A Package from Hyderabad: Farhan's BITX 40 Module Arrives in Virginia

I am having a really EXCELLENT radio morning here at SolderSmoke East coast HQ.  I made some progress on the Armand HRO receiver -- just squaring away some of the too-long leads and improving the shielding a bit.  Then I was looking out the window as the mailman arrived.  What was that little box he was leaving us?  Wow! A box from Hyderabad!  The BITX 40 module arrived, wrapped in a very interesting piece of Hyderabad newspaper. Very FB. Thanks Farhan.  I will surely be writing and talking about this rig in the weeks to come.

UPDATE:  I just realized that the BITX module fits very nicely into a TenTec TPC-45 cabinet that Armand gave me a while back.  TRGHS.

Cool Jazz from New Zealand as Heard on a Homebrew Superhet Receiver (VIDEO)

I'm making slow but steady progress on this one.  The origin of the project was the beautiful National HRO dial and gearbox that Armand WA1UQO gave me. 

I decided to use a 455 kHz IF because;
1) That was the IF of the old HRO receivers (the ones that won WWII)
2) I had a nice TOYO CM455 crystal mechanical filter that would be good for SSB.
3) I figured it would be easy to add in a wider filter that would be good for AM shortwave listening.
4) I like to keep the IF below the frequency of the VFO.

The wide filter turned out to be harder than I thought, but I think I have finally achieved the selectivity I was looking for.  I'll have a switch on the front panel that will allow me to go from "AM-Wide" to "SSB Narrow." The switch will change the filters and the detectors, and will turn the BFO on and off.

Still to do:  I need a high-pass filter to knock down RFI from nearby AM broadcast transmitter. And an RF gain control would be nice.

I'm really glad Radio New Zealand is there.  It provides welcome relief from the shortwave fire and brimstone.   Radio Romania is also doing a fine job on shortwave.

The Last Hallicrafters Transceiver...REBORN! TWICE!

Pete Juliano and his colleague Giovanni Manzoni led me this morning to the happy land of Hallicrafters hybrid nostalgia.

It all started with Pete's latest blog post:  
http://n6qw.blogspot.com/2016/10/more-junk-box-rigs.html

I admit that I had never even heard of the Hallicrafters FPM rigs.  Pete's (uh, I mean Giovanni's) video show's Pete's junk-box rebuild of the old rig.  Very nice.   Note the presence of the Si5351...

I needed more background info, so I turned to YouTube.  This led me to more old friends:  Dale Parfitt W4OP has a really nice video of his rebuild of the Halli FPM rig (see above).  From his video we learn why Dr. Juliano prescribed a dose of Si5351 for the patient:  Dale tells us that VFO instability was a major problem with this rig.   Dale fixed his with the addition of an X-Lock board from yet another friend of SolderSmoke: Ron G4GXO of Cumbria Designs. 

Dale really out-did himself by building an add-on accessory box for the FPM.  Very nice.  I especially liked the addition of the W3NQN passive audio filter for CW.   I always have misgivings about adding audio filters to Direct Conversion receivers -- this will reduce QRM, but you are still listening to both sides of zero beat.  But when you add a sharp CW audio filter to an SSB superhet you will end up with true "single signal reception."  FB Dale.  

Please send Pete Juliano and Giovanni Manzoni some positive feedback and words of encouragement.  Please urge them to keep up the good work on the blog and the videos.  Theirs is sometimes a lonely task -- without feedback it can sometimes seem like putting messages in a bottle and throwing them into the digital sea.   Please let them know that their work is being seen!  Leave some positive comments on Pete's blog.  (No snark please -- The Radio Gods will retaliate if you harsh N6QW's mellow.)

Oz Tektronix 'Scope Repair (in Juliano Blue)

Rob is a braver ham than I.  When my Tek 465 quit, I tried to fix it, but quickly chickened out.
Very nice that he painted his in Juliano Blue.

Dear Bill and Pete, 

I do enjoy your podcast, and I must present an offering to the "Gods of Homebrew", 

An on-line find of an old Tek 545 oscilloscope presented a chance to enjoy the warmth of 100+ tubes (once repaired)

The outside was heavily scratched, the inside looked like a chicken coup, but no major bits missing or broken. 

Lots of cleaning, testing all tubes,(using the excellent uTracer tube tracer),  replacing the broken 3, remounting the cooling fan, lots of reading about tube oscilloscopes, adjusting the trigger circuit, rebuilding 3 electrolytic power supply capacitors, sandblasting the cabinet and a coat of BLUE paint. 

Voila,  the joy of (visual) oscillation!     (1MHz 2V p-p)

Rob VK5RC

Colin M1BUU's New Receiver Project

Hi Pete,

Just checking in :-)

I have actually been melting solder recently. I decided to build a little CW receiver. I love my regenerative RX that I built as a teenager, but after all these years, I'm tired of constantly tweaking the controls!

My project is a 20m CW only superhet receiver with a 9MHz home brew filter. I'm using the SI5351 for the oscillators. I originally thought I would cover multiple  bands, but for now I have the parts for 20m coverage. I might tinker with other bands at a later point.

I'm using your LBS code on the Arduino, the one for 20m with 9MHz IF. I haven't applied power to the rig yet but it's not far off fully built. I tweaked the Arduino sketch using my Uno and tonight I have successfully transferred the code to a Pro Mini. (Code went into Pro Mini on first attempt - amazing!).

73 for now,

Colin M1BUU

Beautifully Ugly! A Homebrew Receiver from the Netherlands (video)

This one is similar to the receiver I've been working on:  middle of the HF band, discrete components, all analog, 455 kc IF, wooden chassis, eclectic circuit boards.  Very cool.

The builder is Ko Tilman.  His YouTube channel is here:
https://www.youtube.com/channel/UCqe1Y4StR9cZ8BQDWuoMq9w

I came across Ko's channel when I was looking for a circuit for an AM detector.   I have been  experimenting with the standard one diode and two diode (Germanium) circuits, but the receiver doesn't sound very good when using these circuits.   Any recommendations for something a bit better (without getting carried away with complexity)?


About Ko Tilman:

Ko Tilman (1955) lives in the Netherlands and is active in electronics since 1967. His focus is on analog electronics, audio, shortwave radio's, small (solar) energy systems and measurement and control systems. He is the author of "Retro Radio", Isbn 978-90-5381-234-1, published by Elektor International Media in the Netherlands. In this book (Dutch text) you will find several simple schematics from Shortwave radio's (2 MHz - 16 MHz), including radio's with SSB reception. His long time knowledge about small audio systems (for household use) is available in his book "Schematics 2, audio amplifiers and loudspeaker boxes ", available on this website (a summary of the content is visible). Also in an E-book format: Isbn 978-1-4475-7336-4. In the past (2008-2010) he was active on You Tube under the name "radioam232", now he is active on Youtube as "radiofun232". A free download from the activities in the "radioam232" period is available on this website in the content "blueprints 1".

Ko's Books: http://www.lulu.com/spotlight/radioam232

Smoke-Free! On the Air with the W1REX Dayton Hamfest Buddy

After the Dayton Hamvention, our ace correspondent Bob Crane (W8SX) sent me the "Hamfest Buddy" kit that Rex Harper W1REX had put together and used in "The World's Biggest Build-a-Thon."

It is a single 2N2222 crystal-controlled oscillator for 20 meters.   All the parts are plug-in -- no solder smoke is released.   Mine went together in about 15 minutes and fired right up.  You can see it above.  It runs off the 9V battery. I had to hold it down with tape.   You can see the key button in the lower right.  That little inductor in the foreground is used to shift the frequency a bit.  I had to remove the 10K resistor in the emitter circuit because with my antenna the circuit was going into low-level oscillation even in key-up.  With the 10K resistor removed, this problem disappeared.

I hooked it up to my 20 meter dipole and called CQ.   With only about 60 milliwatts into a dipole under poor conditions, I really didn't think I'd get any answers.  But I figured the Reverse Beacon Network might pick me up.  It did:

Thanks Bob!  Thanks Rex!

HB2HB! KW4KD and N2CQR (video)

A couple weeks ago I ran into Jim KW4KD on 40 meter SSB.  Jim is in Chattanooga, Tennessee.  He was running a modern "black box" rig, but he mentioned that he had on the shelf two complete homebrew stations, one of which was for 40 meter SSB.  He hadn't used this gear in 40 years.  I encouraged him to blow the dust off and get it on the air.  Yesterday, Jim did just that.   We met up on 40, first at 1730 local (my time) and again at 1930.   Excellent!  Another HB2HB contact.  Check out the video (above).   Thanks Jim.

If you run into someone who mentions having some old homebrew gear, encourage them to blow the dust off and get it on the air.

Jim's SSB rig:

The Invention of the Reflectometer: Naval Research Lab Report #3538

Dennis Klipa N8ERF has been doing great work exploring the technical intricacies of the humble SWR meter (and believe me, there are intricacies).   He's also been looking at the history of this invention. 

This summer, Dennis and I came across the April 1964 issue of Popular Electronics.  On pages 74 and 75 of that issue we found a clue that seemed to point to the origins of the device:  the article referred to Naval Research Lab Report #3538 by O. Norgorden,  published on September 15, 1949.  This may be the paper that led to the widespread use of SWR meters by radio amateurs.

Surprisingly, this important paper was not to be found on the internet.  Exhibiting an admirable dedication to the preservation of an important element of the radio art, Dennis wrote to Naval Research Lab and purchased from them a copy of the report.   Unfortunately, the version Dennis got had been copied and recopied so many times that it was hard to read.  So he went the extra mile and re-typed it. 

With his permission, I am giving this article its internet debut by posting it here:

http://soldersmoke.com/SWR N8ERF.pdf

Three cheers for Dennis Klipa for unearthing this important piece of radio history.

From the Wizard of Wimbledon: Matchbox Junkbox Rig

Dear Bill

I hope that life’s treating you kindly over the left side of the pond. Your latest podcast really resonated with me as I’m hugely fond of junk box projects on a rainy afternoon. Fortunately Her Majesty’s weather men are generous...

Spy gadgets have long been a fascination of mine, particularly those disguised as harmless everyday objects. I remembered a Soldersmoke blog post a few months back showing a radio hidden inside a book. That got me thinking… then one rainy afternoon I stumbled across a half-used box of matches – surely an ideal enclosure for a covert spy transmitter!

Objectives:

1.    The matchbox should remain fully functional and pass casual inspection
2.    Transmitter, Morse key and battery should be hidden within the box
3.    All parts should be cobbled-together from what I can find around the house
4.    To build using “Manhattan style” construction for the first time

The transmitter borrows heavily from the Pixie 2 circuit and is based around two PN2222A transistors: the first forms a Colpitts oscillator for 7030kHz (plus/minus a smidgen of capacitor trim), the second acts as a modest Class C power amplifier (approximately 170mW out) – keying occurs here, to minimise chirp, before feeding a simple low-pass filter. 

Discrete contacts set in the cardboard allow Morse to be keyed with my grandmother’s old sewing thimble – not only is this beautifully stealthy but it’s remarkably ergonomic too!

The transmitter can be easily teamed with an external receiver, selectable via a double-pole-double-throw switch. The switch simultaneously disconnects the battery, eliminating the audible whistle from the constantly-running oscillator.

This was my first experiment with “Manhattan style” construction and I can see why you swear by it. Even though I sketched the circuit’s layout before I started, I still found myself occasionally popping-off a square with a blade so as to optimise the tight packaging; Manhattan made this trivial, and fault-finding would have been easy with all connections on one side…

But remarkably the transmitter worked first time! Bench testing by calling CQ whilst monitoring the Reverse Beacon Network demonstrated that its tiny signal could be picked up as far away as northern France when driving my resonant end-fed antenna!

Ever since I discovered the magic of QSL cards I have always wanted to send one showing a hand-drawn diagram of my transmitter; perhaps I’ll now have a chance!

Please keep up the great work: you, Pete and the global brotherhood never cease to throw up new tricks for me to try. It’s a shame that this is perhaps one radio which I’d be best advised to not try to carry through airport security when my ever-patient girlfriend grants me permission for a holiday-time QRP operation...

73

Jonathan

M0JGH

--------------------------------

Earlier post about Jonathan: http://soldersmoke.blogspot.com/search?q=M0JGH

Update on Farhan's BITX 40 Module

It is truly a thing of beauty:  http://www.hfsigs.com/   

The boards come assembled (as seen above).  You can then add peripherals and modify away.  It is "hackable."

Hackable

The BITX40 will inspire you to experiment. Modify it, mount it, tweak it, change it.
The PCB uses all analog large sized SMD components that are laid out on an easy to understand manner on a double sided board with broad tracks. This can be your main module around which you can start experimenting. There are jump-points from where you can add more modules like the DDS, more bands, better audio amplifier, etc. Imagination is your limit. You can separately increase the power amplifier's supply voltage to 25 volts to be more than 20 watts of power : You will have to add a better heat sink. The mods are on the way!
The board can be installed inside any box that you like. Make your own station rigs, man-packs, trail radios or mount it in a cigar box and leave it on your bedside table. The tuning capacitor has been replaced by a varactor tuning so you can place the tuning knob anywhere as it only carries a DC voltage.

Farhan writes:

For the last few months we have been working bringing low cost, tested SSB boards. Finally they are here. Priced at Rs.2200 At the moment, they are available only in India until we sort out an inexpensive way to post them to other countries. Visit www.hfsigs.com and pick up one!

The BITX40v3 is a complete 7 MHz SSB transceiver on a board that puts out 5 watts of clean audio and it has a very crisp, all analog receiver. It is based on the popular BITX circuit. It is a high quality double side, PTH PCBs with machine assembled SMD components, hand wound coils and each of them is individually tested. All the connectors and wires needed are included in the kit.

JH8SST/7's Build of Pete's Simpleceiver

Beautiful. 

Makes me want to put S-meters in my rigs.

More on Pete's design here:

http://n6qw.blogspot.com/2015/09/simpleceiver-40m-ssbcw-receiver-and.html