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Showing posts sorted by relevance for query KA4KXX. Sort by date Show all posts
Showing posts sorted by relevance for query KA4KXX. Sort by date Show all posts

Friday, December 13, 2019

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. 

Saturday, January 21, 2023

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: 


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: 



Saturday, July 18, 2020

Overcoming the Complexity of the Michigan Mighty Mite: Walter's Sunrise Net Special


From Walter KA4KXX
June 21, 2020

Michigan Mighty-Mite:  Why So Complicated?

The April 2020 issue of QRP Quarterly magazine featured an article by Bob Rosier K4OCE which included a schematic for a “Ten Minute Transmitter” by G4RAW (SK), which apparently first appeared in SPRAT 82 in 1996. 
It is even simpler than the Michigan Mighty Mite, so this transmitter can truly be built on a solderless breadboard in about 15 minutes, because a complex coil is not required.  
The only tuning needed was for me to establish the correct value of the output series capacitor. 
This rig allowed me to check-in to the Sunrise Net (see details in blue text on my QRZ page) today on my very first attempt, and landed me a 549 signal report from 250 miles away.
The first photo shows the transmitter connected to a Transmit/Receive Switch mounted in an Altoids box. In the Transmit position the antenna is disconnected from my 1979 Heathkit HR-1680 receiver, which then coincidentally supplies a sidetone at an ideal volume level.  That little black pushbutton which can be seen in the second photo serves as my key, and works just fine for a five-minute daily QNI on the Sunrise Net.
Of course, part of the secret is having a crystal exactly on the Net frequency, and I have a few left, free to whomever in the Eastern U.S. is interested in building one of these simple Sunrise Net Special Transmitters and participating in our Net. 


Thursday, December 1, 2022

The 40 Meter Direct Conversion Receiver We Have Been Working On -- Comments Welcome


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: 


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: 




Friday, August 5, 2022

SolderSmoke Podcast #239: Hex DX, VFO Temp Comp, DC RX, Polyakov!, DX-100, Wireless Set, Farhan's "Daylight Again" HDR rig, MAILBAG

N2CQR Hex Beam Aimed at Europe

SolderSmoke #239 is available for download: 

http://soldersmoke.com/soldersmoke239.mp3

TRAVELOGUE: 

James Webb Space Telescope.  Mars returning to opposition in early December.   

BILL'S BENCH

Hex Beam K4KIO - on roof – TV Rotor – 20-17-12  Lots of fun.  Working Japan regularly, Australia, South Africa on long path 17,000 miles.  52 countries SSB since July 11.

VFOs and Temp stabilization.  Dean KK4DAS found my ceramic resonator VFO for DC receiver drifty. He was right.  So I built a real LC Colpitts VFO.  Got me into temp stabilization.  A new hobby!  An obsession.  HT-37 and Ht-32 parts. Ovens?  WU2D’s second VFO video.  Understanding thermal drift and how to address it. Split stator caps.  Cut and try.  

Built a Polyakov DC Receiver. https://soldersmoke.blogspot.com/2010/03/polyakov-plus-dual-band-receiver-with.html  Lauser Plus.  Lauser = Imp or Young Rascal!  DK2RS.  He used a ceramic Resonator VXO at 3.58 MHz.   Mine works great on 40 with VFO running 3.5 -- 3.65 MHz. See schematic below. 

On 40 AM with DX-100 and MMMRX.  DX-100 died.  12BY7 VFO buffer went bad.  How common is failure in this tube type?  Nice QSO with Tim WA1HLR about the DX-100.

Got my Dominican license:  HI7/N2CQR!  SSSS on the way.   Thanks to Radio Club Dominicano and INDOTEL.

Getting more active in the Vienna Wireless Society.  

BOOK REVIEW:  

"The History of the Universe in 21 Stars” by Giles Sparrow.  Written during the pandemic.  Published by Welbeck, in London. https://www.amazon.com/History-Universe-21-Stars-imposters/dp/1787394654  Also:  From “Atoms to Amperes” by F.A. Wilson available for download.  See blog.

SHAMELESS COMMERCE DIVISION:   

Todd K7TFC getting ready to launch “Mostly DIY RF.”   I used his TIA boards in my 1712 rig.  He will have boards like this and much more.  Stay tuned.

I need more viewers on YouTube.  They want 4,000 hours IN A CALENDAR YEAR!  Please watch!

FARHAN’S NEW “DAYLIGHT AGAIN” RIG.  Analog.  VFO.   Comments, observations. We need to get him on the podcast.  Maybe two shows: SDR and HDR. 

PETE'S BENCH

Time very limited. But still sharing lots of tribal wisdom.

Wireless set with tubes!

Tool recommendation – Air compressor

 MAILBAG:

Farhan VU2ESE – Speaking of big antennas “Whenever I look at the huge construction cranes in Hyderabad, I always think how one could make 160m, 4 element yagi using it as a boom..

Todd K7TFC in Spain, spotting Log Periodics in Madrid.

Andreas DL1AJG:  Can Biologists fix Radios?

Janis AB2RA Wireless Girl.  Expert on Hammarlunds.  And was my first contact with the Tuna Tin 2. She too was HB!

Peter Parker VK3YE on Owen Duffy VK1OD

Lex PH2LB on homebrew radio

Would this really be homebrew?  Mail from H-A-D article on FM receiver

F4IET a DSB rig from France

Ciprian got his ticket YO6DXE    

Josh G3MOT sent us a good video about the Vanguard satellite and IGY.

Dave Wilcox K8WPE bought Chuck Penson’s Heathkit book.

Rogier -- So many great articles and links from PA1ZZ

Bill AH6FC  Aloha. Retiring.  Wants to build.  Mahalo!

Grayson KJ7UM  Working on an Si5351.  Gasp.

Mike KE0TPE viewing YouTube while monitoring 6 meters.   He will have a lot of time to watch!

Chris KD4PBJ spotted Don KM4UDX from VWS FB

Mark WB8YMV building a superhet.  Having trouble with 455 kc IF can filter.

Walter KA4KXX Great comment on the Daylight Again rig. 

Ramakrishnan Now VU2JXN was VU3RDD.  Found lost Kindle with SolderSmoke book on it. Building SDR rig from junk box.  Trouble with the LM386. 

Pete, Farhan and Tony:  Shelves of Shame

Daylight Again by Farhan

The Polyakov receiver I built yesterday (from SPRAT 110, 2002!)

Tuesday, March 26, 2024

How to Feel Bad about Carrier Suppression (and How to Get Over It)


Version 2 of the 15-10 rig continues to give me trouble.  But I guess it is "good trouble" because I am learning from it. 

You see, after you build an SSB rig, one of the critical alignment steps is the placement of the carrier oscillator/BFO frequency in relation to the filter passband.  (The IMSAI Guy has a good video on this -- see above.)  You want to place this oscillator somewhere on the downward skirt of the passband curve.  This will add to the carrier suppression already done by your balanced modulator.  There will always be some carrier remaining from the balanced modulator -- putting the oscillator frequency on the downward skirt of the filter passband adds to the suppression the carrier remnant.  

But you can't overdo it.   If you place that carrier oscillator frequency too far down on the skirt, you will start to cutoff the low audio frequencies in your transmit and received signals.  You will notice that your once beautiful sounding receiver suddenly sounds tinny and high pitched.  Yuck. 

So you go back to the books and the websites.  You look at the passband promissed by the Dishal software you used to design the filter.  See below:  

Click on the image for a better view

Surely with a passband as nice as that one, you will be able to find the sweet spot where the carrier is suppressed and your audio remains pristine.  

But I couldn't do this with the 15-10 rig.  I was forced to compromise: I had to accept less than optimal carrier suppression for less than optimal low frequency passband coverage.  And here is why:
Click on the image for a better view

The curve above is a much more realistic picture of what my filter passband actually looks like (see NanoVNA picture below).  The curve above is from the AADE software.  I found out that the Dishal software DOES NOT factor in important things like Q or ESR.  Dishal treats all crystals as "loss-less radiators."  So when you get up to 25 MHz where Q is important, AADE and other programs will show you that your passband has become curved.  And you can see how this curvature makes it difficult to get the kind of carrier suppression and audio response we want.  

What my filter looked like in a Nano VNA
Click for a better view

Look, the rigs work OK.  The receivers sound good to me.  The carrier is so far down that no one can hear it.  I have to remind myself that we are using 'SSB-SC" -- suppressed carrier, not eliminated carrier.  I've worked a lot of DX with these rigs.  But still,  I would like to improve the situation.  It kind of bothers me.  Homebrewers will understand. 

I have been experimenting with different balanced modulators.  I started with the simple two diode, single transformer, singly balanced design from Farhan's BITX20.  It works fine.  But I think I get a bit better suppresson from a doubly balanced diode ring.  I may try an NE602 Gilbert Cell.   I may also try to build a higher Q 25 MHz filter using low-ESR surface mount crystals from Mouser.  Stay tuned.  

Thanks to W7ZOI, VU2ESE, WN2A, KA4KXX, KK4DAS, N6QW, W2AEW, and G3UUR for all the good advice and encouragement.  Please put any additional ideas in the comments below.  

Sunday, December 17, 2017

Building the Ceramic Direct Conversion Receiver Part 2 -- Building the VFO -- Our Goal is JOVO!

DC RX VFO and Buffer

I'll put the full schematic at the bottom of each of the posts so that you can easily refer to the big picture. Above you see the schematic of the VFO circuit. 

OK, here we go. Let's build the oscillator.  Our goal is JOVO -- the Joy Of Variable Oscillations. 

At this point you should have a big-enough copper clad board, and you should have given at least some thought to what kind of enclosure you are going to put the board in when you are done.  It pays to think ahead at least a bit, but don't get so carried away with planning that you never get around to building. 

You should plan the allocation of the space on the board.  Think about where you are going to place each stage.  You can mark out the spaces with a pencil or a Sharpie marker.  You might want to look at my board for ideas:     


In the picture above you can see the four stages.   On the left side of the copper-clad board you can see the Front end: the input filter and the RF amplifier (transistor near the top).  Moving toward the center you can see the mixer stage (around the circular 1k trimmer potentiometer).  Below the mixer (near the big round hole in the Bud Chassis) is the Variable Ceramic Oscillator stage and its buffer amplifier. The right 1/3 of the board is taken up by the audio amplifiers.  Note the use of Manhattan pads throughout.    Click on the picture for a closer look. 


Once you know where you will put the VFO, eyeball the schematic and think about where you will need Manhattan pads.  I often start by thinking of three rectangular pads for each transistor, one for each lead.  You can see that there are a lot of parts hanging off each of the terminals.  I sometimes put a long strip across the top or the middle of the board to carry the DC voltage.  

Since this is an oscillator, you don't have to worry too much about keeping the outputs away from the inputs.  You want this one to take of on you. 

For the feedback capacitors (C16 and C17) and the output capacitor (C19)  , get some ceramic disc NPO caps.  I put a 180 pf cap at C17 only becasue I didn't have a second 150 pf cap in the junkbox.  Either value will probably work. 

You will need a ceramic resonator.  I recommend this one from Mouser.  Again, buy a bunch.  They are cheap: https://www.mouser.com/productdetail/520-zta7.3728mt

You can, to start,  build this circuit WITHOUT the two components that allow you to vary the frequency: without L4 and C5.  Just run the left end of the ceramic resonator to ground. See below.  

Connect a 9V battery to the top of C24.  Without L4 and C5 (with one end of the resonator to ground)  you should be oscillating at around 7.168 MHz (the capacitors in the oscillator circuit are pulling the frequency down from 7.37 MHz).

You need some way to find out if it is oscillating.  If you have an oscilloscope, great.  Put the probe at the output and take a look.  But perhaps a simpler and more satisfying way to do this test is with a radio receiver.  Tune the receiver around 7.168 MHz.  You do not need to connect your receiver to the oscillator.  You should be able to hear it.  If you do, congratulations.  If not, check your work.  Be patient.  This is not plug and play radio! 

Once you get the thing oscillating, it is time to make it variable.  Here is an opportunity for variety and experimentation.  Here are some of the options you have: 


Here is what I found.   The frequency stability of these circuits vary.  But all of them are stable enough.  They might drift a bit so that you have to retune the dial every few minutes.  If that realy bothers you you can upgrade to the air core coil with air variable cap arrangement.  

When I put just a variable capacitor that goes from 17 pf to 159 pf between the ceraamic resonator and ground, I was able to tune the oscillator from 7.220 MHz to 7.420 MHz. 

If I put a fixed 8.18 uH coil between the ceramic resonator to ground that moved the frequency to 7.010 MHz.  You could use a toridal core coil for this, but I had best results with an air core coil.  By putting the 17-159 pf variable cap between the coil and ground (similar to the arrangement shown above) I could tune from 7.010 MHz up to 7.367 MHz. 

You could also replace the variable capacitor with a voltage variable capacitnce diode (aka a varactor or a varicap diode).    I had good results with an MV2301.   

You could try using a cheap little polyvaricon capacitor for C5, but my best results came with an air variable. Walter KA4KXX points out that nice variable capacitors are available here: 
https://www.amplifiedparts.com/products/capacitor-365pf-variable  If you can, get one with a reduction drive to slow the rate of tuning as you turn the shaft.  If you can't get one of these, try to get find a reduction drive to slow down the tuning. 

I ended up using a 3 uH air core coil with a variable cap of around 365 pf this allows me to tune from 7.115 MHz to 7.300 MHz (all of the phone portion of the band) with very good stability -- Juliano Criteria levels of Stability.  

One more idea:   As you build this stage, or right after you finish it, go ahead and build a dulicate circuit, perhaps without the variation components.  Why?  Well that second oscillator might be useful when it comes time to peak and tweak the front end input filter of your receiver.  And that second oscillator can become the start of a second version of this project. 

We talked about this project in SolderSmoke Podcasts #199 #200 and #201

Now I'm going to the beach.  I hope the holiday season bring you all joy -- especially the Joy of Variable Oscillations. Send us reports on your progress, your joy, or your tales of woe. 

The Big Picture

Friday, August 27, 2021

SolderSmoke Podcast #232 -- Mythbuster, Pete's Tube CW Rig, Pete's DC RX and Simple SSB Rig, NanoVNA and TinySA, Very FB Mailbag


SolderSmoke Podcast #232 is available -- Crank it in Robert!


Featuring a guitar intro by Pete "Bluesman" Juliano,  playing his own composition: "Juliano Blues." 

Upcoming GQRP convention and the N6QW rig
Frank Jones and the FMLA -- Possible Victory?
IBEW Stickers:  NASA, Johns Hopkins APL....
Cycle 25 Lookin Better Today:  SFI 93   SN 47
 
Pete's Bench:
Toobular!  A Tube Transmitter
SR-160
Simple SSB rigs around the world! 
KI7NSS's Pacific 40
 
Bill's Bench
The Mythbuster and the Struggle Against the Urban Legend
W2EWL's Cheap and Easy SSB
W4IMP's IMP. Articles in ER by Jim Musgrove K5BZH and Jim Hanlon W8KGI
The Spirit of Homebrew SSB. From Electric Radio K5BZH December 1991
Reduced Front End Gain on the DIGITIA
Back on 17!  HP3SS sells HBR receiver to Joe Walsh
Maybe another Moxon?
 
SHAMELESS COMMERCE DIVISION
 
Test Gear
NanoVNA -- Alan W2AEW helped solve mystery of why NanoVNA not providing accurate readout of circuit impedance.  Over driving.  Need attenuator. 
TinySA -- Limited Resolution Bandwidth.  But you can listen with it!  See video on blog.
 
MAILBAG
-- Google Feedburner to end e-mails from the blog :-(
-- Paul VK3HN -- TIA AGC? Farhan and Paul looking into options 
-- Ciprian's Romanian Mighty Mite
-- Dino KL0S SolderSmoke GIF and graphical presentation on sideband inversion
-- Allison KB1GMX helped me on 24 volts to IRF 510 issue.
-- Dave K8WPE Wabi Sabi and Martha Stewart. And thanks for parts!  40673s!
-- Steve N8NM building a 17 meter rig with 22.1184 crystals in a SuperVXO and a 4 MHz filter.  
-- Dean KK4DAS restoring an old Zenith.  One hand behind your back OM. 
-- Pete Eaton debating SSB or DSB for 17.  Go DSB Pete!
-- Richard KN7FSZ a FB HBer.  Asked about my solid-stating of Galaxy V VFO.  
-- Walter KA4KXX on benefits of no-tune BP filters like Farhan's   FB. 
-- Jack 5B4APL on Time Crystals and Homebrewing in the 4th dimension.  FB OM!  
-- Moses K8TIY listens to the podcast with his young son Robert.  Crank it in Robert! 
-- Farhan and the SBitx on Hack-A-Day
-- Also Tom's receiver from junked satellite rig on Hack-A-Day
-- Todd K7TFC sent in beautiful message about the spirit of homebrewing. On the blog.
-- Grayson KJ7UM was on Ham Radio Workbench with George Zaf
-- AAron K5ATG running a uBitx with a  homebrew tuner and antenna.  Hope I can work him 
-- Heard Mike WA3O last night on 40 DIGITIA.  Water cooled amplifier

Sunday, April 3, 2022

Video of SolderSmoke Podcast #236


SolderSmoke Podcast #236 is available!

Podcast Posted on 1 April 2022:

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. 

Saturday, June 27, 2020

SolderSmoke Podcast #223 Field Day, Club Talks, Patreon, NanoVNA, Farhan Video, SPRAT, BIG MAILBAG



SolderSmoke Podcast 223 is available: 


27 June 2020

Quarantine Field Day!   
Ironically, THIS YEAR we are both participating
Pete's FD Plan, Bill's FD plan 

Talking to Clubs: 
Pete's talk to the Cedar Valley Iowa Club
Bill's talk to the Vienna Wireless Society

Pete's Bench
DDC SDR
Ideas from the Summer SPRAT
Mean Well Voltage Regulator

SHAMELESS COMMERCE DIVISION: PATREON.   SS is an  SV DELOS WANA-BE!
We got our very first Patreon Patron!  Jonathan Magee from the UK!  Upper Left on the blog.
Continue to use our site for your Amazon purchases. 

Bill's Bench
NanoVNA
Understanding L Networks
+/- 6kHz Ceramic filter for Q-31
Lobes, Nulls and WSPR

Miscellaneous: 
Farhan's feedback Amplifier Video
British Antarctic Broadcast heard (sort of)

MAILBAG:
Mauro VA6BRO liked the SolderSmoke book.  Thanks Mauro
Tryg in Galway Ireland is listening.  Hope to get you the signed books Tryg. 
Michael N4MJR suggested that I use N2 Corona Quarantine Radio as my phonetics.  I dunno... 
Ed DD5LP has been helping us get SS rebroadcast on a German SW broadcast station. Stay tuned! 
Rogier PA1ZZ in California sent an e-mail about the Don Lee Broadcast System.  Thanks Rogier!
Rick KE3IJ  Silver Skirt on his 2B also. W3GOO did it.  Rick traded his Commodore 64 for the 2B.  Yea! 
Walter KA4KXX has a simplified circuit for the MMM!  From UK
Peter VE1BZI thank us for the tribal knowledge.  Dipolo Crilolo
Peter VK2EMU Wee need someone to make the Constructor Crusader badge. 
Scott KA9P sent us the Amateur Wireless cover from 1934 with the Constructor Crusader thing. 
John GM4OOU Built lockdown rig.  we want pictures! 
Jerry KI4IO  His version of the Sproutie by AA7EE   FB 
Adam N0ZIB built a MMM
Wouter ZS1KE in South Africa -- comparing notes on Drake 2-Bs
Randall KD5RC wants to get started in HB. 



Friday, April 28, 2023

High-School Students Successfully Avoid THE SHELF OF SHAME -- Update on the Direct Conversion Receiver Project

One of the first finished receivers

Dean KK4DAS, Mike KD4MM, and I had a good day at the local high school yesterday, even after a month of spring break and other absences.  We thought this might have been our last session at the school this year, so we strongly encouraged the students to GET THE RECEIVERS DONE.  We told them about the Shelf of Shame, and warned them not to half-way finish something that would gather dust at the bottom their parents' closet.  They were close to success!  It was time to finish the project. 


We warned them not to be perturbed if the receiver doesn't work the first time they power it up.  This is not "plug and play."  The receiver would likely need some trouble shooting, or at least some peaking and tweaking.  We noted that we often have to sort of coax a signal out of a newly built receiver. 

We soon had the students come forward with two projects that were ready for final testing.  Sure enough we found problems with both.  The solutions provided a lot of educational fun. 

The first group had not yet built the diplexer -- we advised them to skip over the diplexer for the moment -- just connect the output of the mixer to the input of the AF amplifier.  We can't let the perfect be the enemy of the good!  Build the diplexer later, but for now, get the receiver going.  They did, and a few minutes later they were receiving signals from Mike KD4MM's transmitter (on the other side of the lab). 

Then a second group came forward.  We put a San Jian frequency counter on the PTO output.  Uh oh.  Trouble.  Gibberish!  A wonderful troubleshooting session ensued.  With the student, we found that the signal was good at the output of the oscillator transistor, but NOT at the output of the buffer.  At first we suspected that the buffer was bad, but it was not.  Then we lifted the connection to the mixer and suddenly the buffer output was good.  So the problem was in the mixer!  When we disconnected the input transformer of the mixer from the diode ring, THE PROBLEM WAS STILL THERE.  So the problem was clearly in the input transformer.  Dean gave us a replacement transformer.  Soon all was right with the rig, and this group joined the ranks of the successfully completed receivers.   

I think that seeing that two groups had finished helped motivate the others.  Our announcement that successful completion would lead to a "Certificate of Completion" also helped.  But most of all, I think the natural desire to finish the job and avoid the "Shelf of Shame"  was pushing the students forward. 

Other news: 

-- Our stage-by-stage award program continued.  Last time we awarded "The Torry"  for the first successful bandpass filter;  this time we awarded "The Audy" for the first successful audio transformers. 

The Audies

-- We told the students that their work has been entered in a Hack-A-Day contest.  Most of the info and files on the project can be found on the Hack-A-Day site.  Check it out:  

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

-- We also told the students about Walter KA4KXX's very generous offer of a reward for the first students to check into the Florida Sunrise net.  (We had to make it clear that this offer is completely extracurricular and unconnected in any way from the school .)  The students were clearly intrigued.  Sunrise Net may get some new check-ins! 

-- We provided instructions on how to build a simple 1/4 wave reception antenna.  We also did a video.  


We had thought that this would be our last session at the school,  but at the students' request we will be back with them next week for another session.  We think there are at least five more receivers approaching the finish line. 

Monday, September 19, 2022

SolderSmoke Podcast #240 NIMCELS? Hex DX, CBLA RX, PTO? Solid State HT-37? Exotic caps, Benches, SBE-33, TenTec 540, KWM-1 MAILBAG

 

SolderSmoke #240 

Monday September 19, 2022

http://soldersmoke.com/soldersmoke240.mp3

Sorry, I had some technical difficulties so my audio is a bit distorted. 

NIMCELS?  Niche Internet Micro Celebrities. I dunno....  Can our listeners come up with an acronym that describes our place in the universe?  

Sponsors:  Parts Candy.  Carlos in Chicago.  Great leads.  Don't scrimp with a crimp!  You need some good quality test leads on your workbench.   Get yours from Carlos.  Click on the picture on the blog page or go to PartsCandy on e-bay.  

"Techno Wizardry"?   Our lawyers at Dewey Cheatham and Howe will be after them for that!  

Bill's Bench: 

Hex Beam has made me a DXer.  91 countries. Having fun. Mozambique (Long path), San Andres island, and Saudi Arabia, all on Friday. All homebrew SSB 100 watts. 

Put my old 20 meter CW station back on the air:  Barebones superhet and the VXO 6 watter.   WYKSYCDS. This may be one of very few CBLA Receivers in the world!

Been getting active in the Vienna Wireless Society.  Dean KK4DAS is President and a lot is happening in the Club.  Makers group. Lunch with the group on Tuesdays.  Lots of fun.

We are looking at Farhan’s Daylight Again Analog rig.  Using parts from Dean’s 3D printer, we have made PTOs. See blog post for picture.   (But are they really PTOs? Or just Variable Inductors?) 

VFO madness.  Solid stating an HT-37 VFO. Grayson: “You have clearly lost your mind.” Perhaps.  100 MHz FM broadcast RFI. This brought me to capacitors and linear tuning:

SLC, SLW, SLF and Midline/Centerline caps.  Do special caps explain why some VFOs have linear tuning while others do not?  NO, not really.  You can get linear tuning with ordinary caps.  See blog post

Working on the bench.  Reading Adam Savage’s book on workshops and tools. (link to the book in the right hand column of the blog.   Some other workbench links on the blog.  Upgrading tools and test gear.  I have a proper bench power supply. Better side cutters.  Engineering rulers.  Digital calipers. Better solder (I was talking to Ron WA6YOU – a real solder authority - about this.  Kester 60/40 ).

SHAMELESS COMMERCE DIVISION: 


mostlydiyrf.com

Currently offering seven items:

·  UDVBM-1 (in three versions)

·  PG-TIA Broadband IF Amplifier

·  TIA-AGC IF Amplifier

·  Dual-Gate MOSFETs

·  OA741D Op-Amp (discrete components)

·  8-Pole QER Crystal Filter

·  I2C Rotary Encoder

Three more are shown as coming soon:

·  GP Audio Amp (general-purpose audio amp)

·  HyCas IF Amplifier with AGC

·  M-Cubed (Michigan Mighty Mite kit)

·         Mostly DIY RF offers hardware for hardware-defined radio. That's not a comment on software-defined radio. SDR is cool and useful, and it has its place.

·         In fact, I believe in explicitly making use of technology from all eras (vacuum tubes, discrete semiconductors, and integrated circuits

·         What does "mostly" DIY mean? It means making what you want and using ready-made for the rest. Even the most fanatic DIY'ing home brewer does this without much thought. He uses components he didn't fabricate, electricity he didn't generate, and theoretical knowledge he didn't discover. One can't fight all battles, one has to choose which to fight and which to leave to others. If an appliance-operating Ham doesn't want to fight at all, that's okay, but Mostly DIY RF has nothing to offer him.

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

I need YouTube viewing hours.  So I am putting some of the best SolderSmoke podcasts up on the YouTube channel.  Please listen/watch on YouTube. Here is the playlist:  https://www.youtube.com/playlist?list=PLv9MEKq1quk-gnxog7eBqY_y7cpQadf6T   

Google feed no longer sending our e-mails.  So please follow the blog, Get yourself a blog feed reader.  I use Feedly.  It is free.   Download, search in Feedly for SolderSmoke, hit subscribe and you are done. https://feedly.com/i/discover Follow Pete’s blog too!  It is easy.

 Pete’s Bench

Resurrections: 

SBE-33!

TenTEC Model 540

KWM-1

Mailbag:

Dan KC5VPI getting into homebrewing. No longer WRONG!

Michael AG5VG built subharmonic DC receiver, put it on 40 and 20.  FB.

Mike AA9IL working on old tube stuff including a DX-100 AMD UUHF gear up to 122GHz.

Ed WA4MZS liked the SolderSmoke book. USCG vet.  As is Mike Rainey AA1TJ Semper Paratus!

Clint KA7OEI – The Music of the Beams – My Hex  does not sing!  So far!

Walter KA4KXX – The Knack started early.  Video of getting a toolbox for Christmas. And working on PTOs!  He likes them!

Phillip G4HOJ Also working with subharmonic mixers – using the more complex 4 diode version.

Peter GW4ZUA Built an amazing rig from RADCOM (1980s) Cool VFO with varactor fine tuning and a coil with a dust core that was cut in half to minimize temp effect. Box now holds 3  band version of Pete’s SimpleCeiver. FB.

Bruce KC1FSZ building 25 Watt amp for his Peppermint Bark rigs.  We won’t turn him in to the QRP authorities.

Grayson KJ7UM tested the 12BY7A from my DX-100 VFO.  It was in fact weak. Thanks Grayson.

Charles Smith KV4JT has some really interesting stuff on how to solid state tube gear.   Especially R-390s. https://soldersmoke.blogspot.com/2022/08/trigger-warning-solid-stating-old-tube.html

Gianfranco I0ZY Old friend from Rome.  Amplifier manufacturer.  FB.

Paul WA1MAC getting started again after long hiatus.

Vasily.. I mean Todd VE7BPO.  Always great tech info.  Thanks.

Mark WB8YMV building a superhet with a 455 kc IF.

I sent Farhan some comments on his Daylight Again video: He wrote back “I marvel at their stamina to watch an hour long video of a man talking with a funny accent!”  

Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column