PA3CRX's 6 Meter BITX in an Old CB Case

Thanks to Rogier PA1ZZ for alerting me to this video and to the PA3CRX YouTube channel. 

I like what Chrix did with the old CB transceiver case -- this gives me ideas about the old transceiver that I picked up at a hamfest a while back.  I also like Chrix's practice of running coax and power leads UNDER the main BITX boards.  

Chrix has been building some great stuff and making some very nice videos -- I have put his channel on the SolderSmoke links in the right-side column of this page. 

M0NTV's Latest Breadbox Rig -- The Radio Gods Have Spoken (TRGHS)!

Tony G4WIF sent me this video from Nick M0NTV.  It presents Nick's latest Bread Bin project -- "The Optimizer." 

-- I really like the Bread Box enclosures.  And leaving the b and the d on the box is just brilliant.  These letters now stand for BiDirectional!  They even appear symmetrical.  TRGHS!

-- The switch for a tuning tone is a great idea.  I still have to plug my Maplin AF sig gen into the mic jack to do this.  FB. 

-- I too have the connector on the back for keying the outboard linear amplifier.  (Shhh! Don't tell G-QRP!) 

-- As for the bidirectional TIA amps.  I'm really glad that someone else is using these circuits.  Wes's article came out in 2009 and concluded with a call for someone to build a complete rig with these circuits.  I wonder how many rigs like this have been made.  It is a great circuit.   One thing I would suggest for Nick:  Wes's article points out that you CAN have higher gain in one direction than you have in the other.  Just use resistor values in the chart provided in the 2009 article.  You could have an amp with 15 db in the transmit direction and 24 db in the receive direction.  BTW:  I have been getting a lot of help from Alan W2AEW and Farhan VU2ESE on how to use the NanoVNA to confirm the input and output impedances on solid state amplifiers. 

-- For many years I had the same map of the Moon in my shack.  I hope that map makes it to the new house Nick. 

-- Finally, I was really surprised to hear EI0CL calling CQ during Nick's demo of the receiver.  That is Michael Higgins out in Galway.   Michael was one of my regular contacts when I was out in the Azores.  He is a truly amazing guy.  He is mentioned frequently in my "SolderSmoke -- Global Adventures in Wireless Electronics" book.  TRGHS. 

Hyderabad Field Day

Hams in Hyderabad, India held a Field Day this week.  That looks like a uBITX next to that HT.  FB! 

More info here: 

http://telanganatoday.com/hyderabad-hams-organise-field-day

Adding 10 kHz of Coverage to My BITX 17

 

Solar Cycle 25 is underway.  The Solar Flux Index and Sunspot numbers are up considerably.  I have dusted off my old BITX17 transceiver.  This time around I am using it in conjunction with a waterfall display provided online by NA5B's KiwiSDR receiver, which is located about 9 miles east of me. This SDR receiver allows me to see the entire 17 meter band.   It was this panoramic display that made me pay more attention to the fact that the Variable Crystal Oscillator (VXO) that I am using in this rig prevented me from tuning the lower 10 kHz of the 17 meter phone band (18.110 -- 18.120 MHz). 

I use two crystals switched by a relay to cover the band. One is at 23.149 MHz, the other at 23.166 MHz.  The crystal filter is at 5MHz.  With a coil and some caps I could move the frequencies of the oscillator enough to cover 18.120 to 18.168 MHz (top of the band). 

When I first built this thing, I kind of wrote off the lower 10 kHz of the phone band.  I couldn't get the oscillator to work that low, and I was already satisfied with the top 48 kHz.  But the NA5B waterfall often showed SSB stations in that lower part of the band.  I wanted to talk to them.  So I started thinking about how to do this.       

Looking at my schematic (above) I remembered that most of the frequency lowering was done by L1, a 3.2uH toroid.  I figured that to go a bit lower, I would just have to add inductance.  But I didn't want to lower the frequency provided by BOTH crystals -- I just wanted to bring the frequency with the lower crystal down a bit.  

In my junkbox I found a 1 uH coil.  I disconnected the lower lead of the 23.149 MHz crystal from its connection to the relay.  I soldered the 1 uH coil between the crystal and the relay (see picture above).  This moved the lower limit down to 18.087 MHz. 

Now crystal one provides 18.087 - 18.144 MHz 

         crystal two provides 18.137 - 18.167 MHz

So now I have the whole phone band.  Bob is my uncle. TRGHS. 

This was a very quick and satisfying little fix. As Pete says WYKSYCDS: when you know stuff you can do stuff.  Indeed.  And as I re-build and repair gear that I built years ago, I am often reminded that as time goes by, we learn more. We end up knowing more and being able to do more.   

I am also planning on rebuilding my 17 meter Moxon;  this time I will make it better and stronger.         

N3FJZ's Al Fresco. BITX-inspired, TIA. 50 Watt, SSB Rig (Video)

The last blog postings on Rick N3FJZ were in 2015.  Rick sent me a very uplifting reception report, then we had a pretty amazing Homebrew-to-Homebrew contact.  

Paul Taylor VK3HN yesterday alerted me to a new YouTube video that shows the progress Rick has made with his homebrew SSB rig.   

This is a great example of true amateur SSB construction.  Rick is making use of a combination of digital and analog technology.  He is adapting circuitry developed by others and using it to meet his needs.  During the development stage he is keeping the circuit open (Al Fresco) so that he can easily work on it.  

FB Rick.  

How A Homebrew BITX Comes Together

This is a bit of a blast from the past.  When I was building my BITX17 I paused after placing each stage on the board and took a picture.  Here is the animated GIF.  

BITX on the Beach in East Java (Indonesia)

KC1FSZ's Peppermint III Homebrew BITX with Mods

Hi Guys:

I had some time over the holiday to finish off my second scratch-built rig.  I am very thankful that I got the work done on these projects before I read Pete's "Don't Build It" diatribe.  That would have been very demoralizing. :-)

Scratch build #2 (called Peppermint III) is still fundamentally BITX although I've made changes this time around.   I've switched to ADE-1 mixers with LO ports driven by adjustable gain buffers (ala N6QW LBS).  I've noticed that performance can be improved a lot if you can buffer/tweak the LO levels of the VFO and BFO (particularly carrier suppression on TX).  I did W7ZOI TIAs in the IF chain.  I've also taken the shielding/layout of the finals more seriously and have been able to dial up the power a lot (I did the KB1GMX thing with cutting off the drain pin on the IRF510 and using the tab).  The software is also greatly improved and now supports LSB/USB modes as well as software-driven PTT control for RTTY/FT8 and the hooks for my poor man's panadaptor.  I've been working lots of stations on QRO.

Total build time was about three months (half the time of #1) and the layout came out much smaller than before.  I made a trip over to Williams/Sonoma after Christmas and picked up the 2018 edition of the Peppermint Bark candy tin on discount and I think I can make it all fit.  More to follow ...

Happy New Year and 73s,

Bruce KC1FSZ

KC1FSZ's Above Board, Al Fresco, Free Range, QRO, 4-Foot-Long, Wood-Based BITX

DON'T BOX IT UP BRUCE!  LET THAT RIG LIVE FREE AND BREATHE!  

COULD THIS BE THE WORLD'S BIGGEST BITX?

Hi Guys:

First off, congrats on back-to-back SPRAT covers.  

I’ve succeeded in my QRO quest.  Now I’m running the finals from 28V using a home-brew linear power supply and getting about 20W out.  LM723 + 2N3055’s.  I’m making a lot more contacts too.  The only problem is that the “Peppermint Line” is close to 4 feet long now! (Photo below).  I don’t know how N6QW gets his rigs packed into such small cases.  Putting the various boards in edge-wise will probably help a lot, so that’s going to be my approach to the final packaging job.

73s, 

Bruce KC1FSZ