Modular BITX Boards

https://hackaday.io/project/20067-puzzle-radio-building-blocks

From Mike W0MNE to the BITX20 group: 

Good afternoon,

I've had a few emails regarding the modular BiTX build and I probably should clarify a few things.  First, ON6RF has posted his gerber files on the link at Hackaday.com that I originally posted - just scroll down to around the middle of page to the 'Files' section.  Since he has placed these in the public domain they are available to anyone that cares to download them.  But, because it is HIS work, I'm not comfortable forwarding the files myself.  I don't know if he follows it but I'm sure that he can keep track of how many downloads have occurred and I'm certain he would be gratified to know that his work is appreciated.  What I have offered is to make my gerber file for the motherboard available and, if I can manage it, I will post it here in the files section in the Modular BiTX folder.  I will also include the pdf files that I created for each of the module showing component placement and values.

As for acquiring the circuit boards, as I stated earlier, I use PCBWAY.com for production.  Their prices are excellent and the turn-around time is hard to beat.  The cost of the panelized pc board for me was $5.00 for 10 boards with DHL shipping costs of $22.00 for a total of $27.00.  I ordered the boards late on a Monday and DHL delivered the finished boards the following Monday morning.  Their website says boards that measure 100X100 mm or smaller cost $5.00 for 10 boards so whether you order 1 or 10, the cost is the same.  To complete the build you will need 3 boards to have enough bi-directional amp modules so, if you're interested in following thru with building a modular version, you could perhaps join with two other interested parties and split the cost between you.  With 3 boards you will be able to build a complete transceiver and have 2 extra modules for experimentation for every section except the bi-directional amps.  As an example, on my first prototype I built the double balanced mixer as designed and a second one using an ADE-1 to compare the results.  For the record, there was absolutely no noticeable difference between the two.  I also built a 4-crystal filter as designed and an 8-crystal QER filter on a second board for comparison.  There was a definite difference between these two modules.  

I hope this clears up some of the questions and I'm still available via direct email to answer questions specific to my build or class presentation.  I'm currently working on the assembly manual for my class and when finished I will post it also in the files section.
--73-- Mike  --  W0MNE

https://hackaday.io/project/20067-puzzle-radio-building-blocks

BITX40 Featured in "Nuts and Volts"

Congratulations to Steve Jackson and to "Nuts and Volts" for putting out a very nice article on the BITX40 transceiver.   Steve did a great job in describing the origins of the BITX, and in explaining that Farhan's intent is to encourage experimentation and tinkering.  Pete and I had pitched a similar article to a major ham radio magazine  but sadly they were not interested.  Three cheers for "Nuts and Volts."  I'm thinking about subscribing. 

I know many of you will wince when you see Steve's unshielded mic cord lying right next to the front panel antenna connector, but please don't freak out about this -- in the article you will see that Steve acknowledges that the antenna connector would have been better placed on the back of the box.  That's an example of the educational value of the BITX40 -- live and learn.  Even with the connector like this, Steve was making many contacts. 

The "Nuts and Volts" website very kindly let me read the entire article without a subscription. 

Try here and click on the blue "digital edition" box: 

http://www.nutsvolts.com/magazine/article/meet-the-bitx40-a-single-sideband-transceiver

Or try going directly here:

http://nutsvolts.texterity.com/nutsvolts/201711/?folio=36&pg=36#pg36

Six Stations Worked on BITX Night

I had a a good session with the BITX gang on 7277 kHz starting at  7pm local last night.  Keith N6ORS was on with his MIN-X rig (picture above).  Michael  KN4EAR's signal is much improved (Michael had worked Barcelona with his BITX40 Module earlier in the day). Randy WB5YYM's rig (featured last week on this blog) was booming in from Arkanas.  

LOG: WI1B Ken on BITX, AA4PG Pat, KN4EAR Mike in Falls Church, N6ORS Keith on MIN-X, W1LY Willy,  WB5YYM Randy in Arkansas

More Stations Worked on Sunday Night with the BITXes

I worked AD0RW, AC9PD,  VE3ZBM and WB5YYM on 7277 kHz around 2345 Z Sunday 10 Sept 2017. BITX ops gather on that frequency on Sunday nights at around 7 pm local time. 

The station above is the impressive all HB 40 meter station of WB5YYM.  That's a 49er on the left, and a BITX40 on the right.  The amp in the middle has 2 IRF510s.   HB mic too.   FB

VE1LEB's Ergonomic BITX Enclosure (in Juliano Blue)

Wow, Michael's amazingly cool BITX enclosure looks like you could use it to ask Scottie to beam you up. 
Put an end to those freakish contortions -- 3D print yourself an Ergonomic BITX box! Very FB Michael. Thanks. 

Hi Bill and Pete:

I thought you’d be interested to see my ergonomic enclosure for the BITX40. While operating homebrewed regen radios, I noticed that my hands/arms/shoulders were becoming uncomfortable after a while. After thinking about this for a few days, I realized that the dials on the front of these small radios were forcing my hands into freakish contortions—and having both hands on the dials at all times while tuning made matters worster faster! So I did some homework and determined that our arms and hands most naturally hold things toward each other, as though they are holding a small cylinder by the ends. But the conventional “dials-and-speaker-facing-front” radio case forces us to twist our hands up and outwards from our bodies to twist things. See my blog post http://blog.generaleccentric.net/?p=2009 for illustrations of this problem.

My enclosure design for the BITX40 re-orients the volume and tuning knobs toward the sides of the radio, making their operation much more natural—and pleasant. Although it’s not retro, it does have an unconventional appearance and should fit in quite naturally with all the other homebrewed solutions featured on SolderSmoke. 

You can visit my post at http://blog.generaleccentric.net/?p=2082; the box is available for download and printing at Thingiverse: https://www.thingiverse.com/thing:2508147

By the way, I also have a 3D printable mic for the BITX40: https://www.thingiverse.com/thing:2500483

73, Michael VE1LEB

K.P.S. Kang's Speech Processor and Antenna Tuner for the BITX (and other rigs)

Check out the blog of homebrew wizard K.P.S. Kang.   OM has a nice speech processor based on the LM386.   He also has a very simple antenna tuner and SWR bridge.  FB OM.  

http://smallwonderqrp.blogspot.com/2017/08/two-essential-add-ons-for-bitx-and.html

International Brotherhood and the BITX Rigs

Bore and Heriberto's uBITX board

Nowhere is the International Brotherhood of Electronic Wizards more evident than in the work on the rigs designed by Farhan.  With the BITXs we see rigs designed in India that are now being built and modified all over the planet. Here are just a few examples of the global collaboration currently underway:

In Italy, Giuseppe is putting a BTX40 on 20 meters and making it a dual bander: 

Hi everyone, I just completed some tests on a Bitx40 running in 20 meters band. I addes the 20 as secondary band activate when needed. I apply some mods to switch to secondary QRPLab BPF filter centered to 20 meters and removed the C91 and C92 caps to work in USB. I done some RX tests in the weekend of iaru hf contest to listen some stations Active.
Here the issues registered:
1) the 20 RX sensitivity was a bit weak compared to 40 meters. I need to increase volume. ( To receive the 20 meters the vfo run to 26 MHZ, mybe some stage suffers of poor performance in this High frequency?)
I also tryed to increase the vfo over maximum allowed by raduino, using external buffer, but no results.
Please read the issues as: work but could work better!

2) the RX was not very clean: voice acceptable, but RX of Digital mode not very stable ( probably the cause could be the vfo shift for poor tuning control. I need to add lock function in firmware ...) Or interferences for free wire of connection.

3) Sometimes when switch on or change vfo to other band or mode, the bf amplifier start a self oscillation ...Resulting in my wife's screaming (the tests were also performed during the night!)

No tests was performed at the moment in TX because i need to install the LPF for the new band.
The firmware to make the test was a modified version of 1.17.1, few temporary mods to preset the vfo b to 14 MHz USB and correct the freq. Display.

These my tests.
Giuseppe Callipo IK8YFW.

Pavel is a young fellow in Cuba who is doing great things with the Raduino software: 



Hi to all.

The code was updated, the change log is this:

v1.4Update to catch up with the features added in the Raduino v1.17.1 from Allard's code (CW SPOT and bug fixes)

• Upgraded the operations instructions
  • More user friendly version with embedded images.
  • Add instructions for the S-meter, AGC and TX-power mods details and tricks.
• Moved all images to its own folder "images".

As usual tips/bugs/comments/suggestions are welcomed, you can reach the code here: https://github.com/pavelmc/bitx40/

There is a inoffensive bug in the calibrate process, in which the actual calibrate value is not correctly showed in the LCD until you move the pot to adjust it, I'm working on it.

I'm slowly working in this direction now:

• Bug removal in the calibrate function.
• Finish the upgrade of the Si5351mcu lib with some improvements.
• Adding CAT support via ft857d lib (https://github.com/pavelmc/ft857d):
• Full compliance needs get rid of all the blocking delay() sentences and that need a structural/paradigm code change and a lot of testing (I have Fldigi/MixW/Hamlib to test, I think if that 3 works the rest will do it)
• Moving to a library (yatuli: https://github.com/pavelmc/yatuli) for the pot usage, that will ease the process of implementing the CAT as almost all delay() calls are related to pot/clicks, so I'm on it.
• Maybe implement a multiclick lib to optimize the code and make it more easy to understand.

 Any thoughts or whishes related to that?

I plan to make the CAT operation optional via a #define declaration as not all of us will/want-to use that.
73 Pavel CO7WT

Here we see Bore in Montenegro working on a uBITX designed in Cuba by OM Heriberto

Hi Colleagues

Bore Lezaic from Montenegro is working on the uBitx PCB designed by Heriberto -CM2KMK- from Havana, Cuba

Here some pictures he(Bore Lezaic) have posted in my FB wall.

Any question regarding uBitx PCB please send to Heriberto Gonzalez Mendoza at cl2kmk@frcuba.cu (please take care with the email address it is slight different to his actual call sign).
Qrv's
73's Jc

Bore and Heriberto's Board

Hidehiko in Japan was struggling with some LCD noise in his experimental BITX40.  I passed along the active filter circuit that I'd first seen in Roy Lewallen's Optimized QRP rig. 

To

BITX20@groups.io Jul 29 2017 at 4:22 AM I've finished the Bitx40 experimental project today. I added the AF-AGC and LM386 POP limitter with raduino v1.20.1 (Thanks Allard). And I also added the DuinoVOX for Digital Mode operation. It's a great radio but the problem is only the "LCD noise" when increasing the AF volume. hi... Can I reduce this noise? Or I have to use the analog VFO? Any suggestions welcome.
ja9mat Hidehiko

To Hidehiko JA9MAT: 

Very simple.  Just three parts.   NPN transistor (like a 2N3904) and a 47k resistor (collector to base) 100 uF cap (base to ground).   Vcc the collector. Emitter goes to the DC power input of the AF amplifier.  You can see my use of this circuit in the schematic in this blog post:
Look in the lower right, near the LM386 AF amplifier.  Click on the schematic to enlarge.  73  Bill N2CQR 

My Organic Chip Rig with an LTSpice Schematic

Thanks Bill,
Well I added "3-parts"(2N3904+47kohm+100uF) between the D18(1N4148) and the junction of R111(100ohm) and R1113(220ohm). The noise has absolutely gone!
ja9mat Hidehiko.

_._,_._,_

"So You Want To Build?" Words of Wisdom from Pete Juliano

Everything on Pete's blog is worth reading, but this article was so good that I could not resist posting a link to it here. 

Tribal knowledge from a leader of the homebrew tribe: 

http://n6qw.blogspot.com/2017/08/a-new-line-of-transceivers-difx.html

SolderSmoke Podcast #198 - D-104, HW-8, Juliello, DIFX, Dishal, Baofeng, MAILBAG

Bill Breshears WC3K (SK)

SolderSmoke Podcast #198 is available. 

http://soldersmoke.com/soldersmoke198.mp3

29 July 2017

Sign on a beach store:  SHACK-TACULAR! 

Noticed that EB63 amp was getting hot. Why?  

TT2, Herring Aid5, Farhan's Key:  QRPp and CW!  See?

D-104 lore -- Reading from Bill Breshear's (WC3K) ER article

Astatic  crystal/ceramic element -- disappointingly flimsy

Electret-ing it.  The G-Spot (see picture above)

Walery KB2FIV sent crystal mic element and piezo buzzer (reverse for mic!) FB

HW-8 AF filter Center Frequency Problem.  IT'S TRUE!  Fixed!  Finally. 

Shack re-org at N2CQR

Got Steve Silverman's HP 8640B Sig gen on the bench.  Required reinforcement

Pete's new DIFX

LM373 rigs.  Perhaps with that CA3020 Pete sent me. Chips Ahoy! 

Juliano Yellow? Origins of Blue?  Juliello? Julionyx? 

HB Crystal Filter Capitulation? Don't give up Pete --  just dish the Dishal!

Ceramic VXOs?  K.P.S. Kang

Crystal testers by G7WKE and Dino KL0S.  Impressive. 

Antennas and BITX40 modules.  Antennas are important.

Bill's new Baofeng HT on 440.

Fixing my Sony SW7600GR

MAILBAG

Steve Silverman alerts us to NYC radio row now in the Bronx.

Tony G4WIF on the cover of SPRAT -- Getting the Don Cameron award. FB 

Armand WA1UQO points out that the Berryville hamfest is coming up... 

Thomas KK6AHT F4HDQ writes in. 

On the air with W8NSA

Juliello.  No. 

KC8WBK's Cakepan BITX40

I talked to Paul KC8WBK last night during the regular 7277 kHz Sunday night BITX gathering (7 pm local). I like his BITX enclosure.  Very practical and economical.  It provides ready access to the circuitry.  He also has nice enclosure for the microphone and push-to-talk switch. He has more info on his QRZ.com page. 

K.P.S. Kang's Minimalist VXOs (and one for the BITX)

K.P.S. Kang provides us with some great ideas for simple VXOs.  He includes an intriguing reference for a 5 MHz circuit useable in a BITX.  Tell us more OM! 

http://smallwonderqrp.blogspot.com/2017/07/vxos-simple-minimalists-signal-sources.html

SolderSmoke Podcast #197: Farhan, Fame, 'Fest, Testgear, SSB History, Dishal Dystopia, QRP CW, MAILBAG

SolderSmoke Podcast #197 is available:

http://soldersmoke.com/soldersmoke197.mp3

Up in NYC, met Dave W2DAB. got Steve Silverman's HP 8640B Sig Gen.

Farhan's visit to SolderSmoke HQ

Got me a TEK1401A Spectrum analyzer

Farhan at "Geekfest" @W7ZOI   http://w7zoi.net/Farhan-visit.html

BITX40 Modules.  5,000 already.   1,000 a month.

The BITX pronunciation problem. 

QRP Hall of Fame.  I suspected April 1 reprisal!    "I am unworthy" 

Like in Wayne's World: https://www.youtube.com/watch?v=lBEn3a4TIUw

Dusting off my Tuna Tin 2, Herring Aid 5 and Farhan's key from India.

The Manassas Hamfest:  OLD crystal gear.   20's and 30's stuff. Leon Lambert RX and Philmore Fixed Crystal Detector. 

 Reminder of how YOUNG the radio art is.

RELATED:  Bell System 1953 Transistor Documentary.  11 year old Pete and his CK722.

Bought some good stuff from Charles AI4OT.

Armand WA1UQO gave me a big collection of Electric Radio.  So much history and HB wisdom in there. Frank Jones and Lafayette Radio.  Jim Lamb and 1930s SSB.  

Is the CK-722 the source of Pete Juliano's affinity for Juliano Blue?

Was Wes Hayward already using Juliano Blue?

"Your rig sounds real good for a homebrew rig!" 

"Well, your rig sounds pretty good for a Yaesu!"

Related topic: Going over the Waterfall:  The SDR Superiority Syndrome.  Feathering.

ARRL Arduino Book   by Popiel.    Very nice.  Right level.  Lots of good info.

BENCH REPORT:

Pete's Dishal Dystopia --  Is the perfect TRULY the enemy of the good enough?

Bill's  NE602 RIG: 

Replaced OLED.  Blue one seems noisier.  Shielded it with  copper flashing.

Made me yearn for bigger boxes WITH A HOOD!

DOCUMENTING WITH LTSPICE

MAILBAG:

Special Thanks to our correspondent in the Dayton Xenia Metropolitan area -- Bob Crane W8SX.

Jack Welch, AI4SV 5R8SV -- Our Man in Antanarivo -- Sent me a GREAT BOOK "I, Libertine" by Frederick R. Ewing.   EXCELSIOR!

https://qrz.com/db/5r8sv

Bruce KC1FSZ https://www.qrz.com/db/kc1fsz  Building Scratchbuilt BITX.  On the way put the VFO where the BFO should go and had a DC RX.  FB

Greg, VK1VXG   Suggestion for WA8WDQ on Arduino serial plotter

http://www.instructables.com/id/Ultimate-Guide-to-Adruino-Serial-Plotter/

Ben KC9DLM  Mercury PTO.  In a syringe!   No thanks! Maybe add some high voltage and selenium.  And a radium dial!  Yea!

http://webshed.org/wiki/Mercury_PTO

KY3R's metalized cigar boxes!  FB On Blog.

Richard WB2PEF has revived his Doug DeMaw 8P6 rig.  FB.  But bothered by PTT thump.

Update on Dave AA7EE (from Mike KC6SAX)

AI4OT and N2CQR

N2CQR AND W2DAB

Put Yourself on the BITX Map

On Jun 9, 2017, at 4:53 PM, Doug W wrote:

Seeing the topics for regional operator lists got me thinking.  If words are good, pictures are better.  I set up a google map that you can add yourself too to help visualize where everyone is located.  I was going to add people that responded to the other topics but out of respect for privacy (and my laziness) this should be entirely opt in only.  The map is only accessible with the link below.  The interface is reasonably intuitive but I will do my best to explain how to add yourself.

go to

https://drive.google.com/open?id=1Oa_egVdStSJBF5C7mpS6MXrkces&usp=sharing

type your address in the search bar on the top of the map (the box with the magnifying glass to the right)

hit enter or click the magnifying glass
verify the location displayed
click add to map at the bottom of the box that pops up
now click the pencil/edit icon at the bottom right of the box
change the highlighted address to your call sign and click save at the bottom left of the box
you can also add more information to your spot if you choose to
bookmark the link and check back as more people add themselves

I am making this sound much more complicated than it is.  If anyone can describe the process better please do.

KY3R's Metalized Cigar Box Rig Enclosures

Bill, 

Bob, KY3R, here. Haven't written to you in a few years (although do manage to run into you most years at the Vienna Wireless Society hamfest ). 

Anyway, was watching your visit with Farhan, and you mentioned your penchant for building projects into wooden hobby boxes, and using copper  flashing for shielding. I want to share my solution. 

I snatched up any old cigar boxes I come across. For shielding I use "metal repair tape." This is the stuff used for joining or repairing dryer lint vent ducts, and it is available at any hardware store. Very lightweight, and you just cut the desired lengths, peel off the backing, and press onto the inside of the box. The only drawback is that it is aluminum and doesn't take solder very well, but it is easy enough to add one or two short lengths of wire from the circuit ground plane to a terminal bolted down onto the case interior. 

The attached photos show my current project--a Por Larranaga cigar box in the process of being converted into a home for a BitX-40! I haven't yet fully decided exactly how to position the unit in the box, but as shown in one of the photos, it fits with plenty of room for later mods. As for other decisions, I toyed with the idea of painting or covering the outer box, but I am leasing toward leaving the original cigar box labeling. Arguably adds a bit of "soul," plus who needs a clean panel and all that fancy stenciled lettering anyway. I'll know which knob is which!

73, and as always, thanks to you (and Pete, of course) for your continued work on the SS podcast.

Bob Keller, KY3R

FDIM: W8SX Interviews W8TEE on Facelifts for SSB Rigs

Our intrepid correspondent Bob Crane interviewed FDIM speaker Jack Purdum W8TEE.  Jack made some very intriguing comments on his efforts to enhance the beloved BITX transceiver.  CW! AGC! Speech processing! Woo hoo!  We await more details on how to acquire the board that Jack describes.

Jack is a very accomplished guy who has made many contributions to the radio art, most recently on Arduino microcontroller projects:  https://www.qrz.com/db/W8TEE   

Listen to Bob's interview with Jack here:

http://soldersmoke.com/FDIM17W8TEE.mp3

Thanks Jack! Thanks Bob!

Here are is the manual, bill of materials, and schematic for Jack's board:

http://soldersmoke.com/W8TEEschematic.pdf

http://soldersmoke.com/W8TEEmanual.doc

http://soldersmoke.com/W8TEEbom.doc

Homebrew Peppermint BITX: KC1FSZ Goes Scratch-built and Sweeps a Filter

Hi Bill/Pete:

Congratulations to Bill on the award.  Very well deserved!  

I just watched the video that Bill made with Farhan and I really enjoyed it.  As usual, lots of useful information there.

Farhan’s demo of the Sweeperino was particularly timely because this past weekend I was doing something very similar.  

As I’ve mentioned to Bill before, I am working on a scratch-built BITX to accompany the Peppermint BITX-40 module rig that I’m running right now.  I took Pete’s advice and started from the audio end.  After building the audio amplifier, product detector, and first/last pair of IF amplifiers, I was able to connect the VFO where the BFO is supposed to go and enjoy a pretty reasonable direct conversion receiver.  It works great!!  My first working receiver.

So my next step was the crystal filter.  I puzzled over all of the different articles, tried to follow the G3UUR method, sorted crystals, etc. and finally put the whole thing together.  But all along I’ve had this doubt that I could have possibly followed all of the steps closely enough to achieve the precision needed for a 3.5 KC SSB filter - it just didn’t seem possible.

Last week I decided to try to “sweep” the filter.  This was a multi-day undertaking in itself.  I pieced together the microprocessor, an AD9850, a TIA amplifier, the RF power detector from the SSDRA book, and some software that generates the necessary frequency sweep and collects power readings.  The picture of the test rig is included below.  It’s not much to look at.

With low expectations (and wires that are too long), I ran a few seeps and then downloaded the data onto my computer for analysis.  No fancy software here, I’m just using Excel.  When I put the data into a line chart in Excel, what emerged from the jumble of seemingly random numbers was a thing of beauty: a 3.5 KC passband right below 12 MHz. It’s the next stage beyond the Joy of Oscillation:  The Joy Of Selectivity!

It’s even showing about the right insertion loss.  Note the setup is very primitive and noisy so the fact that I can’t measure anything below -8dB isn’t surprising, you can ignore that part.

But I’m starting to get the feeling that this might actually work.  Onto the diode mixer …

73s,

Bruce KC1FSZ https://www.qrz.com/db/kc1fsz

Video: Farhan in the SolderSmoke Shack! BITX, JBOTS, McDonald Straw Sig Gen, uBITX, Sweperino and more!

Thanks again to Farhan for visiting us.  It was great to see his reaction to my humble implementations of his great designs.  I got him to sign my BITX17.  This was really a fantastic day for me and for my family.

SolderSmoke Podcast #196 Rockets, Pete's EXPULSION, SDR, DiFX, '602 rigs, T.O.M.

View from rocket. I'm in front of the swing-set, with hat on. Billy to my left.

SolderSmoke Podcast #196 is available.
5 May 2017
http://soldersmoke.com/soldersmoke196.mp3

Shenandoah Rocket Launch -- With video!

Pete and the QRPARCI HOF: We thank you for your support! 

Note the strange seasonality of these kinds of events... Always in the Springtime...

April is the cruelest month. Especially the FIRST DAY!  

Feel Tech Follow-up -- the DC blocking cap issue.

HBTV?  Roku Challenge? 

A tube of Desitin?  Why?

SDR Misadventures. 

SDR on a tablet  Just like WA7HRG

Pi Day   More RaspPi Linux observations  TOO HARD

The problem of Si5351 and updated libraries -- old sketches don't work!

My SDR question: If we go with direct sampling, no need for I and Q at front end  No image problem, right?  But why is there often a digital I and Q in the direct sampling receivers?

BITX MODULE

Getting RF in through the DDS jack.

Electric Radio:  Reading from the history of SSB.  And from the T.O.M. article

Joe Carr K4IPV : Homebrew Hero from Falls Church Va.  Any more info on him?

Pete's newest DifX

Pete's new digital scope.

Bill's NE602 RIG, Epiphyte History.

He put AADE crystal filter impedance match circuits in backward  That's why he needed RF amp. Duh.

The perils of a crowded box 

Building RF amp board (BITX Module design) for the NE602 rig.

NE602s do not put out a lot of power. uW

BITX Module Amp circuits very stable.

Chassis as the heat sink.

Mic amp?  We don't need no stinkin' mic amp!  But yes, we do. 741 on the way.

Parts on e-bay very expensive!  Back to the hamfests. On to Manassas!

Congrats to Tony Fishpool G4WIF, who received the Don Cameron, G4STT, Award for an outstanding contribution to low power amateur radio at the RSGB AGM meeting in Cardiff.

MAILBAG

Video (Audio) of N2CQR (me) on 40 Meters with BITX DIGI-TIA

This was the icing on the cake.  Ruben AC2RJ up in New York was monitoring as I called CQ with my BITX Digi-Tia last night on 40 meters.  He recorded the contacts that ensued.  I was really glad that he recorded VE3XBO describing his experiences with a BITX 40 Module at his local radio club -- The WAX Group of the Barrie Radio Club in Ontario. 

Farhan's module is really starting to show up more often on the band. On the 19th of April I talked to Bruce KC1FSZ -- he was on his Peppermint Bark BITX 40.  And on March 30 I talked to Josh KE8CPD on his BITX 40.

Click on the arrow (above) to listen to Ruben's recording.  Ruben has a nice YouTube channel here:
https://www.youtube.com/channel/UCXClX_GBzFQIiqTwgnt8qxA

DiFX! My New NE602 Rig is On the Air

Pete would call this a DiFX:  a transceiver that is Different from a BITX.  This started with my effort to get an Si5351 working with a little 1 inch square OLED screen.  Tom Hall AK2B helped me with the software (thanks Tom). Once I got that done, I figured I could build a simple receiver with a homebrew 11 MHz crystal filter, two NE602 chips, and an LM386 AF amplifier.  That was working great, then Pete told me to turn it into a transceiver.  I used some of Pete's boards (thanks Pete).  

The Epiphyte transceivers also use two NE602's, but they ingeniously switch the BFO and VFO between the two chips.  I didn't switch the oscillators -- instead I switched the inputs and outputs of the two chips using two DPDT relays (thanks Jim).  A third DPDT relay switches the antenna between T and R, and turns on and off the PA stage and the AF amplifier.

This is a DIFX, but there is some BITX circuitry in there.  The power amplifier stages are right out of the BITX Module, as is the AF amplifier (thank again Farhan).

The only real problem I ran into had to do with the very low power out of the NE602 VFO mixer on transmit and the impedance matching between the NE602 and the PA chain.  I had to increase the gain on the first RF amp (pre-driver) using ideas from Steve Weber's 40 meter SSB CW QST contest rig (thanks Steve).  I experimented with various connections between the NE602 and the BP filter.  Finally I got it going.

The heat sink on this one is different too:  it is just the chassis.   The IRF 510 is bolted (insulated) to the aluminum box.

I fired it up this afternoon and in spite of horrible conditions on 40, quickly had a nice rag chew with KJ4ZMV in Indiana.  I haven't even built a mic amp yet!  I am running the D-104 right into the NE602 balance modulator.  There are no signs of unwanted modulation or spurs.

FB!   TRGHS!   VIVE LA DIFFERENCE!