Listen to Latest SolderSmoke Podcast

Friday, August 7, 2020

Mars: Book Review, Martian Propagation, Martian Moons as VHF Repeater Sites


In SolderSmoke #224 I mentioned the Mars Trilogy by Kim Stanley Robinson.   I found a book review in The New Yorker (see below).   In Red Mars they mention that there is no ionospheric propagation on Mars.  W1PJE and K1RID point out that this is incorrect -- there is ionospheric propagation on Mars.  K1RID provides a link to a really detailed NASA study of this question (it includes discussion of the effect on propagation of Martian dust storms -- good to know!). Finally, 2E0CHK suggests placing VHF repeaters on the two moons of Mars.  I found a good article about the overhead passes of these moons.   See below for all.  

AND REMEMBER: THE ELSER-MATHES CUP REMAINS UNCLAIMED! 


Here's a review from The New Yorker

https://www.newyorker.com/books/page-turner/our-greatest-political-novelist

----------------------------------
Hello Pete and Bill,

Listened to your latest SolderSmoke podcast. Enjoyable as always. But you should correct the record: Mars does have an ionosphere!


The peak daytime electron density ("M2 layer") is low in altitude - perhaps 130+ km, about our E region - and density is like our E region too (5-10x lower than our F region). So for the Mark Watneys carrying their Homebrew rig and inverted V, probably only a few hundred km to the first skip zone. More NVIS flavor than anything else.

Fun to think about. You should go and test it out!

73
Phil W1PJE
-------------------------------------------------

BTW, this made the rounds in our club last year:


dit dit

73 de Ed, K1RID
Newburyport Electronics & Radio Society
www.K1YRD.org


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

Hey Bill,
No skip on Mars ?
No ionosphere ?
Every cloud has a silver lining, even if Mars doesn't have any clouds ;)
Mars has two moons.
Could be paradise for Moon Bounce aficionados. No ionosphere or F layer to get in the way. VHF can get around corners after all.
-----------------------------------
Here is an article describing the overhead passes of the two Martian moons: 

Thursday, August 6, 2020

How to Sweep, Plot, and Measure Filter Output in LTSpice



The other day Pete N6QW posted a very nice graph of a bandpass filter's passband.  He was using LTSpice.  I realized I had a serious gap in my LTSpice knowledge -- I wasn't sure how to do this.

The charming video from India explains how.  Really useful.

Wednesday, August 5, 2020

OSCAR 100 Geosynchronous Satellite Video



I guess the title for this post could also be "How the Other Half Lives."  I'm sure at least a few of you will be thinking about building an OSCAR 100 station after watching this video.  But if you are in North or South America (with the exception of the Eastern tip of Brazil), forget about it.  OSCAR 100 is geostationary over the other side of the planet.  And amateurs have no equivalent on this side of the world.  But we can listen in using the Web SDRs. 

A couple of interesting bits from this recording.  You can hear G7BTP's coming back from the satellite with a bit of a delay -- he is obviously monitoring the downlink when he is transmitting.  DL8FBH says that he doesn't have a receive system of his own -- he is using a WEB SDR station (as I was) for the receiver. 

  

Monday, August 3, 2020

Homebrew Resistor Kit -- Drew's Mouser BOM

I put the resistors in parts envelopes and cardboard boxes

Hi Bill,

You mentioned wanting to get a resistor kit.  If you'd like, I can
help you do what I did.


Then I noodled about it a bit.  And looked at mouser.

A tiny bit of code put together a copy and paste list of part numbers
that I pasted onto mouser's BOM order form.  And bob's your uncle.

In my case, a particular manufacturer's 1/4 W metal film 100 ppm as
they were 1.9c @ 100 pieces.  I created a copy and paste BOM for E6
over 4 decades plus E3 for a 5th and 1M and 49.9 ohms. Less than $2
per value for 29 values.  Not a bad price for the size of the resistor
kit.  I also figured if the value gap was too large, I could fill it
in with the other half of the E12 series.  (E6 series is every other
E12 series value.)

This could be tweaked.  Perhaps fewer resistors in each value.  Or add
some more special values or whatever.

Mouser was kind enough to cut tape and put each value in a flat
plastic baggy with a label as to what was inside.  Sorted in a file
box, it's a snap to grab a resistor.
Perhaps this is something I should post online to share?  Maybe
someone else already has?

On my todo list is to construct my self a homebrew BOM of capacitors.

If you're interested, I could update this and let you know what Mouser
can do for you.  It may not be your preference, but it is an
interesting option.

Best regards,

Drew
n7da

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

Drew:   Your message caused me to think about what I really need in a resistor kit.  I have been using some other resistor kits, but I end up using ALL of certain values and NONE of others.  Your message made me realize that there is valuable data in those old kit packages.  

I took a look a them this morning.   It seems I use the following values:  4.7, 10, 47, 100, 220, 330, 470, 1k,  2,2k, 3,3k, 4,7k, and 10k.  That's about it.  So maybe I just need to go to mouser and order, 50 of each.  I'm thinking 1/4 or maybe 1/2 watt? 

The packaging you describe sounds great.  How can I get Mouser to do that for me?  

I don't think I need the more sophisticated approach you used, but I'm sure we have listeners who could benefit from it. 

Any further suggestions?  

Thanks again,  

73  Bill 
-----------------------------

Hi Bill,

Sounds very good.  It turned out to be simple for me to order a
ridiculously well stocked resistor kit, but doing something custom is
actually a great idea.  If you want both 1/4 and 1/2, get both.  (I
figured I could always make a 1/2 W resistor out of 2 1/4 watt
resistors.)

The packaging is just what they do.  No extra charge other than their
regular shipping and handling.

So, I did this in late 2018.  When ordered, two values were
backordered, but they shipped them out a month or 6 weeks later or
something.  Checking now, 660-MF1/4DC1000F (a 1% 100 ohm metal film
1/4 watt), I see it is out of stock with an ETA of June 1st for 10K
they are ordering.  The other P/N that was backordered was
660-MF1/4DC1503F.  Who knew 100 and 150K ohms were extra popular?
150K is in stock right now BTW.  Maybe it's random what they run out
of?

Best thing is you copy and paste your list of P/Ns and quantity for
each and bam Mouser will tell you pricing and if anything is
backordered, etc.  If you don't like what you see, change your list
and try again.

I actually thought about what I wanted, then looked at Mouser to see
what they had and what the pricing was on it.

So, from this particular resistor family, I see the pricing is what it
was a couple of years ago.

if you order 50 pieces of that 150 or 100 ohm resistor, that is:
50*$0.055 = $2.75 for 50 resistors.

If you order 100 pieces of that 150 or 100 ohm resistor, that is:
100*$0.019 = $1.90

IT"S CHEAPER TO ORDER 100!  Well, at least for this resistor family
and for Mouser's price breaks.  You have to look at the price breaks
versus volume.  And of course, understand the minimum you need and the
maximum you can store in your lab.  :-)  Don't be ordering 10,000.
:-)

So, price breaks for these they show:

Qty.    Unit Price
1    $0.23
10    $0.055
100    $0.019
1,000    $0.014
2,000    $0.009
10,000    $0.008
25,000    $0.007

You can see that there's a good break at 10, 100, and 2,000.  The
quantity with a good break really depends, so you would have to look
at different vendor product families to see.  I don't think I looked
very long.  I probably knew I wanted 1/4 W (may have considered 1/8 or
1/2, don't remember).  I also think I knew I wanted metal film.  When
I saw the pricing on these at 100 pc and with 1% tolerance (so I could
double out to E12 series and have it make sense if it turned out to be
useful for me), I stopped shopping.

Here's the full BOM I ordered.  The top part is some extra parts I
wanted and those couple of special resistor values.  The lower part
was generated by just a few lines of python:

-----
G6K-2F-Y-DC12|8
1N4007FFG|100
1N4448|100
2N3904TAR|100
2N3906TAR|100
2643000101|100
2643002402|25
2673002402|25
2661000101|25
1C10X7R104K100B|50
1C10X7R103K100B|50
ECA-1HM101|25
ECA-1HM100|25
TIP29CG|5
TIP30CG|5
1N5355BG|10
PR01000104700JR500|10
PR01000102200JR500|6
MF1/4DC1800F|20
MF1/4DC2400F|20
MF1/4DC36R5F|10
FC2053-440-A|100
MF1/4DC16R5F|20

MF1/4DC10R0F|100
MF1/4DC15R0F|100
MF1/4DC22R0F|100
MF1/4DC33R0F|100
MF1/4DC47R0F|100
MF1/4DC68R0F|100
MF1/4DC1000F|100
MF1/4DC1500F|100
MF1/4DC2200F|100
MF1/4DC3300F|100
MF1/4DC4700F|100
MF1/4DC6800F|100
MF1/4DC1001F|100
MF1/4DC1501F|100
MF1/4DC2201F|100
MF1/4DC3301F|100
MF1/4DC4701F|100
MF1/4DC6801F|100
MF1/4DC1002F|100
MF1/4DC1502F|100
MF1/4DC2202F|100
MF1/4DC3302F|100
MF1/4DC4702F|100
MF1/4DC6802F|100
MF1/4DC1003F|100
MF1/4DC1503F|100
MF1/4DC2203F|100
MF1/4DC3303F|100
MF1/4DC4703F|100
MF1/4DC6803F|100
MF1/4DC49R9F|100
MF1/4DC1004F|100
-----

So, your BOM (4.7, 10, 47, 100, 220, 330, 470, 1k,  2,2k, 3,3k, 4,7k,
and 10k) would be the following.  Added the 4.7 by hand and deleted
the other values by hand.  Qty 100 each.
-----
MF1/4DC4R700F|100
MF1/4DC10R0F|100
MF1/4DC47R0F|100
MF1/4DC1000F|100
MF1/4DC2200F|100
MF1/4DC3300F|100
MF1/4DC4700F|100
MF1/4DC1001F|100
MF1/4DC2201F|100
MF1/4DC3301F|100
MF1/4DC4701F|100
MF1/4DC1002F|100
-----

Mouser.com.  Services & Tools button.  BOM Tool button.  Login (they
want account for the tools.  I can't complain.)  Upload spreadsheet or
copy and paste.  In this case, copy and paste.  In fact, copy right
out of this draft email and into their tool.  Next.  Then they ask me
for a name for the BOM and if I only want RoHS.  (RoHS is up to you.
I picked only RoHS, because I know all these parts are RoHS and it
won't warn me about lead poisoning or anything.)  Process BOM.
Blammo.

I had the 4.7 wrong, but they figure it out.  Ouch.  Pricey.  Maybe
you don't need so many, but $4.6 for 100.  Parallel a couple of 10
ohm, you'll have less parasitic L in your emitter circuit.  Change the
BOM before you click the add all to cart.  No problem.  Or maybe 4.7
is worth the extra money to a high roller such as yourself.  :-)

2 parts are at 0 inventory.  The 100 we knew about.  470 as well with
6K arriving 15June.  Yes, those ETAs are perhaps questionable.  Dunno.
They will ship you what they have and ship the rest later AT NO EXTRA
CHARGE.  :-)

A third part is at 123 pc inventory.  Act now before they are all out!
:-)  220 ohms.  6K due end of June.

The above would be $25.50 plus less than $10 for their cheapest
shipping option.  Not a bad price for a well stocked CUSTOM kit and
it's really easy to do.  And these are good parts with specifications
and tempcos etc. all in the data sheet.  Sure, you don't need it 99%
of the time, but if you wanted it, because you were doing something
fussy, you have it.

You could cut that price down quite a bit if you went carbon or wider
tolerance.  (Who needs 1%?  This is electrical engineering, not
mechanical engineering!)  Or maybe another manufacturer.  It's easy to
browse on Mouser and figure out those other options quickly and what
it may do to help you out.  Of course, when you get to a price of
$0.00, you still have the flat rate cheapest Mouser shipping as the
floor on what price you can achieve.

Mouser will also give you a print and email with price, part number,
description of everything in your custom kit.  And each pouch is
labelled.  Crazy!  :-)

Another crazy thing is with these BOMs is that you can easily share
them with others.

Best regards,

Drew
n7da

Saturday, August 1, 2020

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



SolderSmoke Podcast #224 is available:


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

Friday, July 31, 2020

D-Lab Re-Caps a Drake 2-B (Very Economically)



A bit ugly, but it gets you there!   I like it. 

Thanks to John KE5ETX for alerting us to this video. 

Tuesday, July 28, 2020

A 75 Meter AM Quarantine Converter for the Q-31 Receiver (video)



A while back Fred KC5RT sent me a nice collection of parts, including some 6 MHz crystals.  I had been thinking of making a converter to put ahead of my Q-31 receiver.  When Fred's 6 MHz rocks arrived, I knew that The Radio Gods Had Spoken (TRGHS).  

I found some NE602 chips in the junk box.   I used an Altoid-sized box for the case.  The toroids are from W8DIZ.  I use trimmer caps from KC5RT to resonate the input and output circuits.  

Hooray!  Now I can listen to 75 Meter AM on the Q-31.  I may have to build a transmitter to go with this contraption.  

Thanks again Fred. 

Monday, July 27, 2020

Paul Taylor's Quarantine "Summit Prowler 7" and some Radio Archaeology



Paul Taylor VK3HN has really outdone himself in this video (above) and blog post. He describes coming across a somewhat mysterious homebrew SSB exciter with some cryptic markings on it. Paul eventually figures them out.  We still don't know who the builder VK3WAC was -- can anyone find him in their logbooks? 

As Paul goes through the description of the transceiver he built around the mystery exciter, he mentions a number of hombew heroes including Farhan VU2ESE, Peter DK7IH, Eamon EI9GQ (I have to get his book!), and Don W6JL.  Also,  our beloved SSDRA book plays a prominent role in the story. 

Paul's video is really beautiful -- at one point the camera pans the landscape and we see kangaroos in the field.  It is also refreshing  -- as we suffer in the heat of the northern hemisphere summer -- to see Paul and his friends out on the summits in their winter coats and hats.  

It looks to me as if Paul built this rig during the current emergency, so I will list it as a Quarantine rig.  Every dark cloud has a silver lining, and Paul's rig has added a bit of silver to the dark COVID cloud.  Thanks Paul. 

https://vk3hn.wordpress.com/2020/07/26/something-old-something-new-a-four-band-5w-50w-ssb-cw-transceiver-summit-prowler-7/

Sunday, July 26, 2020

Alan Wolke W2AEW on IMD, NanoVNA and more (presentation to UK club)



This video is another reminder of how lucky we are to have Alan Wolke W2AEW as a fellow radio amateur, and as a teacher and mentor. 

In this video, Alan is talking to the Denby Dale Amateur Radio Society in Yorkshire, UK. 

The first part of his talk is about IMD products, the importance of 3rd order products, and the benefits of attenuation. 

The second part of the talk (after a few questions) is a look at the NanoVNA, which Alan cites as the "Toy or Tool of the Year."   

I learned a lot from both portions of the presentation.  I now find myself wanting an H4 model of the NanoVNA (bigger screen).  Or maybe even an F model.   Thanks to Alan, I now know what S21 and S11 means. 

Thank you Alan, and thanks to the Denby Dale ARS.  

73  Bill 
  

Saturday, July 25, 2020

ANOTHER 12AU7 REGEN! W3BBO's Quarantine Receiver


Hi Bill,

I was really impressed with Chuck KE5HPY’s 12AU7 Quarantine Regen!  A very nice build and my hat is off to him!  It caught my eye, as I also built a 12AU7 regen during this period, my first “Hollow-State” unit in sometime. 

It would be interesting to find out what other construction projects fellow hams have involved themselves with during this trying time.

Keep melting solder!
73 de Bob W3BBO
  


Friday, July 24, 2020

Radio Schenectady


A while back I posted a picture (see below) of the shortwave dial of an old receiver used by my wife's grandfather.  I noted the odd  presence of 'Schenectady"  among the exotic foreign locations on the dial.  Pete immediately connected the dots by noting that Schenectady was the home of General Electric.  This week Chris Waldrup KD4PBJ sent us a great web site describing the shortwave stations in Schenectady.  Check out the tube that runs 100 kw AM (Big Bertha).  

https://www.radioworld.com/news-and-business/schenectady-shortwave-transmitters-1941

Chris also sent information about BIG AM broadcast band stations: 

In addition to Schenectady being home to  GE it is the city of license to clear channel AM 50 kW WGY 810.  WGY was started by GE so if the radio was GE it was probably a way to promote their station at the time. I heard mention of Rochester too and that would be for 1180 WHAM another 50 kW clear.  Both WGY and WHAM are still there going strong banging out their 50 kW.

And Pete reminded us of KDKA, describing its long-lasting impact on one of his ears:  

Let us not forget KDKA in Pittsburgh at 1020 which I think is no longer clear channel. I used to listen to KDKA on my crystal set when I went to bed at night. My bed had an exposed bed-spring which was my antenna. To this day there is a slight kink in one of my ears where my Brush headphones rested –I am a side sleeper.



Wednesday, July 22, 2020

KE5HPY's 12AU7 Quarantine Regen -- FB!


Bill and Pete:

Thanks for upping the frequency of your podcasts.  Each one is a welcome note to break-up the COVID monotony.

Following on to Bill’s 31m rx, I am pleased to have a new regen on the air and performing well.  This started as the 12AU7 Hartley circuit found on the web; however, the original circuit needed some further work IMO.  I made a number of modifications – outboard 30 MHz LPF (to remove our local Spanish FM station), inductive antenna link, variable cap for antenna coupling adjustment, up to 24V on the plate, extra by-passing, NE5532 audio section vs LM386 and a switched cap for a lower “band”.  It’s still a starved triode oscillator/audio amp and it has that regen presence.  Best DX is Singapore (BBC) and Madagascar although it’s ideal for easy listening on 19-60m to Romania, Greece, Cuban music, Spain, etc.  As Bill said, there is still plenty worth listening to on a homebrew AM rx.  40, 30 and 20m copy OK, but bandspread is tricky! Adjusting regen is good for +/- 1 kHz, kind of a poor man’s BFO adjustment.   I heard a TI station calling CQ on 20m and called him back on my Icom for a QSO. 

By the way, this rx has some serious vintage mojo – Hammarlund varicap, National coil form, Millen dial and an RCA tube.  The all-star team plays great together! It’s a kick seeing the filament glow while putting RF through recycled parts made decades ago.

73,

Chuck
KE5HPY



Tuesday, July 21, 2020

A Quarantine Mighty Mite


'Tis a thing of beauty. 

Bill/Pete:
    I just decided here over the COVID period to head back to basics here and build a Michigan Mighty Mite with a Color burst crystal I had here. And wouldn't you know it, it works!  Here's a couple of pictures, it's not pretty at all. Needs to be mounted on something. 

Don KC9ZMY



Sunday, July 19, 2020

Knack Story -- Tom WX2J

RTTY Model 15

Hello Bill,

Greetings from a fellow ham in Northern Virginia. I have enjoyed the SolderSmoke podcast for a few years now, and I just heard your recent presentation to the Vienna Wireless Society. We have a lot in common so it is about time I reach out to make your acquaintance.

I was born in NYC and grew up in Northern NJ. I was first licensed in 1969 as a high school student (51 years ago! Goodness!). My novice callsign was WN2JFX, and I progressed from Novice and then to General and Advanced as WB2JFX, and then eventually to Extra (in about 1990 -- while the 20 WPM code requirement still existed). At that point I put in for a 2X1 callsign and received WX2J, which is a nice twist on my original call.

I was fanatically active in my early years in ham radio. My Elmer (George, K2VVI, SK) set me up with a DX-40, and my parents provided a brand new Hallicrafters S-120 (you could copy the whole 40 meter band without changing the frequency!). I think I Worked all States as a Novice and learned that the human brain is the most amazing audio filter on the market. When I made General, George lent me an old Hallicrafters SX-25, and then I was really in good shape. Besides CW, I was also very interested in RTTY. I had my own Model 15 leaking oil in the basement and had a blast watching the magic of that thing printing messages out of thin air. I have always been a home-brewer, and one of the first serious things I built was a two- or three-tube RTTY demodulator from the Handbook. Aluminum chassis, chassis punches, tube sockets -- the whole works. I have no idea what the real inductance was of the inductors that went into the filters but somehow if the signals were strong enough, and on 850 Hz shift, it could actually demodulate signals. I probably still have that thing around here somewhere.

Another local ham bequeathed me his entire collection of 73 magazines - 10+ years starting with the first issue (~1960). I read them from cover to cover so many times I probably have them memorized. I became a real fan of Wayne Green, W2NSD, who was always ornery and controversial but a very interesting guy. I met him at a hamfest many years later and we had a great chat.

In any case I wanted to mention some other things that resonate with me as I listen to your podcast. As a kid growing up in the shadow of NYC in those years, you can bet that the Jean Shepherd broadcast was a regular part of our life. My dad used to listen to it every night -- 10:15 p.m. I believe, on WOR -- and we both used to greatly enjoy his stories of lighting up the fuse panel and nearly blowing up the house as he and his old man were playing with radios, etc. It was a common theme in our house too when my ham radio signal would blast into the TV set or I dangled new antenna wires off the house and out of the trees -- "You're going to blow this house up!" I studied electrical engineering in college and was commissioned in the Air Force upon graduation. I served a 20-year career in the Air Force and stayed somewhat active in ham radio. I was licensed and operated out of Okinawa (KA6TF) and England (G5ERE) during tours of duty in the early 1980s. Always an HF guy, in about 1982, in Japan, I bought myself a new Icom IC-720A, and this is still my primary rig. I was an early adopter of PK-232 and did some extensive building and experimenting with it. Sadly though, in the last 25+ years, my ham radio experience has mostly been vicarious as my work and family obligations have just not left much time for ham radio. I do have a G5RV wire antenna strung up but very rarely jump on the air -- sometimes during contests.

In high school we made a field trip to ARRL HQ in Newington, CT. While there we did all the things people do on such a visit, but one of the high points for me was meeting Doug DeMaw. I can just hear how Shepherd would describe it -- "I turned the corner and there he was! In person! The high priest of homebrewing! Doug DeMaw. In the flesh!" Cue the kazoo. I actually also met Shepherd at a book signing (Wanda Hickey's Night of Golden Memories?). I remember presenting him with a computer-printed banner of his callsign -- K2ORS -- produced by one of the few functioning computer programs I had written in high school. I also heard him on the HF bands one night -- I think he was in Florida -- and actually made contact with him, if barely being able to exchange callsigns can count as a contact.

Well, more than you wanted to know. I just wanted to let you know that I enjoy your podcast and can personally relate to very much of what you say. Although I am steeped in Hardware Defined Radio, I am also a software guy so I expect that my future includes SDR. I hope you and Pete are able to continue the podcast for a long time to come because I need the full HDR-SDR spectrum to be covered -- hi.

73,

Tom Fuhrman, WX2J

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. 


Friday, July 17, 2020

SSB Transceivers of the 1960s --- Videos by Mike WU2D



I liked both these videos.  Mike WU2D really does a great job.  He covers a LOT of technology and theory in two videos.  Thanks Mike!  

Wednesday, July 15, 2020

An Attenuator from Fred KC5RT


Fred, KC5RT, sent me an electronics "CARE Package" with lots of really useful stuff, including an attenuator with switches.  All I had to do was find a box and some connectors.  An appropriate box was quickly found in my junk box (TRGHS).  So Fred's attenuator was added to my attenuator arsenal -- thanks to Farhan for getting this started.  

I've already put Fred's attenuator to good use: Instead of building an RF gain control for my Q-31 receiver, I just put the attenuator between the antenna and the receiver.  

Thanks Fred!  


Tuesday, July 14, 2020

ON6UU's DB4020 EA3GCY Rig


Hi,

Recently I got the EA3GCY newsletter,  it announced a new kit DB4020,  a 2 band transceiver kit covering 40 and 20 mtrs.  I know Javier EA3GCY’s kit are good so I ordered one.  A week later it arrived in a brown enveloppe in which I found all components and printboard wrapped in bubblewrap,  it was all well packed and after checking all components all was accounted for,  all components were indeed there.

8 toroids have to be wound,  following the instructions it was piece of cake,  no problem,  

After several hours of work - relax max style - I got everything in place to test,  hurray,  no smoke !!!!  So now the SSB part was ready,  I have 7W on 40 and 3.5W on 20mtr.  Good power for qrp sota,  wff or just garden activity.  A fortnight later I got notice that the CW part of the kit was ready and another week later it arrived here,  I soldered the 2 boards as soon as possible to get a multimode 2 band transceiver.   The 2 boards are the CW interface which also holds the KB-2 keyer,  the second board is the 500-600HZ CW filter.   The KB-2 give the user 4 memories,  beacon function and some more functions.  Good thinking to include the keyer,  it makes life easy when you’re on an activation. 😊   I opted to make the filter switchable,  I like to be able to listen broadband too,  very simple,  cut one leg of the 13 pin connector on the bottom of the CW interface and put a switch on both ends.


After some figgling around I also got the box ready,  a military grade plastic box with wall thickness of 5 mm,  this box should be able to withstand a lot of shocks and a drop to the ground.  I also made a docking station for a laptop battery which holds some 5Ah and which should be able to give me a lot of hours of listening and some 2 to 3 hours of operation.  I had an old laptop which the screen was broken and had some other malfunctions,  I have taken the battery connector out of it,  luckily I still have another laptop which still works and this is the charging station for the batteries …. ..  😊   The docking is only to test,  I will box it up in maybe a some box where I can then maybe also fit a end fed solution or tuner for coax fed antennas.


A new radio also needs a new CW key so I made one out of an old relay,  painted the base green to fit somewhat the box et voila,  here is the result of the complete portable station.



The key can be fitted to the box by means of a bolt and a wingnut.  A short cable goes to the CW connector of the transceiver.

I had a lot of fun constructing this kit,  the box,  the docking and the key.   For 180€ you get a arduino nano controlled CW/SSB transceiver with 2 bands on which most of the activity is and you also get a keyer with memories.   Good deal I think.   More info is available on EA3GCY’s website.  Javier is also very quick in responding to questions,  he ask for opinions and offers almost an Elecraft style of service.

I made some video’s which are on youtube :

The kitters website :

Best 73
Frank
ON6UU




Monday, July 13, 2020

"The All Japanese 6" Receiver


One of the great things about having a "miscellaneous" box in an otherwise well-ordered junk collection is that rummaging through that box will often send you off on fun and interesting radio adventures.  I was rummaging yesterday and I came across the guts of the little AM radio that used to be mounted on my bicycle handle bars.  I last mentioned this in 2011 : 

I was just about to cannibalize this board.  The IF transformers were almost certainly at 455 kc and I could use a few of those.  But then I started thinking and Googling and trying to figure out the circuit.  That all led me this the site that provided the diagram below: 


Six transistors, four transformer cans, two audio transformers.  Yea, that's pretty close to what I was seeing on my board.  So of course I had to see if I could get it going.   I hooked up a 9V battery.  I connected the pot wiper connection directly to the connection at the top of where the pot had been (it had disintegrated).  It works!  It is inhaling nearby WFAX, Falls Church, Virginia. 

You will notice that the transistors in the circuit above are PNP.  I had assumed negative ground and had hooked the battery up accordingly.  No smoke was released and the thing worked, so I guessed that I had assumed NPN correctly.  Sure enough, perhaps aware of the PNP ancestry, the manufacturer had marked my board "BC123 NPN"! 

The author of the book I linked to above dubbed this circuit the "All Japanese 6"  -- an obvious allusion to the All American 5.  

I see real potential in these AJ6s.   A few mods to the front end and you could be shortwave listening, perhaps on 31 meters!   


BTW:  The space on my handlebars formerly occupied by that little AM radio is now taken up by a Bluetooth speaker that plays tunes streamed to my I-phone from Pandora as I make my way down the same old Washington and Old Dominion bike path.  Progress. 



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