SolderSmoke Podcast #229 -- G2NJ Trophy, SDR, HDR, CW! Mailbag

Soldersmoke Podcast #229 is available: 

http://soldersmoke.com/soldersmoke229.mp3

--  G2NJ Trophy is awarded to Pete Juliano, N6QW. 

 -- Get your vaccine shot as soon as you can!  

-- More from "Conquering the Electron" by Derek Cheung. 

-- Bad fire in the chip factory.  Such a shame.  Sad!  I had NOTHING to do with it.  I was home that day.  I can prove it.

 -- Bezos is not such a bad guy.  Turns out he is a space-geek.  

 -- Perseverance was the big space news.  Very cool.  

 

Pete's bench:

Raspberry Pi vs. Microcontrollers

Treedix display

Conversion of the Dentron Scout

CW rigs?

6L6 on a wooden chassis

SHAMELESS COMMERCE DIVISION-  

I NEED TO BUILD UP TIME VIEWERS VIEW MY VIDEOS: So please watch!

https://www.youtube.com/channel/UC20TcdWSSFliMhg3k2A1a5w

--  Our Patreon sponsors get an early look at our YouTube content.  So please, consider

becoming a Patreon sponsor.

--  Please continue to use the Amazon search engine on the blog page (upper right).   

Bill's bench: 

Hodgepodge:   

-- BITX40 Module.  

-- Ramseykit Amp. 

-- San Jian counter,  

-- CW using 750 Hz oscillator. 

-- RF-actuated piezo buzzer.  

-- SDR!  SDR using PC and tablet.  

-- Checking the output with SDR.  

-- Moving the carrier osc frequency.  

 Also, I put the Fish Soup 10 back on the air.  Nice contacts under 200 mw.

Up next:  A rig for 80/75 and 20 meters.  Single Conversion.  Using VFO from a Yaesu FT101 that runs 8.7 – 9.2 Mhz.   Quiz question:  What IF should I use?

MAILBAG

Mark Zelesky sent me wood tokens with power and Ohm's law formulae.  Thanks!

Scott WA9WFA Built a really nice Mate for Mighty Midget RX – getting it going!

Tryg EI7CLB found board of his George Dobbs Ladybird RX.  Rebuild it OM!

Tom WX2J – We talked about “No lids, no kids, no space cadets” nastiness.

Nick M0NTV about sideband inversion.  I like the simple rule about subtraction.

Jonathan M0JGH – Always listen to Pete.  Got married, has mixing product. Leo?

Mike AE0IH.  Dad used a BC-348 in the service. Looking for one.  FB.

Adam N0ZIB – “Silent Shep” site --- with some ham radio shows I had not seen.

Walter KA4KXX in Orlando has a similar subtraction problem with San Jian counter.

Bill N5ALO sent me a really nice KLH speaker.   I’m using it now.

Jason N2NLY – interested in building SSB transceiver.  One step at a time OM…

Trevor in Annapolis sent xcsd cartoon that really hit home. 

Farhan is doing OK in India, diligently protecting his family from the virus.  

Peter VK2EMU also doing well.

Dave AA7EE Casually killed a DC receiver in Hollywood, and disposed of the remains. 

Charlie ZL2CTM doing great things with simple SSB.  Blogpost.

Phil VK8MC in Darwin sends article on "Mend not End" battle against planned obsolescence.

Bob KY3R re my SDR adventures, asked if I’ve had a recent medical/psychiatric evaluation. 

SolderSmoke Podcast #244 PETE IS BACK! TR-7, CK722, BFR106, HP8640B, High-School Receiver, 10 Min TX, MAILBAG

SolderSmoke Podcast #244 Is available:

http://soldersmoke.com/soldersmoke244.mp3

Video version at:

(118) SolderSmoke - YouTube

HE’S BACK! HOORAY! PETE JULIANO N6QW IS BACK! SOLDERSMOKE COMMUNITY WAS SENT INTO A COLLECTIVE FUNK BY PETE’S ABSENCE. ---------------- Pete’s TR-7 (SEE VIDEO ABOVE) CK722 The BFR106

Pete's new blog: https://hamradiogenius.blogspot.com/ ---- Update on the high school project: Mixers made. Harder than they seemed. First QSO with the DC RX. Allan W4AMV Homebrewer TRGHS Ten Minute Transmitter – Better than the MMM! AF4K (SK) crystals. Other supporting projects: Farhan in Hyderabad. Rick N3FJZ, Walter KA4KXX, Andreas DL1AJG Electronics for Biologists. Peter Marks VK3TPM (fighting the siren call of the Si5351) . Steven VK2BLQ built a beautiful one. Daniel VE5DLD will build three of them with his students. Orlando PY2ANE is building one in Brazil. This week: The Bandpass Filter. (Thank you Hans Summers) --- SHAMELESS COMMERCE DIVISION: BECOME A PATRON VIA PATREON. I am posting some fun stuff for the Patrons. AMAZON SHOPPING ADS Now on both the left and right columns. CHECK OUT Mostly DIY RF in the right hand column. ---- My HP8640B Lives to Fight another day. Two new DMMs A low-end Fluke and a AstroAI 6000 Electrolytic Replacement Controversy Continues

Mailbag: -- Dave AA7EE is blogging again! Yea! -- Mike Rainey AA1TJ back in the Hobbit Hole Building a WWVB receiver. -- Farhan is coming to FDIM. -- Tony G4WIF reminds us that 39 bucks for JUST a 60 MHz counter would be great! -- Dave VE3EAC again helped me fix my HP8640B. -- Dean KK4DAS finalizing 10 meter DSB rig. FB. Upgraded my NanoVNA. -- Mike KD4MM giving me a Nano VNA for the SolderSmoke Shack South. -- Ian VK3LA asked what happened to Chuck Adams content. Good question. -- Don ND6T and I have been discussing envelope detection. -- Nick M0NTV working on AM modulators. He has a new video. -- Ciprian YO6DXE built a Ten Minute Transmitter. -- Steve EI5DD Connacht Regional News: https://www.docdroid.net/YJAV800/crnews0223-pdf

Hyderabad DC RX Workshop

Farhan explaining the receiver in Hyderabad

https://soldersmoke.blogspot.com/2023/03/pictures-from-farhans-hyderabad-high.html

SolderSmoke Podcast #224: Mars. Spurs. Bikes. SDR. NanoVNA. Antuino. MAILBAG

SolderSmoke Podcast #224 is available:

http://soldersmoke.com/soldersmoke224.mp3

1 August 2020

--The launch of Perseverance Mars probe with Ingenuity helicopter.

--China’s Tian Wen 1 on its way – radio amateur Daniel Estevez EA4GPZ is listening to it! 

--Sci Fi Books:  Mars Trilogy by Kim Stanley Robinson.  No skip on Mars :-(

--We have some sunspots!  SFI now 72 and the Sunspot number is 23. 

Bill's bench: 

--Conquering Ceramic Spurs in Q-31   Roofing filter -- sort of 

--NE602 for a Q-75 converter – Gilbert Cell. 

--Measuring low power levels out of NE602.  Antuino better than 'scope . 

--NanoVNA   Really cool stuff.  SDR in there. 

--Building a 455 kc LC filter from QF-1 rubble. Using LTSPICE, Elsie... 

--Reviving my bicycle AM radio – The “All Japanese 6”

--Understanding L Network impedance matching. 

--Bill’s new resistor kit from Mouser. Thanks to Drew N7DA. 

SHAMELESS COMMERCE:  PATREON, AMAZON SEARCH.  THANKS

Pete's Bench: 

--Lockdown Special 

--BPF work on SDR Rig

--I U W I H 

Mailbag:

VK3HN Summit Prowler 7

VK2EMU “The Stranger”

SM0P  HB uBITX in Dubai

AE7KI  Worked him in VK from London

ON6UU  EA3GCY’s 4020 rig

KA4KXX A Simpler Mighty Mite

W9KKQ M19 DMR

KD4PBJ Radio Schenectady

W3BBO 12AU7 Regen

KE5HPY Another 12AU7 regen

N5VZH Ne602 Converter

KY3R Wall Art

G4WIF  Spectrum Analyzer in your pocket

W2AEW  Talks to UK Club

KK0S Sent 455 Kc IF cans

KL0S Making 9Mhz filters

VU2ESE  Diving into simple SDR schemes

Dean KK4DAS  Amateur Radio Astronomy

SolderSmoke Podcast #248 -- Back from the Summer -- Spurs and Filters, S-meters, 6BA6 mania, Shirtpocket rigs, MAILBAG

The PsssT Kit, coming soon from Mostly DIY RF

SolderSmoke Podcast #248 is available for download: 

Audio: http://soldersmoke.com/soldersmoke248.mp3

Video: (800) SolderSmoke Podcast #238 -- Spurs and Filters, S-meters, 6BA6 mania, Shirt-pocket rigs, Mailbag - YouTube

Travelogue:  Trip to the Dominican Republic 3-9 August.  Thinking about the M0NTV video on mixers...  

Solder Smoke Shack South is almost done.   I am thinking about workbenches, operating tables and antennas.  How high should an electronics workbench be?   Table height?  Or workbench (woodwork) height?  

My son and I went to see "Oppenheimer"  Trinity test scene very cool.  They wanted to see if the gadget would work! 

Is the SolderSmoke blog completely archived on the WayBack Machine?  Please check and let me know.  Thanks. 

Bill's Bench: 

-- I've been working a lot of DX with the homebrew rigs:  Indonesia, Australia, Japan, Hawaii.  Lots of fun.  15 meters has been especially good. But the rigs still need work: 

-- M0NTV's video got me to put TinySA to work.  I found that output from dual banders could be improved.  Spurs and harmonics. Yuck.  I need more TinySA -- ordered the TinySA Ultra. 

-- Allison KB1GMX helped a lot.  EB63A amp was unstable, especially on 10 meters.  Higher frequencies are harder!  Tightened up shielding, negative feedback, and bypassing.  This all helped, but I found that I needed to take the higher frequency LP filters out of the amplifier box.  W3NQN filters are better, with steeper skirts and better 2nd harmonic rejections. NanoVNA proving very useful. https://www.gqrp.com/Datasheet_W3NQN.pdf

-- Also worked on the Bandpass filters for these rigs.  Farhan's comments on skirts of different filter configurations.  Some are "LSB" filters (with steeper skirt at the highest freq) and some are "USB" filters (with the steeper skirt at the lower frequency)  See diagrams on the blog page. So I built USB new filters for 12 meters and for 10 meters. 

-- Danger that my unshielded wooden box rigs might be inviting feedback.  So I shielded the 1510 rig with copper guitar amp tape (conductive adhesive).  Good stuff.  

-- Phase Noise rears its ugly head again.  See blog posts. 

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

SHAMELESS COMMERCE DIVISION:  

Mostly DIY RF getting ready to release PsssT kits.  Target date:  December 18, 2023 (E Howard Armstrong's birthday).  https://mostlydiyrf.com/

Amazon Search box seems to have died.  I can't get it back.  Can anyone tell me what happened?  (There seems to be "explanations" from Amazon about this, but they are written in a strange language that I cannot follow.)  Something similar happened with the Google Ads on this blog page.  Apparently you can't have ads both on YouTube and blogger.  

But hey, there is Patreon for those who want to support the podcast and blog. 

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

Pete's Bench

An S-meter for Bill? 

6BA6 Mania! 

QRP SSB with 6BA6

Shirtpocket rig re-build

Mailbag: 

Walter KA4KXX has a great article about homebrewing in the September 2023 QCWA Journal.  

 Steve KC1QAY -- Has joined the CBLA.  I sent him a 3579 crystal.  He built a MMM and experienced JOO.  And Allison KB1GMX is in his local radio club.  TRGHS. 

Ajay VU2TGG in Pune, India -- launching a high school receiver effort. 

Denny VU2DGR The Wizard of Kerala: https://soldersmoke.blogspot.com/2023/08/the-wizard-of-kerala-india-denny-vu2dgr.html

Joe VK4BYER working with kids a remote Australian community.  FB. 

Todd K7ZF -- Wants to get into homebrewing. Advised him to start small. 

Dean KK4DAS:  Fixing Hallicrafters Worldwide RX. Ciudad Trujillo!  Got question from Mark in the VWS Makers Group:  HOW DOES Michigan Mighty Mite REALLY Work.  See blog. 

Trevor Woods -- Info on Super Islander Mark IV made in Cuba from old CFL bulbs.  FB. 

Bob KD4EBM sent me some great stuff:  Sony SW receiver,  QCX Mini.  Made a CW contact with the QCX.  Felt virtuous -- it is going to the DR.  Thanks Bob. 

Peter KD2OMV:    One of the guys I worked with the ET-2 transceiver.  Great to hear from him. 

Armand WA1UQO   Richmond area radio museum? https://www.youtube.com/watch?v=BSCmljje1p8

Mike WN2A -- Sent me a great care package with lots of toroids.  A lifetime supply!  Thanks Mike!

Nate KA1MUQ got his Doug DeMaw receiver going after 38 years!  FB.  Been there, done that! 

Tony: G4WIF Liked Valveman video about Gerald Wells.  He visited him! https://soldersmoke.blogspot.com/2023/08/valveman-story-of-gerald-wells.html 

Dean KL7MA  Bill talked to him on 15 SSB.  He had worked Wes W7ZOI!  FB! 

SolderSmoke Podcast 213 WE'RE BACK!

N6QW's Analog CW QRP Transceiver

SolderSmoke Podcast #213 is available. 

http://soldersmoke.com/soldersmoke213.mp3

7 September 2019

The dire consequences of our summer absence. 

50th PODCAST WITH OUR FRIEND PETE! 
THREE CHEERS FOR PETE! 

Pete's Bench Report

-- Transceiver Count:  FORTY!  
-- SDR RADIGS 
-- Colorful OLED screens
-- Pilgrims and Paisanos -- "Left Coast Homebrew SSB"
-- Pete builds a CW transceiver (see picture above)


Bill's Bench Report: 

-- Going minimalist
-- Tuna Tin 2 + Herring Aid 5 = Fish Soup 7 (and later 10)
-- My QRPp QSO with K1PUB overheard in Canada
-- Glen Yingling's ET-1 
-- Bill attempting a single transistor transceiver

SPACE NEWS

-- Antuino's Cubesat Origins. Farhan's Antuino Mods
-- Apollo 11 Anniversary
-- Possibly the best space book ever:  "Carrying the Fire" by Michael Collins
-- Chinese microsat sending eclipse pictures from the moon
-- LightSail 2 success
-- India has spacecraft in lunar orbit. 

Eric Sears ZL2BMI and Dino Papas KL0S on "QSO Today" Podcast

MAILBAG: 

ZL2PD's Sugar Cube VFO
N8WQ gets free samples
N5RWF Getting started, wisely wearing beret
VK2EMU Australian Ad for Collins Filters
W1PJE on new LDMOS PA transistors
KA4KXX Al Fresco 75 meter SSB rig with model plane engine mufflers!  

Forgot to mention:  W9TH still has manuals for whover owns Drake 2-B #4215.  Check your serial number! 

SolderSmoke Podcast #236 -- Bill's 17-12 Rig, Pea Shooter, VFO Wisdom, Temp Compensation, Need Code for Max2870, Making Enclosures, MAILBAG

ARC-5 R-23 Nav Receiver Parts

SolderSmoke Podcast #236 is available!

http://soldersmoke.com/soldersmoke236.mp3

Winterfest!  Many Boatanchors.  Lots of old good analog test gear.  Talk with Dean KK4DAS.  Met up with Armand WA1UQO and Charles AI4OT. 

Pete's Bench: 

-- Looking for help in software development for MAX2870 board.  

-- Tapped Capacitance Impedance Matching

-- The Pea Shooter (See N2USD's version in videos

 below).

-- Tribal Knowledge on Making Enclosures

Bill's Bench: 

-- 17-12 Band Imaging SSB Transceiver.  It works on both bands. 

-- Plan for Glowing Numerals (N6QW has been there and done that!)

-- WU2D's videos on VFOs.  

-- Temperature Compensation:  HT-37 capacitor.  FT-101 VFO,  even in the ARC-5 receiver! 

-- Trying to get more rigorous about receiver design.  Gain distribution, IMD, Dynamic Range, etc. 

-- Do I need a true RMS audio voltmeter?  Or can I get the same info from freeware audio spectrum analyzer and soundcard?

-- 6EA8s replace 6U8s in MMRX 

SHAMELESS COMMERCE DIVISION:   We have a sponsor!  

PARTS CANDY out of Chicago produces quality test leads for your bench.  The guy who runs the company is Carlos, and he is one of us.  He is an electronic tinkerer. See the ad on the left hand column of the SolderSmoke blog.  Just click on the picture of the test leads and you will be taken to Carlos's ebay store.  Go for it. 

Mailbag

Walter KA4KXX in Orlando -- Diodes in BITX Bilats -- Why?  Farhan says To prevent reverse junction of off transistor from conducting and clipping waveform. 

Tony G4WIF -- Audio test gear and G3ROO paraset

Todd K7TFC Pine boards, TIAs and 12 meters

Dean KK4DAS  Ceramic Variable Oscillators on 40.   Juliano Criteria? 

Mike WU2D   VFOs and Temp compensation. ARC-5s

Chris KD4PBJ   A really nice parts care package -- Thanks Chris! 

Steve M0ECS.  Inspired by SS, moved something off the Shelf or Box of Shame. 

Jason KD2RKN Building a DC receiver.  It is all our fault. 

Chris Mannon in Indiana joining the CBLA

KC4GMH is listening! 

Ed N2XDD has been armed with a 3.579 MHz crystal.  

Harvey Wa3EIB working on his museum 

Tim AG4RZ is BACK IN THE SOLDERSMOKE! 

Fred KC5RT -- an old friend -- recommends Bangood RF sig gen for 88 bucks. 

Shlomo 4X4LF listening and homebrewing from a Kibbutz in Israel. 

Chuck KF8TI was a Peace Corps Volunteer in the Philippines. 

SolderSmoke Podcast #214 is FINALLY out!

WE ARE WORKING TO IMPROVE THE AUDIO QUALITY.  IN THE FIRST RELEASE OF THIS PODCAST SOME OF THE AUDIO WAS KIND OF MUFFLED.  I TRIED TO FIX IT THIS MORNING AND I THINK I MADE SOME IMPROVEMENTS.  THE IMPROVED AUDIO IS NOW AT THE LINK BELOW.  

4 November 2019 (shockingly late!)

http://soldersmoke.com/soldersmoke214.mp3

The visit of Farhan to Northern Virginia
"I heard this guy from Southern California on 20..."
Fire Report from Pete

Pete's Bench Report
"When you know stuff, you can do stuff!" 
The CRAP rigs 
Old Boatanchors -- the Swan 120  with SUPER STABLE ANALOG VFO! 
Ten Tec rigs dial cord replaced with Chinese digi sig counter 
Pete's 500 mW encounter with a QRO curmudgeon
The ZL2BMI Challenge has Pete building crystal filters
The Left Coast Loafer CW rig 

Bill's Bench Report

ET-2 Refinements
N0WVA's Regen Receiver 
Going from ET-1 to ET-2
J-310s vice MPF-102
100 mW from a single J-310
Receiver kind of deaf -103 dbm MDS
10 contacts so far in 9 states 
THREE contacts yesterday.
Worked Wisconsin - 633 miles on 92 mW 
We are at sunspot minimum. 
"Rage, rage against the dying of the light." 
Simplicity is the real reason for CW 

IDEA:  Get those Michigan Might Mites on the air! 
Use Reverse Beacon Network to see if you are getting out 
Use SDR receivers to make contacts

MAILBAG
DL1AJG
KC6SAX
W9VNE
KA4KXX
N0WVA
Zl2BMI
AJ6BD  

SolderSmoke Podcast #247 -- Hating on the IC-7300, Pete Goes FT-8 with a KWM-1, Bill's 15-10 Rig, MAILBAG

Bill's 15-10 Rig -- Click on image 

SolderSmoke Podcast #247 is available: 

Audio Podcast:  http://soldersmoke.com/soldersmoke247.mp3

Video:  (482) SolderSmoke 247 -- Hating on the IC-7300, Pete goes FT8 (with a KWM-1), Bill's 15-10 rig, Mailbag - YouTube

Bill’s Bench:

The 15-10 Dual Bander.

n  10 pole crystal filter at 25 MHz.

n  G3UUR, Dishal, AADE and all that..

n  Testing woes.  Looked bad.  But it was a bad test cable. Duh.

n  VFO (Colpitts) at around 3.5 MHz.

n  Buffer blues:  Bad J-310s.  Beware!  

n  Variable cap from a Heath Q Multiplier

n  A bit of a black art – competing goals. Freq coverage, etc.

n  BFO needed an amp to turn on the diodes in the balanced modulator

n  TIA amps.   SIX dual direction TIAs.  18 transistors.

n  On a pine board (like Frank Jones)

n  Will use the N6QW all discrete AF amp.

n  Maybe an RD16 in the final?

n  Will build a second one for the DR.

 Shameless Commerce:  Mostly DIY RF and the PSSST kit.  Todd K7TFC reports:  “The P3ST is on track for Lee Deforest's birthday release (August 26th). I'm going to send out another newsletter on July 4th, and I'll give some details on P3ST development.” Results of Todd’s Survey.

Pete’s Bench

n  FT-8 on the KWM-1!

n  Presentation to the ham club.

n  Why the Icom 7300 is the anti-thesis of homebrew.

MMAILBAG:

-- SPRAT 195  Summer 2023, in the mailbox.  A happy day at N2CQR

-- Armand WA1UQO sent a wonderful book about Faraday and Maxwell… And told me Jim K8OI was heading to our area.  I met Jim at the VWS Field Day event.  FB.  Thanks Armand.

-- Tony G4WIF sent Father’s Day greetings.

-- Alvin N5VZH asking about electrolytics for his 2-B.  Hayseed Hamfest!

-- John AC2RL replacements for the IBEW.  We need to start over!

-- Steve “Snort Rosin” Smith WB6TNL was in the area.  Sorry I missed him.

-- Joh DL6ID helping us to track down origins of a homebrew receiver Grayson saw in Berlin.

-- Grayson KJ7UM was in Europe visiting his wife’s relatives.  But I think he is back in the USA.

-- Walter KA4KXX sent a QRP HB family portrait. 

-- Wouter ZS1KE sent info on surface mount soldering.

-- George Zaff KJ6VU Ham Radio Workbench – re-runs! Recommended audio processor.  Let me know how it sounds. 

-- Michael AA1TJ   Great to hear from him. 

-- Alan Wolke W2AEW on the toroids  he used in Diode Ring video.  Thanks Alan!

-- Dean KK4DAS, AI and SWR meter project  And new lexicon word:  Hamsplaining. 

-- Bob N7SUR --  Let me know we are semifinalists in the Hack-A-Day prize!  

The 15 - 10 rig from above -- Click on image

SolderSmoke Podcast 194 - Approaching the Digital-Analog Singularity

SolderSmoke 194 is available (scroll down for link)
March 4, 2017

BIG NEWS:   uBITX from Farhan

BENCH REPORTS
Pete: Recycling Old Boards
Working on Arduinos and advanced displays

Bill: SDR Adventures and Misadventures.
RTL-SDR is fun.  Built HB front end.  
HDSDR under Windows is fun and easy.
Thought about Raspi3, 7 inch touch screen, Linux, software YUCK.  
Followed advice of Ken G4IIB and got a 50 buck tablet with Google Play. 

Who needs tiny OLEDs?  Use a 7 inch tablet as your display!

Building a Ceramic Resonator for the HRO  455 kc filter
The value of doing something different. 
Boxed up my NE602 OLED rig. 
OLED noise and ACTIVE decoupling.
NE602 and MOSFET tips

LEXICON:  
OTD   Obsessive Tinkering Disorder  G6LBQ
"A Thing of Beauty"  
Source of Tombstoning term:  Don ND6T.
Ken G4IIB’s extremely smooth audio.

ON THE AIR:
On AM on 75 and 40.  Fun.  Old Military Radio Net and "The Lonely Guy Net" on 75 Saturday morning.
Good old 17 meters. Open at mid-day
HB2HB on 40 with W0PWE.
Listening on 60

Hambrew magazines disappeared, but are back now.
EMRFD Classic Edition available
New Posts to BITX HACKS

MAILBAG:
Gloves follow-up. Not a good idea.
VK3YE’s QRP by the Bay event  and a new book!
Colin M1BUU achieves Mountaingoat status
Martin A65DC JoO MMM in the UAE
Tom NY2RF Editorial with mention of JoO!
Lots of Al Fresco rigs: W8LM BITX on a board, Brad WA8WDQ DC RX, KA4KXX Al Fresco OZ DSB
ON6UU DSB from Spain via Belguim
Hugh ZL1UEM SMALL Si5351 OLED
Cookie Tin rigs VK2EMU’s Biscuit Tin DC RX,  WA7HRG’s Popcorn rig
VK4FFAB FB LTSPICE intro
Ken G4IIB’s BITX adventure (with VERY smooth audio.  How smooth? We can’t say.)
VU2XE’s BITX with a CAD box
G0ETP’s shockingly beautiful SDR receiver
Alan W2AEW on the mend with broken ankle.  His videos are a treasure trove of tribal knowledge.

http://soldersmoke.com/soldersmoke194.mp3

Crystals -- Old and New and World War Two

I was watching Greg Charvat's great video about the WWII ARC-5 receiver yesterday. Greg admonished all of us to preserve any WWII gear we might have in our shacks.  Just one day earlier I had found the crystal pictured above in my junk box.   There is some old stuff floating around in here! I will preserve this one. 

Speaking of crystals,  Walter KA4KXX recently sent me some 40 meter crystals for use with my ET-2 transceiver.  Walter suggested that I use them to check into the daily (1300Z) Sunrise Net on 7123 kHz.  These were modern "short" computer crystals.  So I put them into FT-243 and FT-241 holders.  (Don't worry Greg, no WWII gear was destroyed in the process).  It was kind of fun to put the new rocks in old boxes. They work just fine in the ET-2.  Thanks again Walter! 

Finally, Chris KD4PBJ has been helping a buddy of his buy a Drake 2B.   This morning Chris asked about the E Crystal adjustment coil on the back of the Drake.  I told him that was to allow the use of "overtone" crystals.  But, sadly, I advised him not to worry about it too much because the days of ordering bespoke crystals (overtone or otherwise) are behind us. 

A Call for Builders! Please help us Test this Receiver! Please Build this Receiver!

 

This is the Direct Conversion receiver that Dean and I have built.  We plan to have students at a local high school build it, starting in early February.   We would like to have some others build it, to make sure that the design is re-producible without problems.  

Please build this receiver!  But we ask that you build it exactly as per the schematic above and below. Innovation can come later -- for now we just want to make sure this thing works, that there are no errors in the schematic, and that it can be built by the students with minimum woe.  Thanks in advance! 

Dean or others with 3D printers may be able to supply the plastic form for the PTO inductor.  

We know of one other builder, but he is having some trouble.  We would like to confirm that this design is sound.  

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

Above is the screenshot of the LTSpice model of the 40 meter Direct Conversion receiver that Dean KK4DAS and I have been working on.  I will post a larger scale version of the picture below.  Click on the images for a better view.  Comments welcome.  Please let us know if you find any errors or mistakes.  Realize that we wanted to keep this all simple, discrete, and entirely analog. 

Here (I hope!) is the net list for the LTSpice model: 

http://soldersmoke.com/DCRXLTSPICE.net  

First, one of the surprising things about the LTSpice model: IT IS ALIVE!  I never had a VFO or PTO actually turn on for me in LTSpice.  This one did!  So I just connected the PTO to the Mixer and the receiver works in LTSpice.   I just put an RF signal at the receiver input, and you can see the resulting AF across the 8 ohm resistor at the audio amp output.  I was even able to calculate the precise frequency of the PTO:  7078 kHz.  As in the real world, in an effort to stabilize the frequency, I changed the capacitors to NP0 in LTSpice.  Very cool.  Dean joked that all we need is a way to get RF in and audio out and we will have made an SDR receiver.  

About the receiver:  

--  Four stages that will be built by students Manhattan-style on four copper clad boards: Bandpass filter, diode ring mixer, Permeability Tuned Oscillator (PTO),  AF Amplifier.  

-- The bandpass filter is a simple dual-tuned circuit device based on the info on the QRP Labs site.  (Thanks Hans!)  We out a 10k pot as an RF gain control between the antenna and the filter. 

-- The mixer is a standard diode ring.  We included a diplexer at the output using a circuit from the famous W7EL  Optimized transceiver. (Thanks Roy!) 

-- The Permeability Tuned Oscillator is a very simple and very stable Colpitts design developed by Farhan VU2ESE.  We added a simple FET buffer using the circuit in Farhan's Daylight Again rig.  (Thanks Farhan!) 

-- The AF amp is a very simple three transistor amplifier based loosely on designs from Forrest Mims and from the Herring Aid 5 receiver. Both these designs use just two stages -- we added a third and put an AF gain pot between the first and the second stages. There is an impedance mismatch between the diode ring and the AF amp, but we found that most of the proposed solutions were more trouble than they were worth, so we left it as is.  

--Thanks to Wes W7ZOI for his November 1968 QST article on the solid-state DC receiver. Wes's article inspired our efforts.  

Dean and I have both built these receivers.  They work very well.  Dean has even decoded FT-8 with his. We used Radio Marti at 7355 kHz to test for AM breakthrough -- with the diode ring, the diplexer, and the RF gain control we were able to bring the AM breakthrough down to acceptable levels. You can see many videos of my receiver in action over on my YouTube channel:  (355) SolderSmoke - YouTube

Here is a larger image of the schematic (click for a full view): 

And here is a nicer schematic done by our friend Walter KA4KXX: