ed, W4ELP, in his Georgia shack.  Note the HW-8.

 

Thanks Ed! Thanks David!

 



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Harv's DDS Function Generator

Nice looking DDS function generator Harv!  Glad to see the HT-37 in the background. (And it appears well protected -- is that some sort of digital shielding to protect it from the bits and bytes?) The eraser buttons are a nice touch. Good luck with the Minima!

Hi Bill,

 

Well I have nearly completed my DDS Function Generator as I prepare to construct the Minima.

 

The Function Generator was a necessity for the bench so I can tackle Tweaking and Troubleshooting my work.

It is housed an aluminum box and completely self-contained.

My objective was to have the choice, to either lay the unit flat on the work surface or stand it on a shelf for easy reading while seated.

The Generator has both a  DDS and HF-ECG output.

The buttons are fashioned from White Pencil Erasers since finding proper buttons for the membrane keypad beneath was difficult.

 

I have obtained a set of Farhan’s Boards for the Minima but will begin my effort with a Manhattan Style Construction so I can perfect my choice of parts.

The soldering iron is heating and I’m ready for a new and exciting challenge.

 

Happy Solder Melting Everyone!

 

Harv -=WA3EIB=-

Albq., NM.

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Remotely Controlled Stations on the Internet

Now for something completely different!  

I  find myself talking fairly often to hams who are using remote transceivers.  The operator will be in say, Michigan, with the rig in Florida.  Some of them are using the online system:

http://www.remotehams.com/

I signed up and downloaded the software.   It works very well.  Many of the stations are closed to outsiders, and some of them don't let you transmit, but it is fun to listen from remote locations.

This morning I hooked up the Tuna Tin 2 and was able to hear my 200 mW signal through AI4W's receiver in Kentucky. 

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Hackaday Goes to Shanghai

http://hackaday.com/2014/03/24/the-gathering-shanghais-hackaday-community/


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VU2JN's "Transistor Transmitter from India"

VU2JN

VU2INJ's very interesting blog led me to a wonderful 1967 QST article by VU2JN.  Check it out.  Necessity truly is the mother of invention and -- as is the case with our beloved BITX -- we see that in the design of this transmitter.  I love how the speaker was left in the cabinet and used as the microphone.  Check it out:

http://vu3inj.blogspot.in/2014/01/tribute-to-vu2jn.html

More on VU2JN (who very clearly merits "Homebrew Hero" status):

http://shipwreck1.hopto.org:8080/projects/hamprojects/VU2JNArchive/

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The Really BIG Discovery (Cosmology, Gravity Waves, Inflation)

The signals that were announced this week are a bit outside our normal frequency range, but this is a REALLY BIG discovery so of course, it needs to be covered by SolderSmoke Daily News. I liked this info-graphic from space.com. It is worth looking at. Note the line "The universe continues infinitely outside Earth's Hubble volume."

http://www.space.com/25075-cosmic-inflation-universe-expansion-big-bang-infographic.html

Source SPACE.com: All about our solar system, outer space and exploration.
Source SPACE.com: All about our solar system, outer space and exploration.

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A Short Video on my Herring Aid 5

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The Ladybird TRF (Regen!) Receiver

http://www.mds975.co.uk/Content/trfradios02.html

My feelings about regenerative receivers and their possible connections to the nether-world are well known.  But the receiver described on this beautiful British web site is almost enough to make me change my mind.  Thanks to Stephen, G7VFY, for alerting me to this (and to so many other great sites!)   I also find myself forced to give regens another chance because George Dobbs, G3RJV, was the original source of this design.  It comes from a book he wrote in 1972.    I love the wooden bread-board construction.  Thanks Stephen!  Thanks George!



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The Wizard of Sao Paulo

It has been about 4 years since Miguel, PY2OHH, has been mentioned in this blog.  That's too long!  Miguel has churned out an impressive series of homebrew rigs, the latest of which he calls the Baita Tche.  Does that name look familiar?  It is a play on words using slang from Southern Brazil.  "Baita"  means big or enormous.  "Tche" means "you."  Together they sound sort of like BITX!  Miguel has been building BITX rigs and rigs (like Baita Tche)  similar to Farhan's rig.  Here is his page on Baita Tche:
http://py2ohh.w2c.com.br/trx/baitatche/baitatche.html

Here is his home page with a LONG (almost JF1OZL-ish!) list of projects:
http://py2ohh.w2c.com.br/

Here's his YouTube channel:
http://www.youtube.com/user/py2ohh

Here's a Photostream of some excellent Brazilian homebrew:
 http://www.flickr.com/photos/py2jcm/2066764415/in/photostream/

Muito obrigado Miguel!

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Farhan's RM386 RF Amplifier

An RF amplifier inspired by a quest for an AF replacement for the LM386.  I like it!  Check it out:

http://www.hfsignals.org/index.php/RF386


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Herring Aid Motorboating STOPPED!

FIXED!   Following up on suggestions from Tony Fishpool and from Roy Morgan, I put a 10 ohm resistor between the two supply lines and put 100 uF caps to ground at either end of the resistor.   I can now operate the receiver at high AF gain (no problem running a speaker) without the KLUDGE of two power supplies.  The RX sounds great.    I will soon match it up with the equally awesome Tuna Tin 2 for 1976 QRP EXTRAVAGANZA. 

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Stopping the AF oscillations in the Herring Aid 5

Thanks to all who responded.   This morning I got a significant clue:  Following up on Tony Fishpool's suggestion, I separated the power supplies:  I ran the RF amp, oscillator and mixer base bias off a small 12 V battery, with the mixer collector circuit and the AF amps running of the bench 12V supply.   The AF oscillations completely stop under these conditions.  So the feedback is probably taking place via the 12 V supply lines.  73


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Direct Conversion Receivers, AF Transformers, and Motorboating

The Herring Aid 5 is a direct conversion receiver (scroll down for details).  It is a minimalist design from 1976 using parts available at Radio Shack stores.    One of the parts no longer carried by Radio Shack is a 10K-2K ohm audio transformer.  Following NORCAL's 1998 design update I ordered an equivalent Mouser part (Xicon 42TU002-RC).   I had been running the receiver with simple RC coupling instead of the transformer.

Yesterday the Mouser part arrived and I put it into the circuit.  An increase in AF gain was immediately apparent, but the thing went into AF oscillation as soon as I turned up the AF gain. 

I tried beefing up the AF decoupling.   But I think the real problem is just the presence in the middle of the board of a rather large (1 inch x 1 inch) audio transformer.    I moved it around a bit to get it away from the toroid of the preceding stage.  This helped a bit, but it still breaks into oscillation if I turn up the AF gain.

Any suggestions?  Or is this just part of  the minimalist 1976 lifestyle?  


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German Radio Amateurs Receive Signals from ICE Spacecraft

The wizards at AMSAT-DL have done it again!  Their latest feat of outer space derring-do is the reception of the 5 watt (QRP!) signal from the lost (now found) ICE spacecraft.  Details here:
http://amsat-uk.org/2014/03/09/radio-amateurs-receive-nasa-isee-3ice-spacecraft/

Here is their facility:

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I Too Built a Tuna Tin 2

I didn't plan on doing this.  I didn't even really want to do this.   I've become a phone guy -- I'm not into CW anymore.  I figured I'd just finish the Herring Aid 5 receiver and settle the score from 1976 and that would be it.  But everything I read about the Herring Aid 5 included references to the iconic Tuna Tin 2.  Obviously I was also under the strong influence of my late February encounter with the original TT2 at the Vienna Wireless Winterfest.  That Mojo is powerful stuff!   Then my wife brought home this can of Russian tuna.  The dimensions were perfect.  Then I looked in my junkbox and found 40 meter CW crystals.  That was it. I had to do it. 

I built mine Manhattan style, using several of W1REX's fantastic Me-pads.   I also used as the final a transistor that Rex gave me at Winterfest. Thanks Rex.  Soul in the New Machine. 

I'm getting about 200 mW out.  I;m on 7030 kHz and 7040 kHz and 7110 kHz.   I have the TT2 up with my Drake 2-B (Herring Aid 5 integration will come later).  I can feel the Mojo. 

I just had my first contact with the TT2:  I called CQ on 7110 and AB2RA came back.  Jan was running 20 watts from an old 807 rig, listening with an old Hammarlund.  So it was HB transmitter and vintage receivers on both ends!  FB!





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Lulu Book Sale, Job Openings

Lulu is running a 20% off sale on books.   You can pick up SolderSmoke -- The Book at a discount.  Just use the coupon code SUPER20  :
http://www.lulu.com/spotlight/soldersmoke

And as long as we are talking about money, I spotted some job openings that might be of interest to readers of this blog: 

http://makezine.com/2014/03/06/wanna-work-for-us/

http://hackaday.com/2014/03/06/were-hiring-2/


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Some notes on the Herring Aid 5

Sure, this receiver is not "state of the art."  But that's the whole point.  I wanted to finish the receiver project that I couldn't finish back in 1976. 

I tried to stick as close as  possible to the original design and parts.  NORCAL came up with an updated schematic in 1998 with parts that are more readily available.  But Designer Jay Rusgrove was shooting for something that could be built with all the parts coming from Radio Shack.   I think that is probably one of the factors that attracted me to the project way back when.  That's why Jay went with varactor tuning (no hard-to-get variable caps!).  And that's why he used coils that were wound  on Radio Shack 10uH RF chokes (no need for hard-to-find toroidal cores).  In this sense there is some common ground between the BITX rigs and the Herring Aid 5.

I stuck with the RF-choke as a coil idea for the VFO, but went with the NORCAL-prescribed toroids for the front end and mixer coils.  (I may go back and try to use chokes in these circuits, but I'm not sure my junk-box will yield the kind of RF chokes that Jay used).

I wish I had known a few things when I was building this back in 1976: More knowledge about how to wind the coils would have been a big help.  I wish I had realized that I could use a SW receiver to get the oscillator on the right frequency. I guess this was in the days before Ugly and Manhattan building techniques, but it would have been nice to know that there was no need to actually etch a board for this project (I did!).

The coils really are a bit tricky.  Jay didn't use any trimmer caps, so I guess you had to just hope that the front end coil and cap resonated somewhere near 40 meters.   As for tuning the oscillator, Jay recommended scrunching and un-scrunching the turns on the RF choke.  Yikes!  Give me some trimmer caps! 

I also found that you have to watch the level of the RF going from the oscillator to the mixer.   Too much, and the receiver is deaf.  Too little, same result.    You need to experiment a bit with the number of turns on the pick-up coil from the oscillator.   

The warnings about the pitfalls of that single BJT mixer were right on the mark:  Lots of AM SW breakthrough.  But I kind of like the background music.   Strong RFI from local FM broadcast stations was another story (WMZQ is a country music station!).  I reached into my junkbox and found a low-pass filter from a Heathkit DX-60.    I just put that between the antenna and the receiver and the country music was GONE! 

I really love this little receiver.  I have it playing 40 meter CW as I type.  It sounds great.   I feel the urge to built a Tuna Tin 2 and put both of them on 40. 

In the original Tuna Tin 2 article, Doug DeMaw notes that Jay Rusgrove was thinking of doing a companion receiver and says that he was thinking of calling it the "Clam Can 5" !  There were jokes about receivers for hams with "tin ears" and about there being "something fishy" about these rigs.

Thanks to Doug DeMaw and Jay Rusgrove and QST for bringing us these little circuits. 


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Herring Aid 5: Working after 38 years!

I know, it is just a little Direct Conversion receiver.  Getting it going is no great technical achievement.  But this little receiver gave me such trouble as a teenager, it has been in the back of my mind for a long time.  Finally, yesterday afternoon it started picking up signals. 

I felt a bit bad about insinuating (a few days ago -- see below) that QST may have made an error in the 1976 schematic.  They didn't.   So it was kind of spooky when I heard that first call-sign coming through the speaker:  It was W1AW!  It was as if they were saying:  "See, the schematic was correct!"

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Herring Aid: It was NOT the dots! Rotational Sense and Phasing

Opposite "sense" winding and resulting phase shift

My second attempt at building a Herring Aid 5 (the first was 1976) continues. 

I thought I had discovered an error in the schematic that (I hoped) explained my failure to get this simple receiver running (scroll down for details).  But Dex, ZL2DEX,  in New Zealand spotted something that got QST off the hook and put all the blame back on me:

I had failed to check the rotational sense of the windings.  The schematic called for 4 turns over the Radio Shack choke.  So I just went ahead and wound them.  I didn't pay any attention to the direction of the winding.  I then hooked it up in accordance with the phasing dots in the diagram.  And it didn't work.  So I switched the coil connections around.  And it worked.  Aha! I thought! QST messed up!  It wasn't my fault. 

Dex brought me back to reality.  He noted that I probably wound the coils with the wrong rotational sense.   I confirmed this.  I rewound the coil following the rotational sense of the choke.  I hooked it up following the phasing dots of the schematic.  This time the oscillator started right up.  So the problem wasn't an incorrect drawing of the phasing dots.  Instead it was my failure to remember that phasing is more than just the top or the bottom of a transformer's winding.  Rotational sense is also important.  That's why "phasing dots" are sometimes referred to as "sense dots."

This doesn't come up very often, because most of the toroidal transformers we make are bifilar or trifilar -- the windings are always in the correct sense because we twist the wires together before putting them on the coil.  When we look at those phasing dots, we are focused on getting the proper tops of coils connected to the appropriate bottoms of other windings.  We don't pay any attention to the sense of the windings.  Thanks to Dex for bringing me back to my senses :-o

Grob's Basic Electronics has this definition for those phasing dots:

"	Used on transformer windings to identify those leads having the same instantaneous polarity."

This morning I did a little experiment to confirm all this:  I took a toroidal core and wound a little transformer.  Using a dual trace scope, I looked at the input and output wave forms.  Sure enough, when the windings are in the same rotational sense, there is no phase shift.   But when that secondary is wound in the opposite sense, you get a 180 degree phase shift.  I know this is very basic, but it was fun to re-learn it and to confirm is.

But I still don't have the little receiver running.  I think there are a few problems.  That single BJT mixer stage needs a lot of RF (2.5 volts p-p) from the oscillator.   Also, I think the 10 uH chokes that I am using are not the same as the chokes used in the original Herring Aid design.  So when I build transformers on these chokes, they don't work very well.

But I will keep at it.  It has been 38 years... I can wait another week or two.   

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38 Year HB Mystery Solved? Was it the phasing dots?

 During the summer of 1976, at the age of 18, I made an audacious attempt to join the ranks of the true homebrewers.  I tried to build a receiver.  It was the Herring Aid 5 from the July 1976 issue of QST, a 40 meter Direct Conversion receiver intended for use with the famed Tuna Tin 2. As I have recounted (perhaps ad nauseum), I never got it to work.   My recent encounter with the ORIGINAL Tuna Tin 2 (Mojo was transferred to my BITX17, and it definitely works better now) got me thinking about this painful experience.   I decided to try again.

There is an updated NORCAL schematic for this rig.  I found it (and some good articles) on the NJQRP club page.   In the original, designer Jay Rusgrove, WA1LNQ, used only parts that could be found at Radio Shack stores.  In the days before the internet and Mouser, this was a good idea.  Instead of toroidal ferrite and iron powder coils,  Jay built his coils around Radio Shack solonoidal 10 uH chokes. 

The NORCAL version dispensed with the Radio Shack chokes, and used toroids.  But I wanted to try to find out what went wrong 38 years ago.  So I dug up some 10uH chokes. 

I know that my problem was that I never got the oscillator working.  I remember being able to hear signals with my "almost" receiver when I put my HT-37 in "CAL" mode and tuned through 40.  I was so close!  The Herring Aid was picking up RF from the HT-37 and using that in lieu of the LO energy that obviously wasn't coming from my Herring Aid VFO.  But WHY didn't that oscillator work?

Today I started with the VFO.   Again, it didn't work!   But now I have decades of troubleshooting experience under my belt.  So I poked around a bit.  Then I decided to look closely at the phasing.

Take a look at the schematic(above) and the picture (below).  L7 is the 10uH choke.  L6 is 4 turns wound over it (or adjacent to it).  Now, here is the key question:  Look at the phasing dots.  How would you guys connect those coils?   For me, the schematic indicates that the TOP of L6 should go to the Zener and the BOTTOM of L6 should go to the drain of the JFET.   The TOP of the choke should go over to C5, and BOTTOM of L6 should go to ground.  Right?  Or am I reading the phasing dots wrong?

Well, the oscillator was not oscillating in this configuration.  Then I did something that I might not have known to try back in 1976:  I reversed the phase of L6:  I put the top of the coil to the Drain of the JFET and the bottom of the coil to the Zener.  Bingo.  The joy of oscillation.  Now it works.  (The picture below shows it as it is when the oscillator is working well.)

So,  is there an error in that diagram?  Was this not all my fault?   

Aha! I just looked at the schematic of the NORCAL version.  Check out the dots!   I think that was the problem!

 

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Links Fixed, Podcast Version of Hamfest Presentation

Armand, WA1UQO, with BITX 17

 

Using Dropbox to post the video of my BITX presentation at the hamfest didn't work out too well, so I put it on Vimeo:

 https://vimeo.com/87725154

The slideshow is here: http://soldersmoke.com/winterfest.pptx

I stripped out the audio for those who would like to dispense with the video.

Audio only is here: 

http://soldersmoke.com/soldersmokewinterfest.mp3

73

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Hamfest Presentation on SolderSmoke and BITX (Video)

The Vienna Wireless Society of Northern Virginia asked me to give a talk at their 23 Feb 2014 hamfest.  I spoke about homebrewing and the BITX transceivers.  Click on the link below to watch the video.  (Special thanks to Elisa for doing the video.)

https://vimeo.com/87725154

The Powerpoint slides are here:

http://soldersmoke.com/winterfest.pptx

For those who just want to listen podcast style,  I will try to turn the audio into a podcast and will post it via the normal channels. 


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HB Chips! Discrete Component Version of 555 Timer

The world would be a better place if we could do more of this...  Thanks to David Cowhig for alerting me to this wonderful development. Details here:

http://spectrum.ieee.org/geek-life/hands-on/build-your-own-giant-555-timer-chip


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Tuna Tin Mojo Transferred to BITX17!!!!!!

It happened at the Vienna Wireless Society's Winterfest Hamfest today in Northern Virginia.
That is Doug DeMaw's original Tuna Tin. 
This may be the first time TT Mojo has been given to a phone rig. 
Doug DeMaw would, I'm sure, approve.

Thanks Rex!


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Brilliant! New "TX Factor" Ham Radio TV Show from the UK

I really enjoyed this.  It is the first episode of what I hope will be a long-running series.
These guys did a great job.  Excellent quality video production and very interesting subject matter. A LOT of work went into this.  I liked the PSK from a smart phone on a foggy hillside (with Moroccan soup!).  The Marconi stuff was wonderful.  Beer barrels as 2 meter cavity resonators! Excellent Knackish-ness!  And a two meter repeater in an astronomical observatory.  Well done! 

Thanks to Nigel and Dino for alerting me to the TX Factor.

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Taking the Knack a Bit Too Far

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BITX 17 Build Update: More Filter Maintenance

 

 

 

Having had great success in straightening out the 11 MHz filter in my BITX 2040 (scroll down for details),  today I decided to see what I could do with the filter in my 17 meter BITX (four 5 MHz crystals in Cohn MIN LOSS configuration, with 40 pf caps all around).  The key to my success in all this has been the filter programs that came with EMRFD.  After characterizing my crystals with the G3UUR method, I plugged the values into LADBUILD 8, then took a look at the expected results.  As you can see from the image above the predictions were not pretty.  Yuck.  Lots of ripple and lots of insertion loss.

I went into the rig and using my DDS sig generator and my RIGOL 'scope, measured actual performance.  It looked worse than the prediction (part of the worsening is a difference in vertical scale):

LADBUILD lets you play around with the values of the components in the filters.  I know that ripple is usually related to an impedance mismatch.  So in LADBUILD I experimented (virtually) with different impedance values at the end.   I noticed that at about 1000 ohms, the ripple and insertion loss got better:

So I went and built two broadband toroidal transformers.   4 turns primary with 12 turns secondary (1:9 Z).  I'm assuming that the BITX has around 150 ohms at either end of the filter.  That would put about 1350 ohms at the ends of the filter.

Here are the results:

Much better.



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ISEE-3 Spacecraft Returns after Being Forgotten

Hack-A-Day has issued a challenge to hams and hackers:

http://hackaday.com/2014/02/14/call-for-hams-and-hackers-welcome-iceisee-3-home/#more-114769

If a BITX 20/40 would help, I stand ready to assist!  


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Homebrew Junkbox Machine Tools

In the book "The Ugly American"  the hero (the ugly guy!) come up with a way to use old engine blocks to build water pumps to help farmers in South East Asia. Now, Mr. Delany is putting them to similar good use.  Homebrew junkbox machine tools!  Yea!

http://makezine.com/magazine/make-37/patdelany/

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BITX 2040 Build Update #10 : Fixing my Filter

That dip on the high side of the passband was bothering me.  The GPLA crystal design program predicted it, and indeed, when I measured the performance of the actual filter, there it was.   The rig was working fine -- the receiver sounded fine and everyone tells me that it sounds great on transmit.  But still, it bothered me.

So I started working out with the various crystal filter software packages.  

This filter was -- sort of -- a Cohn Min-loss filter, but I had built it with four crystals and three shunt caps (80 pf each) and no series caps at the input/output.  This morning I decided to see what would happen if I put the series caps in there.  Here is what Wes's GPLA predicted:

Wow, that looked a lot nicer.  And the 150 ohm terminations seemed to be just about perfect for the BITX design -- no need for impedance transformation.  I heated up the soldering iron and searched the junkbox for suitable caps (I found 2 82 pf caps -- close enough).

Here is what the results looked like (I didn't measure insertion loss so the top of the curve is just the peak of the response curve).

Exactly as predicted!  Thanks Wes! And thanks to Farhan for encouraging me to characterize my crystals and to use the available software

Now I have to go back and de-ripple the 5 MHz filter in my BITX 17.

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Back to the W7ZOI/W7PUA Power Meter

Recent e-mails and Facebook postings from Jim (W8NSA) and Michael (AA1TJ) got me thinking about my old W7ZOI/W7PUA power meter.  The 15 inches (38 centimeters) of snow that fell last night gave me the day off -- and time to play with this very useful and interesting piece of gear. 

The last time I used it I remember thinking that a digital readout would be nice.  But I didn't feel like going back into the world of Arduinos and LCD screens.  So I came up with a real Kludge solution:  I had cheap little DVM that I wasn't using, so I just velcroed it to the side of the power meter.  That little connector above the BNC is the output for a DVM.  I might work on calibration later today.

Wes has some very interesting info follow-up info on the meter on his site: http://w7zoi.net/qststuff.html
I really like the part about how the meter is so sensitive that you can see the thermal noise in the input circuit and can actually measure the strength of signals from your antenna. 

I think I might need a low pass filter at the input of the meter.  There are strong FM broadcast transmitters in this area (some of you may have listened to them in the background of early episode of the SolderSmoke podcast!). I notice that just bringing my fingers close to the input causes the meter and the DVM readout to swing up.  That's not good.

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