My Extroverted BITX40 -- On (but not in) a Box

I was going to put the BITX40 Module in a box today, but I just couldn't bring myself to do it. That board looks too good to be hidden inside a box.  So I put it topside. That's the analog VFO to the right. You can see a fan off to the left -- that is perhaps temporarily in lieu of a large heat sink for the final. You can see the two Gel cells in the background.  I am indeed running 24 volts to the final, and am putting out about 20 watts.  I had three nice contacts today on 40:  WB2RON up on Long Island said I was "20 over".  Later I worked W1SJ in N. Vermont -- I was 5-9.  Then -- icing on the cake -- DK1NO in Stuttgart.  I was 5-8.  TRGHS.

I kind of like this arrangement -- it has the "three dimensional" feel of an old tube rig.  This obviously wouldn't be good for portable operations, but I am not planning on going portable.   There is a lot of room under the chassis.   I could put a digital VFO in there and put in a switch so that I can easily go from digital to analog.

Two Gel Cells and a Heat Sink -- BITX40 Power Hack

I blame Pete for this.  And Farhan.  Pete has been leading us astray with all his talk of high power linear amplifiers ("Two 813s kid, that's all you need!").  And Farhan practically pushed us beyond QRP limits by placing a separate DC power connector for the IRF510 final amplifier on his new BITX 40 Module board.  Farhan writes: 

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! (from hfsigs.com)

A while back Chris KD4PBJ sent me some very nice heat sinks -- one of those would fit quite nicely on the PA side of the BITX40 board.  And I just happen to have two 12V Gel cell batteries. One will power the board and the two together will power the IRF510.  With 20 watts out to my dipole I feel confident that I will WIN the upcoming ARRL Phone Sweepstakes (in my category: Homebrew VFO, Northern Virginia).  

Military Radios on Hackaday

http://hackaday.com/2016/11/09/resurrection-pressing-ww2-radio-equipment-back-into-service/

SolderSmoke Podcast #191 RIGS! REAL RIGS!, BITX40 Module, EMRFD, MAILBAG

SolderSmoke Podcast #191 is available:

http://soldersmoke.com/soldersmoke191.mp3

TRAVELOGUE AND FAMILY DOINGS:   Pete son's wedding, Billy's Birthday, Gonzalo safely home in the Dominican Republic, MORE BEARS IN THE SHENANDOAH WOODS

BIG NEWS:  EMRFD LIVES ON!   Three cheers for Wes and for Tom Gallagher of the ARRL.

BENCH REPORTS:

PETE:   FPM Rig.  Some Halli history.  A TRUE RIG!  Working Japan. 

             WITH 600 WATT LINEAR AMPLIFIER!!!!!!!!!!!!!!!!!!!!!!

               New FEELTECH  Sig Gen.  

BILL: Farhan's BITX Module

           Built to Mod, built to get you started in homebrew

           Very impressive.  BITX in miniature.  But completely recognizable.

           REMARKABLY stable.

           Farhan personally checking each one.

           Ladies collective doing toroids.  DONATION money bought them some Diwali candies!

           VFO Drift:  Will NP0 SMD caps and lower current help enough?

           My Analog VFO -- BANDSWEEP

QRPppppppppppp  with REX's Hamfest Buddy.   Thanks Rex and Bob Crane.

HB2HB with KW4KD

MAILBAG

Jan's Netherland Mate Mighty Midget

Charlie's Kiwi DSB

Steve, Donald Fagan, and Jean Shepherd

Rob VK5RC repairs Tek Tube 'scopes

Colin M1BUU Si5351 superhet

Denis Klipa and NRL 3538

Jonathan M0JGH Wizard of Wimbledon Matchbox rig

JH8SST Simpleceiver

Peter Parker Vk3YE Reviews Book

Peter GW4ZUA Welsh LBS

Michael Rainey helping hobbyist in Germany with tuning forks.

Reverse Polarity Protection

When I opened the package from India and saw Farhan's s beautiful board with all those little SMD parts, I immediately worried about frying those parts by accidentally reversing the polarity of the 12 volt DC input.   Believe me, this can happen.  It is especially likely during the early, enthusiastic testing and experimenting that takes place in the days after the arrival of a new rig.  So, my friends:  Save yourselves the agony of fried components!  Don't let your BITX 40 Module go up in smoke!  Install a simple reverse polarity protection circuit BEFORE you start working with your new board. 

Here is what I did:   I just took a diode (a fairly hefty diode) and I soldered it in between the pins of that neat little circular power jack that Farhan sent with the module.  Be sure to solder it in so that it does NOT conduct if you have connected the power correctly.  The arrow should be pointing to positive terminal.  Then put a fuse (3 amp or even a 2 amp) in the line from the connector to the power supply or battery.  If you don't have a holder you can try just soldering the fuse into the line.

With these two little parts, you can save yourself a lot of grief:  If (WHEN!) you connect red to black and black to red, that diode will conduct like crazy and will blow the fuse.  You'll just have to replace the fuse (and not the module).