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Thursday, December 31, 2015

N8NM's Straight Key Night Rig


Hi Bill,
 
Just wanted to drop you a line to let you know that I’ve recently discovered your SolderSmoke podcasts and am enjoying the heck out of them!  In fact, you and Pete have inspired me to break away from the thermatrons and delve into the wonderful world of the TIA transceiver, and after several weeks of sniffing rosin, my new rig is now receiving signals without the aid of any external life support!  It’s still a bit haywired, but I’m looking forward to pairing it with my little 6AG76L6 transmitter for a few SKN QSOs tomorrow.
 
I haven’t taken any pics of the new rig yet, mainly because, at this point, there’s not much to see, but here’s it’s little octal-based friend with its AD9850/6AG7 hybrid VFO (works a bit better than the VF-1 that it replaced J):
  
Anyway, thanks for putting forth the time and effort to do the podcast!  All the best to you, Pete and your families in the new year.
 
73,
 
Steve Murphy, N8NM

Wednesday, December 30, 2015

The K7DYY Solid State Class D Legal Limit AM Transmitter





I was on 160 Meter AM this morning, talking to Chet WB2AHK in New York City.  Chet had a very strong signal here.  He was running a rig that I hadn't heard about before, a K7DYY transmitter.   See above. Very interesting.   Here are the details:


Chet's receiver was at the opposite end of the technology spectrum -- like me he was listening on a Hammarlund HQ-100.  He told me that he had replaced the old mechanical clock with a digital "glowing numerals" device.  This got me thinking that that space on the front panel might be suitable for a small frequency counter...




Tuesday, December 29, 2015

Alan Wolke W2AEW Interviewed on QSO Today! And it is GREAT!

Picture

A very cool interview indeed.  But how could it be otherwise?  With Eric on one end of the Skype connection and Alan on the other, coolness was inevitable.

In this interview we are reminded of the FACT that Alan has a major case of THE KNACK.  Proof is found in the way he obtained the wire for his first SW antenna:  he unwound the magnet wire in the yoke transformer of a discarded TV set.  THAT, my friends,  is the stuff that KNACK is made of!  

Check it out:


I share Alan's affection for the TEC 465 'scope, but I twitched a bit when he said it is "easy to work on."  It scared the hell out of me!  It features both plug-in transistors and lethally high voltage -- so high that Alan had to lend me a special high voltage probe just to do the measurements.   

Alan's mention of Project Diana and the history of moonbounce reminded me of Ross Bateman, W4AO, the wizard who, in 1952 bounced the first amateur radio signals off the moon.  He did it from the town I live in now, Falls Church, Virginia. Alan provided me with the address from which the signals were launched. 

Thanks Alan! Thanks Eric!  




Monday, December 28, 2015

First Contact on 160 Meters


Hooray!  After 42 years on the ham bands I have finally made a contact on 160 meters.  And it was on AM, using John Zaruba's DX-100.  My antenna is the 185 foot wire that I mentioned in yesterday's post.  I built an L network using a roller inductor and a bread-slicer cap -- the network is at the base of the antenna.  Before dawn this morning I threw my call into a round-table on 1885 kc.  Pete WA1SOV up in Connecticut heard me and we had a short contact. Hooray! 

I hope this puts some pressure on Steve Silverman and Pete Juliano -- they have sworn A SOLEMN OATH to get on top band.  I'm especially worried about Pete's adherence to this pledge -- he seems to be going a bit wobbly on us, playing with Raspberry Pi's and things like that.  C'mon guys!  Top Band awaits!

My antenna needs improvement.  More radials might help. 



Sunday, December 27, 2015

"Receiver Here is My SWR meter OM..."

Santa managed to include in his delivery some of the materials that I needed to build my 160 meter inverted L antenna.   You see, Steve Silverman, Pete Juliano and I have collectively more than 150 years in ham radio, but none of us have ever operated on Top Band.  The three of us have taken A SOLEMN OATH to correct this horrendous deficiency.   I am in the vanguard, partly due to a weather pattern that is perfect for antenna building. 

Armed with a new elastic band for my Wrist-Rocket sling shot and some perfectly shaped lead sinkers,  yesterday -- with the obvious cooperation of The Radio Gods -- I managed to get two ropes over some 70 foot trees.  Soon -- with minimal gnashing of teeth -- I had 185 feet of wire in the air. 

This morning I was messing around with L networks at the base of the antenna.  I took a coffee break, leaving the 185 foot wire and the ground system connected to the coax.   I had the transmitter off, so I was surprised to see the SWR meter jumping around a bit, up significantly from zero.   What could that be?  It wasn't coming from my station, so it had to be coming from some other transmitter. And the slight bit of jumping that I saw on the SWR meter had the familiar pattern of the human voice.  Some radio sleuthing ensued.

I flipped the station antenna switch to the  "bench" position, and connected my scope to the coax.  Wow!  I immediately saw a big strong AM signal with modulation, at about  5 or 6 volts peak to peak.  The Rigol 'scope gave the frequency:  1220 kHz.  

I tuned the HQ-100 to that frequency.  As I listened to Gospel broadcast, I could follow the voice peaks on the 'scope. 

Some Googling ID's the station:  WFAX 1220 AM.   5 kilowatts in the daytime.  1.5 miles from my house.  The vertical portion of the inverted L is obviously picking up a LOT of energy from the WFAX tower.  And the horizontal portion of my antenna is broadside to the WFAX tower.

Of course this all made me think about throwing together a crystal radio, but then I realized I'd already listened to WFAX with simple diode -- the one in my SWR meter.  That little SWR meter was acting like a crystal radio with a visual output!     

Thursday, December 24, 2015

Fessenden AM Broadcast, Christmas Eve 1906? Maybe not....


Garrison Keillor mentioned this in his "Writers Almanac" today. That sent me to Google where I found this: 

http://www.radioworld.com/article/fessenden-world39s-first-broadcaster/15157

But in any case, Merry Christmas to all!

Monday, December 21, 2015

The Secret Life of Machines -- The Radio (Video)



Thanks to Rick N3FJZ for sending this to us.  In 25 minutes these fellows manage to capture and explain much of the "magic" of radio.  Great shots of Marconi, and of Hertz's first rig.  Amazing how they built their own spark transmitter and coherer receiver, launched a kite antenna and sent a signal across the harbor.  Great stuff.  Lots of history.   We've met Mr. Wells before -- he was "jailed for having the Knack!"

Sunday, December 20, 2015

SolderSmoke Podcast #183 Pete's B'day, Simple-Ceivers, Binaural Bliss, 160 or Bust, GOOD BEHAVIOR, MAILBAG

Bill's Frankenstein R2 receives 7 MHz signal and generates I and Q outputs

SolderSmoke Podcast #183 is available. And it is GOOD!

http://soldersmoke.com/soldersmoke183.mp3

20 December 2015

-- Foxes in the Backyard
-- Pete completes another orbit
-- Simple-ceiver Success!
-- Frankenstein Receiver: IT IS ALIVE!  AND BINAURAL!!!
-- 160 Meter AM OR BUST!
-- Fun on 40 AM -- Lots of Multi Elmac AF-67s!  Who knew!
-- The Amateur's Code, and violations thereof.
-- Negative Frequencies? I don't think so.
-- Capacitor Offer from our Secret Benefactor: EXPANDED ELIGIBILITY
-- Projects for 2016: Pete goes Raspberry Pi, Bill goes DX-100
Mailbag:
-- Croation Creation
-- Salvadoran 2B
-- N3FJZ's Homebrew QSL
-- WA7HRG's LBS-ZIA-Simple-Ceiver Mashup Rig
-- KC0IZR turning VCRs into Mighty Mites in NOVA
-- AB1YK Starting with DC RX, going BITX
-- G8GNR puts Mighty Mite on AM!
-- G3ZPF Modulates THE SUN (Amazing)
-- VK3YE's Simple Superhet
-- Grayson in Turkey drools over KG7TR's Octalmania
-- N7REP reaches for the Zantac because of Arduinos and Surface Mount
       

Saturday, December 19, 2015

Mama Mia! Mikele's Croation Simple-ceiver Video



You can just feel the homebrew enthusiasm in this video.  You can almost smell the solder smoke.

We love it when people do videos showing their new rigs spread out on the workbench with individual boards held together by bits of solder.  It is even better when, as in this video, the boards are atop hand-drawn schematic and parts-placement diagrams with much NOODLING in evidence. 

FB Mikele!  And I agree with you about the stations who call "CQ DX-only."  I used to hear that a lot when I was in Europe, and I hear it hear quite a bit too.   I always think it is a contradiction in terms. There were times when I was sitting there with a new rig, anxious to get a signal report from a strong station, and he wouldn't come back to me because of the Continent that I was sitting in! Pity.   His loss.  He might have been interested to hear about the contraption I was testing.  It could have been fun, but no, he preferred to work VK3 or Puerto Rico for the 1000th time. 

Indeed, three cheers for the legendary Pete Juliano!

Thursday, December 17, 2015

Modulated Michigan Mighty Mite?


This suggestion from across the pond is a bit "out there."  In fact, for me it brought to mind the famous line from the Noel Coward song about who goes out in the mid-day sun...  This does seem like an endeavor for our stoic British cousins.  You'll need a very stiff upper lip to AM modulate a Michigan Mighty Mite!  Peter's observation about the "SSB kilowatt nerds" resonated with me and reminded me of the reaction I got when I tried to put a DSB rig on the air in London.   But hey, go for it Peter!   Please let us know the results.   For those who are rock-bound in the CW portion of the band (like 3579) this might be something fun to try using a dummy load -- just to see if you can send an AM  Mighty Mite signal across the shack.

Hi Bill,

Your recent Soldersmoke thoughts re. MMMites have been niggling my imagination; I think radio should be fun, educational, simple and cheap, to encourage young folks to get a license and "appliance users" to melt some solder.

Mike Rainey (AA1TJ) and Jim Kearman (KR1S) have done superb work in reducing RF circuits to a functional minimum... so egged on by a certain Mr. Bill Meara, I'm looking at modulating a MMMite Tx on 80m and building the simple Rx to go with it. I chose 3615kHz as it's a frequency UK VMARS (Vintage Military Amat Rad Soc) use for A.M. - the SSB kilowatt nerds who think the sky will fall down if A.M. corrupts the ionosphere have accepted a few enthusiasts firing a watt or ten of A.M. skywards. I
blame you want to say thanks for setting my mind in this direction.

See how this sounds: modulate a MMM by inserting an electret mic capsule (2 terminal type) between the transistor base and ground,  not forgetting the RF choke from the electret capsule output to the base bias 10k resistor, to avoid the xtal feedback signal being absorbed in the electret...

Yep, that's it: job done, the MMM now produces A.M. as the base current, fed by 10k from the +ve rail in the original MMM, is now partially shunted to ground by the electret capsule. I'll adjust the base bias resistor to get 50% "no speech" carrier and good mod. depth. I'm trying to avoid a mic amp stage; keeps it simple & sweet. If I can get 500mW in total, that's ~ 100mW in each sideband - on a good day with a following wind, on 80m that should go a mile or twenty.

Which leaves a drop dead simple Rx to design - somebody has done similar,
HERE, You got it: an LM386 audio amp as a regen Rx. I had considered the ZN414 TRF Rx, or it's modern equivalents, but they are nowhere near as common as an LM386, or as cheap. IF it works on 80m...! Or, I could try an xtal controlled regen Rx, as per Mike / Jim's designs. Either which way, I'm sure I can find a cheap, simple and effective Rx - but if you know of any.....?

Cheers Bill, TTFN!

Peter Thornton G6NGR

Wednesday, December 16, 2015

A Homebrew QSL Card for a Homebrew to Homebrew Contact


I got a card from Rick N3FJZ today.  FB!   Note the lines for "VFO":  Si5351!   And "Finals": Dual IRF-510s!   Rick wrote that his card is also homebrew!  Thanks Rick.

Tuesday, December 15, 2015

WA7HRG's LBS-ZIA-Simple-Ceiver Project


Wow Pete! 

Thanks for the GREAT info. Can't wait to try things out. One day soon (Christmas is coming) I will have a new computer and can start learning LTSpice.

Great tribal knowledge on the over all gain adjustments as well. And I won't tell the illuminati­čśä.
As for your articles, blogs, tribal knowledge and pot casts with Bill.  Love them. Listen and read everyone. Print and file for later. Mostly because I can't keep up with you on all the great projects.

But in the sprit of home brew and not just stuffing boards or following explicit directions I have built the LBS with my own mods.

1. It's dual band.  Almost. 40&20 LPF and BPF already in. 5watt tx works great but plan on putting in about 40 watts them getting around to making the dual band changes to the sketch and finishing things. I used my own audio amp design. Well not all mine. Manufacture spec sheet and Internet info and LBS. Your preamp, a NTE1288 10 watt audio IC.
Attached are pix of the LBS so far.

The current rig will be 20 meters only for digital modes. It will have a built in audio interface and thinking about including raspberry pi and TFT screen. But that's got to be down the road.
It's a hybrid again. Parts of LBS and ZIA and parts of Simpleceiver. I already had the ZIA IFs built so will have to try the dual FET on the next rig. Modified the audio again. Put in an FET AGC between the preamp and the final IC. About 40 dB dynamic range so should cut down on the vol control twisting when listening to a QSO with one strong and one weak station. So far this build consists of a box of tested modules that have not been hooked together yet. Your FET RF amp will the next board.

Also working on an Arduino Lightning detector with 5115 display. Almost got that one....   Have built couple prices of test equipment. A xtal osc with onboard freq counter and an LCR Transistor tester.

Oh and lets not forget the MMM on 3.58!

I personally know one other ham building a LBS. So don't think your talking into outer space. We are out here listening!  And learning!  And having a great time.

And yes, when I catch up on projects, I'm going to build the actual Simpleceiver.

Thanks again for the fast response. I'll let you know how it turns out.

Jim
WA7HRG






Sunday, December 13, 2015

N3FJZ's New Blog and Impressive Rigs (and a Bandscan!)



Rick N3FJZ and his Lakeside direct conversion receiver bolstered my spirits when I was getting some harshly critical reviews of my signal on 40 meters a while back.  Rick happened to pick me up with his homebrew receiver. The Radio Gods seemed to be trying to balance things out.  There is a LOT of radio mojo in Rick's Lakeside receiver.  Not only does it eschew digital synthesis of the VFO signal, it goes a step further and uses a permeability tuned oscillator -- very cool.  The component and material sourcing adds more luster to the rig.  Rick writes: "A lot of the components used to construct the LS-40 were harvested from discarded consumer electronics I collected back in the 1980's. The base substrate material for the Manhattan style construction, as well as the RF tight enclosure for the PTO, is made from a flattened out tin plated food can. All components are discrete; i.e. no IC's or CPU's."

Rick has launched a blog.  He has some amazing stuff on it.  Be sure to check out his ZX-SSB rig.  Amazingly detailed documentation Rick!  Thanks. 

Find Rick's Blog here:
http://www.remmepark.com/circuit6040/

Saturday, December 12, 2015

YAMMM! Yet Another Michigan Mighty Mite! From KC0ZIR in Northern Virginia


Bill,

Thank you for the podcast and the loads of tribal knowledge from you and Pete! I recently started going through the SolderSmoke backlog, and I am just getting to the Colorburst Liberation Army episodes. I had some crystals for 40m laying around, so I started reading up and winding on a film canister.

Later, I thought I'd hop up the current episode of the podcast while I work, and I heard you guys talk about another push for the Michigan Mighty Mite. I happened to be salvaging bits from an recycling-pile VCR at the time, and I came across this crystal with a familiar label: 3.579545. The radio gods have spoken, so I will be winding a new coil for 80m.

I heard you mention the anonymous benefactor, but I have some aluminum foil, and I plan to brew the cap as well, there are a few options here: http://www.instructables.com/howto/variable+capacitor/

I thought I'd tell you a quick story anyway, because I just want to be a part of the fun. When I was little, our radios all had retractable antennas, and the TVs all had rabbit ears or loops. I would spend nights trying different materials and orientations to try and get better signal. At one point, I ran as much wire as I could in my brother's room (he had a big garage-sale cabinet tv), and we were getting channels from all over the place. We knew when each channel would be showing reruns of Star Trek, so we could catch an episode or two almost every day of the week. We even got some channels that I thought were only available on satellite. I had read in my box of Popular Mechanics magazines that some dish setups re-broadcast their signal on VHF/UHF frequencies with low power, I always suspected that's what we were picking up. 

I didn't know much (or really anything) about the theory behind antennas at the time. I'm still a bit hazy, like with the 75 ohm / 50 ohm cable thing. I thought resistance was a function of length, how can different lengths of coax be the same ohm rating?

Anyway, I just wanted to let you know I'm new to homebrewing, and you guys are a big part of that!
73,
Dan, KC0ZIR
Northern Virginia (a little to the left of you, it sounds like)
..............................

Excellent Dan! 

Getting the 3.579545 MHz rock out of a dead VCR definitely adds mojo to the rig.  Indeed, TRGHS! Thanks for sharing your Knack Story.   I hope to meet up to you, perhaps at the hamfests of Northern Virginia.  In my capacity as Grand Poohbah and Arbiter of Capacitor Eligibility, I hereby deem you  ELIGIBLE for a variable capacitor.   Our secret benefactor will be contacting you.  

73  Bill   



Thursday, December 10, 2015

YS1RS's Salvadoran Tuna Tin and Drake 2B

Roberto YS1RS recently acquired a Drake 2-B and has some minor tech troubles.   I am sure Alan Wolke will come up with the proper diagnosis. (The receiver works fine on the standard bands, but not on the accessory bands.  He can hear the crystal oscillator working fine on the crystal frequencies, but the radio is for some reason deaf on all the accessory bands.)  

Above you can see Roberto's Salvadoran Tuna Tin. 

 Roberto Describes it: "Homebrew: The Tuna Tin 2 QRPp Transmitter (TT2) with 300 mW output power, 14.060 MHz (20 meters band), Crystal controlled, 13 Volts, CW-Only. As its name implies, its main chassis is a Tuna Tin Can.  In our case, it is a delicious and exotic Salvadorian made tuna in chunks, topped with Jalape├▒o Chile. "

Check out Roberto's QRZ.com page:

Roberto has an amazing collection of gear, much of it thermatron, some of it homebrew.  And he has only been on the air five years.  He is a true member of the International Brotherhood of Electronic Wizards.  His work takes him to some of the most difficult places in the world.  FB Roberto! 




Wednesday, December 9, 2015

W7YRV: 197 feet up, on a Homebrew Tower

I talked to  Roy W7YRV on 40 SSB last night.   He was running a homebrew linear.  His blog has a lot of information on his truly massive desert antenna system.

http://w7yrv.blogspot.com/

Tuesday, December 8, 2015

Jean Shepherd's call signs, a QSL card, and much more


I was listening to 160 meter AM yesterday  afternoon when I heard a familiar call:  K2ORS.   I knew that someone else had picked up Jean Shepherd's last callsign, so I knew that I was not listening to a CQ from the great beyond.   Turns out that K2ORS is now OM Warren Ziegler up in Massachussets. Warren is active on HF and 160 and also works with experimental low frequency transmitters.  He is a big fan of Shep.  I think Shep would be pleased that someone who melts solder has his old call.

Searching for Warren on QRZ.com led me to a site with an amazing amount of info about Shep, his callsigns, and his early days in ham radio:


We talk about Shep quite a bit on this blog.  Here are all the Shep blog posts:


Shep said that when, as a teenager, he got his ham radio license, he was so proud that he went around thinking of himseld as "W9QWN, a man of substance."  Indeed he was.

EXCELSIOR!

  

Monday, December 7, 2015

Daytime Occultation of Venus TODAY! LUNCHTIME (on East Coast)



Thanks to my Michael EI0CL for alerting us to this.  It will happen today, very conveniently at lunchtime on the East Coast of North America.  I may have to bring my Soviet binoculars to work.

Details here:  http://spaceweather.com/

It has already been a nice day for astronomy here in the wilds of Northern Virgina.  National Public Radio on Sunday alerted me to the fact that Mars is high in the pre-dawn sky.  Our friend Armand e-mailed alerting me to possible clear skies this morning.  The leaves are down and no longer obstructing my view of the Southern sky.  With my six inch telescope I got a very nice view of Jupiter and the four Galilean moons.  We are pretty far away from Mars at this point, so I could see no surface feaures, but it is always nice to see that distinctively red disk. And Venus is poised to disappear behind the moon.  

Good luck with Venus and the Moon.  Please send in reports. 

And speaking of occultations, check this one out (thanks to Farhan for the alert):


The moon passed between Nasa's Deep Space Climate Observatory and the Earth, allowing the satellite to capture this rare image of the moon's far side in full sunlight. We normally don't see this side of the moon. As the moon is tidally locked to the earth and doesn't rotate, we only ever see the one face from the earth. Awesome shot!

Sunday, December 6, 2015

New Rig: The FRANKENSTEIN Phasing Receiver

Here is my latest project.  I call it The Frankenstein because of the two BNC connectors that come off the side of the DDS oscillator box -- they look to me like the bolts on Frankenstein's neck. The square waves from the DDS LO also seemed to evoke Frank's bolts. There may be other similarities.  We'll see.

Here is the idea:  Phasing,  Direct Conversion, Image Rejecting receiver based largely on the R2 design by Rick Campbell KK7B  as presented in the January 1993 QST.

I'm using an AD9850 with an M0XPD Kanga board and an Arduino to generate the quadrature LO signals (you can see the square waves on the 'scope in the background).  I'm using the software of Richard AD7C;  this, combined with the divide-by-4 scheme on the Kanga board,  puts the upper limit of reception at 7.3 MHz.  That's OK for now. 

When I first fired up my AD9850 box I was dismayed to find that the square wave quadrature output was no longer there.  I was about to give up and get anther shield board, but this kind of surrender bothered me.  So I started troubleshooting and isolated the problem to the /4 chips. My soldering of the surface mount chips was, well, a bit dodgy, so I changed to a tiny soldering tip and reheated all those tiny little pads.  Hooray!  I fixed it. 

The receiver will be built mostly on a PC board that Pete made for me back when he was trying to convince me to build a fourth BITX receiver.  I am pleased to put the board to use.   See below.

Yesterday I soldered on the two SBL-1 mixers that will form the heart of this receiver.   I realized that the very robust quadrature square waves from the Kanga board might be robust enough to fry the sensitive little SBL-1s.  Sure enough, I measured about 17 dbm coming out of the Kanga board.   I threw together two roughly 10 db resistive pads.  These should prevent the SBL-1s from releasing their smoke.     

I hope this receiver will be four receivers in one:

1) Standard DC receiver.

2) Binaural Receiver!  Groovy, stereo CW that floats around in your head,  man! 

3) I-Q receiver that can be fed into the sound card of the computer for DSP, panoramic display, etc.   I promise not use it to find fault with the signals of homebrew SSB rigs.

4) SSB image rejecting receiver for easy, Direct Conversion SSB listening without the burden of having to listen to the other side of zero beat. 

There is already a lot of soul in this new machine:  Kanga board with the design my Paul M0XPD, PC board made on Pete's $250,000 CNC machine, and all of it on an actual breadboard (from Italy, I think).  

Rick Campbell and Peter Parker have commented on the allure of phasing rigs.  There is something very attractive about them.  There is a cleverness in the way this design exploits the phase relationships between sidebands to allow us to null out the unwanted side of zero beat.  It took me a while to really understand how this is done -- once I understood it, I really wanted to build a rig that would make use of this principle.    





Saturday, December 5, 2015

Alan W2AEW Hears me on 40 AM with his Drake 2B




Alan W2AEW writes: 

How appropriate! I was casually listening to 40m AM on my refurbished Drake 2B, and I hear the rotation get passed along to none-other than N2CQR - the man that got me excited about the 2B in the first place. FB 20 over signal in NJ, OM! I was able to grab the video camera quickly before you signed off.  Alan's video appears above.

73,
Alan W2AEW
Holy cow Alan,  THE RADIO GODS HAVE SPOKEN!  Clearly you need to get on 40 meter AM.  Maybe get a DX-60 or something.   In your video I spotted several items in your shack that are also in mine:  in addition to the 2B, I see  a Turner +2 transistorized microphone, and that little (very useful) RadioShack speaker. Glad you heard me OM -- thanks for the recording!
73 Bill

Friday, December 4, 2015

The Pleasures of AM, and The 807 (Truly a Bottle Worthy of the Gods)

Sometimes a message posted in the comments section of the blog is so good that it needs to be raised up and converted into a posting all its own.  Such is the case with a message that Rupert G6HVY sent us last month about AM and old rigs.  60 meters eh? Hmmm...

Rupert wrote:

It's always a pleasure to listen to AM QSOs, which hereabouts seem to be mostly on 80 and 60. I bought an FM board for my FT-101ZD with the intention of getting some 10m action, but now I think I'll leave the AM board in (you can't have both) for when I get the beast out of storage. AM, even AM that hasn't been optimised for beautiful audio, sounds so much nicer than SSB.

The other side of AM is to get old military rigs up and running, which is quite the opposite to the golden voice crowd. Another project waiting for time and energy here is an RCA-built Wireless Sets Number 19, which can put out ten watts or so of AM from its 807 (truly a bottle worthy of the gods) - and of course, there are infinite numbers of 50s and 60s vintage thermionic projects in the contemporary magazines. It would be particularly satisfying to find the original PSU for that, as it has two Dynamotors to convert the 24V DC supply to HT, with the transmitter one cutting in when the PTT (sorry, pressel switch) is hit. I say cutting, it actually runs up to speed over a couple of seconds, giving an original 19 Set a very distinctive slow fade-in at the start of an over. Hearing one of those crackling away on 5 MHz is utterly delicious.

Rupert, G6HVY

Thursday, December 3, 2015

Pete Juliano's Simple-Ceiver on Hack-A-Day Today!


Check it out!  Pete's awesome project -- and equally awesome documentation of the project -- is recognized this morning by Hack-A-Day! Congrats Pete!  

http://hackaday.com/2015/12/03/radio-receiver-build-log-and-more/ 

Wednesday, December 2, 2015

Colchester Mighty Mite


GM Bill,

So, I got round to making my Michigan Mighty Mite!

The crystal arrived almost safe and sound, thanks to the USPS’ mail crusher. Perhaps they think that because email and packets can be compressed they can do the same with parcels? (the photo really doesn’t do it justice - the orange area is a large dent…):


No 2 son, Cameron (12), got involved - The extremely neat tank coil is his handywork :


And so to the video: Not only does it oscillate on the correct frequency as shown here, it also has the added bonuses of oscillating around 21.5Mhz (which is the number my frequency counter gives - which caused a great deal of head-scratching on first smoke), and muting the FM broadcast receiver on 96.1MHz on the shelf 3 feet away!. The dummy load is the 3w metal film resistor suspended in mid air.


You might notice more resistors in the circuit itself than the diagram calls for. I chose to have 2 x  20K resistors in parallel to produce a single 10K resistance that could handle .6W. And the poor old 27R .3W resistor got really hot and discoloured before rapidly increasing its resistance ( !! ), so I used 4 (2 serial pairs in parallel) to handle the current. They still get hot, but survive. And the 2N2222a has a bulldog clip heatsink.

Please excuse the uncorrected error at the end of the CQ call!!

This is the second transmitter I have ever built - the other one is a 30m Hans Summers QRSS kit which you also get the ‘blame’ for :-)

Thank-you, Bill. Keep up the good work.

73’s de G7TAT, Colchester, England.







Tuesday, December 1, 2015

Pete's Simpleceiver is DONE! And it is a thing of beauty


Pete's Simpleceiver is a thing of beauty.  And it is done.  And people are already building it: Jim WA7HRG has one in the works.  Go to Pete's blog for more details, pictures, videos, LTSpice simulations etc.  http://n6qw.blogspot.com/  Congrats Pete! 



Sunday, November 29, 2015

A Very Unusual Explanation of AM and SSB -- What Do You Think?

Wow, I've never seen it presented this way.  Am I losing it or is this just completely wrong?   This comes from this web site:

http://www.dsprelated.com/showarticle/176.php


TRANSMITTED SSB SIGNALS
Before we illustrate SSB demodulation, it's useful to quickly review the nature of standard double-sideband amplitude modulation (AM) commercial broadcast transmissions that your car radio is designed to receive. In standard AM communication systems, an analog real-valued baseband input signal may have a spectral magnitude, for example, like that shown in Figure 2(a). Such a signal might well be a 4 kHz-wide audio output of a microphone having no spectral energy at DC (zero Hz). This baseband audio signal is multiplied, in the time domain, by a pure-tone carrier to generate what's called the modulated signal whose spectral magnitude content is given in Figure 2(b).
In this example the carrier frequency is 80 kHz, thus the transmitted AM signal contains pure-tone carrier spectral energy at ±80 kHz. The purpose of a remote AM receiver, then, is to demodulate that transmitted DSB AM signal and generate the baseband signal given in Figure 2(c). The analog demodulated audio signal could then be amplified and routed to a loudspeaker. We note at this point that the two transmitted sidebands, on either side of ±80 kHz, each contain the same audio information.
In an SSB communication system the baseband audio signal modulates a carrier, in what's called the "upper sideband" (USB) mode of transmission, such that the transmitted analog signal would have the spectrum shown in Figure 3(b). Notice in this scenario, the lower (upper) frequency edge of the baseband signal’s USB (LSB) has been translated in frequency so that it’s located at 80 kHz (-80 kHz). (The phasing method of SSB radio frequency (RF) generation is given in Appendix A.)
The purpose of a remote SSB receiver is to demodulate that transmitted SSB signal, generating the baseband audio signal given in Figure 3(c). The analog demodulated baseband signal can then be amplified and drive a loudspeaker.
In a "lower sideband" (LSB) mode of SSB transmission, the transmitted analog signal would have the spectrum shown in Figure 4(b). In this case, the upper (lower) frequency edge of the baseband signal’s LSB (USB) has been translated in frequency so that it’s located at 80 kHz (-80 kHz). The baseband signal in Figure 4(a) is real-valued, so the positive-frequency portion of its spectrum is the complex conjugate of the negative-frequency portion. Both sidebands contain the same information, and that's why LSB transmission and USB transmission communicate identical information.
And again, in the LSB mode of transmission, the remote receiver must demodulate that transmitted LSB SSB signal and generate the baseband audio signal given in Figure 4(c).

More on Light Beam Telephony


Hi Bill,

Reading about the Photophone and modulating the Sun experiments by G3ZPF reminded me of my own schooldays when as a final year physics project I think in 1970, I and another pupil built a light modulated telephone based on a design published in Practical Wireless of June 1970 by J. Thornton Lawrence. For the optical system it used a pair of spherical mirrors from old projection televisions. The detector was the expensive (for a school kid) OCP71 photo transistor, though we did also try ordinary less expensive OC71 transistors with the black paint scraped off with less success.
As David G3ZPF noted the problem with filament bulbs was the thermal inertia, and as I found it was also possible for the filament to mechanically resonate in the wooden box and start to howl. As we had never heard of, nor could have afforded an LED, we tried a Neon bulb run from an HT battery and modulated with a transformer in series with it. I recall coupling up a broadcast radio as the audio source playing "My Sweet Lord" by George Harrison and receiving it at the other end of the physics corridor very loud and clear on the audio amplifier on our light telephone receiver, much to the consternation and annoyance of the other teachers in the adjacent classrooms.

I found my black and white photo of the light telephone gear, complete with carbon telephone microphone that we used. It did work a fairly good distance in daylight outside across the school playground, not just the couple of feet shown. Also attached are photos of the original magazine cover and index, but regrettably not the article itself.

This was all before I got my ham ticket, but I already was a SWL and had been exposed to a wonderful ham, Tom GM3OWI (Oh Wild Indians) who visited the school and demonstrated all sorts of neat stuff like lighting a bulb from the output of a transmitter, and also voice modulating a klystron 3cm transmitter that the school had for doing electromagnetic radiation experiments, like polarisation, reflection etc.

Come to think of it, we got to play with a lot of stuff at school in those days which would never be allowed now, mercury, radioactive sources, alpha, beta and gamma, X-Ray and UV.  The museum in Edinburgh also had a science area with similar stuff you could play with, and get great shocks from the Van der Graff generator if you put your hand on the glass cabinet and touched the adjacent metal radiator!

Happy days!

73 David Anderson GM4JJJ

Saturday, November 28, 2015

Photophone! Modulating the Sun by G3ZPF (and Alexander Graham Bell, and Mr. A.C. Brown of London)


Yesterday David G3ZPF sent us another very interesting e-mail, this one about some very creative sunlight communication experimenting that he and his brother did many years ago.  It appears to me that David -- on his own -- came up with a version of Alexander Graham Bell's Photophone (pictured above). 

Wikipedia says that Bell's invention was the first ever wireless telephony device.   Bell credited Mr. A.C. Brown of London for the first demonstration of speech transmission by light (in 1878).  

Here is the Wikipedia article: https://en.wikipedia.org/wiki/Photophone 

I think young David's placement of the small mirror on the cone of the AF amplifier's loudspeaker was brilliant! 


Hello again Bill,

Just (literally) finished the book and a couple of surprises awaited me in the final chapters

SSDRA = $200 on Ebay
My flabber has never been so ghasted....and I have a lot of flabber. I will treat my copy with even more reverence now. Srtangely I hadn't heard about EMRFD so I'll need to look into that

Modulating light
Your story about using a laser pen in a receiver reminded me of my method of modulating light which I've never seen anyone else mention.

In the mid 60's my brother had an electronics constructor set for his birthday. After the initial fascination I probably played with it more than him. I remember reading about modulated light transmitters and (because this was before I was anywhere near getting a licence) I decided to build one. My brother was sufficiently curious to help.

We started with the receiver. I purchased an OCP71 and managed to find an old 12" headlight reflector from somewhere. The cork from a wine bottle fitted nicely into the hole at the centre, and the cork was easily drilled out to accommodate the photo-transistor.

My brother constructed the "high gain audio amplifier" project from his constructor kit and we put two legs of the photo transistor across the mic input. We were rewarded by a buzzing sound so loud our parents yelled at us from the other room. It took us a few seconds to realise we were 'receiving' the 50Hz signal off the ceiling light (the house lights were on). Waving the headlight reflector around confirmed this. I still recall the excitement we felt at our 'discovery'.

So far, so ordinary, but the TX side is where I wandered off into the outfield. Normally people modulated an incandescent bulb but this required a many watts of audio power & the 'inertia' of the filament could be a problem.

I cannot remember what prompted me to do this, but next day I pulled the speaker grill off my tiny little medium wave transistor radio and glued a small mirror (from my mothers old 'compact') to the cone of the loudspeaker.

Then we went outside into a field near our house. My brother went to the far end and I set up the lil radio on a camping stool. Moving it around until the sunlight reflected off the mirror hit the headlight reflector about 200 yards away.

Then I turned on the radio. Instantly my brother started jumping up and down excitedly. It worked. My 200mW AF amp was modulating the *SUN* !

All those guys on 160m with their 10w of AM...pah. I had GIGAwatts of power under my control :-)

Looking from the receive end it was possible to see the light from the mirror flickering & I guess the movement of the speaker cone did not move the mirror exactly in the plane of the reflected beam. The 'wobble' fooled the phototransistor into seeing an amplitude modulated beam.

The beauty of this was that only a tiny audio amp was needed. This made me wonder about such a system being used in undeveloped countries (ones with more sunshine) as a comms system, with batteries recharged by the sun.

For the UK I thought about using a slide projector to provide the illumination, instead of the sun. Again a very low power audio amp was all that was needed, and there were no 'inertia' issues to worry about it.

But I was soon to suffer a setback. A few days later the headlamp reflector, sitting on a desk in my bedroom, managed to find itself in a position to focus the suns rays onto the cork holding the photo-transistor. Cooking the transistor & setting fire to the cork. Luckily my mother smelt the burning cork before any collateral damage was caused but I had a face-chewing when I came home from school.

I'd long since forgotten about all this until reading the later chapters of your book.

regards

David G3ZPF










Friday, November 27, 2015

VK3YE's HB Superhet: Simplicity+Serendipity = Elegance



Simplicity + Serendipity = Elegance.  Indeed it does.   I would also point out that Peter's rig contains an admirable dose of ugliness (in the positive sense).  Thanks Peter!

Wednesday, November 25, 2015

Octalmania -- KG7TR's Amazing Thermatron Rigs


Grayson in Turkey alerted us to Mike's homebrew rigs:

Bill, Pete:  

Tuesday, November 24, 2015

M1GWZ's Knack Story: From Crystal Sets to BITXs



M1GWZ writes: "Just to establish my DIY radio credibility, here is a photo of my contest-winning crystal radio. Unpowered, it has logged commercial stations from Ireland to Russia, and from Northern Norway to Algeria. Excuse the mess in the background - the workshop is being re-organized!"


Carissimo Bill (I don't speak Italian. I'm just showing that I have read the book).
One of the benefits of early retirement after ten years in the electronics industry and twenty-five as a University academic is that one gets the chance to research one's interests and also have time to experiment with them. You correctly comment that you doubt you will have trouble occupying yourself in retirement - this is true, but be prepared for the frustration of not making as much progress as you would hope for! Chores still steal your time from you - and you have no excuse for avoiding them when you're retired.
I was recently alerted to the availability of your book via Kindle, but have only just got around to reading it (retirement...). It has been both a joy and a curse. Congratulations! It made fine reading in a couldn't-put-it-down way, but has also added several more items to my already-arm-length retirement project list. This, of course, is the price one pays for education and for evading the curse of boredom. As a radio ham friend of mine says with a sigh, "So many projects, so few lifetimes." As a result of reading your book, I am now pursuing satellite communication with my Yaesu handheld, and will put together a dedicated homebrew Yagi-plus-transceiver system in the New Year. The Baofeng two-bander handheld can now be had for £18 in the UK, so I can afford to dedicate one to the system permanently. Cheap technology to talk via satellites! So far, I have just been listening in - for the last three days.
I have been building radios and short wave listening since I was about nine years old.  If it wasn't for a schoolfriend's father and a crystal set, I might not be e-mailing you now. (They are still talking about killing off MW AM transmissions in the UK. Sad for kids building simple radios, but good news for European DX! Swings and roundabouts.  I'd like to give the Xtal Set Society www.midnightscience.com a mention - virtually all the recent crystal radio technology involved was discussed and developed on their forum. ) Upon graduating in 1980, I found a life without exams strange, so I took and passed my amateur radio licence exams as a way of learning more about electronics. Then life intervened (work, romance, microcomputers, marriage, job changes, son) and it was twenty years before I actually took out the licence. No Morse test so I was initially VHF / UHF only, but later the rules changed and I had a full (phone) licence. However, I only wanted to tinker about with handhelds when visiting friends in the USA (met via crystal radio forums on the internet), so my station consists only of a Yaesu VX-7R and a VX-2R (purchased at Dayton Hamvention) as a backup. I've never wanted to fork out the grand or so for an HF transceiver (although now I'm retired...), but I would like to reach out on 20 metres. Now, curse you, I realize that I have all the electronic parts to build a BITX SSB transceiver - and may have to do so. Another item on the project list...
Apart from amateur radio and DIY discrete-level DIY electronics, it turns out that we might have a couple more things in common. Through visiting the Dayton Hamvention, I now have many friends via the AMRAD club around Washington DC and have met quite a few hams from the Vienna and Loudon groups. I have attended Dayton for about the last fourteen years but circumstances change and we might now decamp to February's Hamcation in Orlando. Meanwhile, I live about four miles away from Kempton Park and have attended most of the rallies there, so there is a good chance that we two may at least have occupied the same room, albeit without actually meeting, on at least one occasion. It's a small, beautiful world.
Anyway, you're a busy man and I'm a verbose retiree, so I just wanted to thank you for the book and the inspiration it has given me to do more in ham radio. I also build DIY audio projects including (music) synthesizers, but at least I can use up a few more junkbox components before they're used to weigh down my coffin.

Regards,

Philip Miller Tate M1GWZ

Monday, November 23, 2015

G3ZPF's Knack Story: Debunking Tech Fairy Tales, Surviving Nixie Tubes and Ferric Oxide



Bill:

I'm finding the book very entertaining, and am currently about halfway
through it. Like you there were a few electronic 'fairy tales' that I
was suckered into and I was pleased to see your debunking of them. My
professional training was structural engineering so anything electronic
I picked up along the road, and was thus an easy mark for misdirection.

I still remember the first time I realized that teachers sometimes don't
understand what they're teaching, but just repeating what they were
told. At age 11 we were using a thin tube with a slug of mercury and was
told that at -273c the air under the mercury would have zero volume. I
knew it was BS, but was too young to know why. A decade later I worked
it out for myself, by accident really, and I still feel slightly
resentful about being misled. Turns out that -273c is a 'convenience'
(aka a fudge factor) which makes the combined gas law work :-p

The first electronic fairy tale I encountered was "the feed impedance of
a half-wave dipole is 72 ohms". Taught to me while studying for the UK
radio exam, and trotted out repeatedly in the RSGB magazine.

This magically mutated into 50 ohms when the Japanese rigs started to appear,
which made me a tad suspicious, and when my very young self finally
scraped enough cash together for the ARRL handbook I spotted the graph
showing variation of feed impedance with height.

I was devastated. I remember wondering why all the old guys at the club
(who I spent most Sunday mornings listening to on 160m AM as an SWL)
didn't know this.

In that instant I saw that all my hours of climbing up & down ladders;
cutting and pruning my very low dipoles to get 50ohms (bear in mind how
changeable and usually awful the UK weather is) had been utterly pointless.

From that point on I used doublets + open wire feeder. Up the ladders
just once and all tuning done in the shack in a comfy chair with a coffee
in one hand using a PROPER balanced ATU, not some shonky single ended
thing with a balun on the back.

Of course I found out about saturating balun cores the painful way (a
T200 core stays very hot for a very long time), and accidentally
discovered the current balun (which I called the idle-mans balun) at a
time when nobody distinguished between a voltage balun and a current one.

I took my inspiration from the 'coax round a ferrite ring' method of
stopping TV coax braid from conducting my RF into the TV. Fast forward
20 years and current baluns are the way to go. Its tough being a visionary.

I remember spending a weeks wages (back in the 70's) on a Fairchild
9H59DO prescaler chip for my TTL freq counter. Like you I hate chassis
bashing and the counter only went in a box after I'd had so many jolts
off the 150v rail to the nixie tubes I figured it was box-it or die :-)





The circuit of the counter was 'designed' by me lifting the simplest
version of each part of the circuit from dozens of peoples designs &
just hoping it worked. By the time I'd finished I had learned enough to
know I was lucky it did work....and what a mess spilled Ferric oxide
makes on a pale grey bedroom carpet.


When GQRP first started up a bunch of us locals used to have a 10m net.
Primarily for ragchews but also to give the newly licensed types at the
club their first ever CW QSO on air. We were all sufficiently enthused
to build a 2w xtal controlled 10m CW TX. Using a 2n3819 in the PA & 2w
meant the matching was easy to 50 ohms.



We were all within a few miles of each other so 599+, so one guy built a
half-watt version. Still 599.

I decided to go for it. Grabbed my sig genny off the shelf. It had a 50
ohm output. Lightbulb moment. Set it to 1microvolt outputans keyed the
aerial with it. 539 all round, albeit with some chirp and drift. Well, it
was a valve sig genny.

1uV across 50ohms is qrpppppp. Thats when I realised the million miles
per watt is no challenge at all when radiating extremely low powers over
short distances.

Might  be harder today though. Back then we could hear the receiver
noise floor on 10m. Not much chance of that now.

But I confess I was always far more interested in operating than
building. Never had the luxury of a workshop. Always tucked into the
corner of a bedroom. If I couldn't hold it in one hand and drill it with
the other it couldn't happen.

I remember hearing that Kennedy had been shot at the instant it
happened. I was on 20m listening to a pair of USA hams rag-chewing and
they both had the TV on. I rushed downstairs to tell my parents who told
me I was talking nonsense "or it would have been on the news". Took a
couple of hours for it to appear on our TV news.

I used to love chatting to the USA novices on 15m CW back in the late
70's. Some of those guys were real pros. You could hear them coming back
to your CQ while screwing the trimmers on their xtals to get co-channel.

I still treasure a letter I have from one youngster. It was his first
QSO outside the USA. He tells how his mom got so excited she ran into
the road telling all the neighbours her lad was talking to England.
.....yes the one in Europe :-)

Life seems a lot more cynical these days.

Even to this day I find the concept of my voice turning into electrons
which throw themselves into space and sometimes hit another piece of wire
in another country and reproduce my voice genuinely 'magical'. Sadly my
grandkids don't 'get it'. They're happy with Skype, facetime, and TXT.

The closest they came to interest was the eldest grandson (at age 10)
saying "grandad, can I have that telegraph key when you're dead?".
Sensing my surprise he added "I'm not interested in morse, but it looks
kinda cool". Now he's 20. Bought his first apartment, and his first BMW.
Making his way in the world and glued to his iPhone.

It would be kinda nice to get back onto 160m AM, but sadly the
electrical 'crud' levels in the UK are S9+ down there :-(

I spent 30 years in front of a TS930, which was able to produce proper
AM because where most rigs had one xtal filter it had pairs of them. You
slide the filters over one another to get narrower passbands for CW and
if you slide them past each other you can gget DSB or AM.

Thanks for taking the time to write your book. You've lived a very
varied and interesting life. I wrote a SciFi novel back in 1980 but at
that time there was only one scifi agent in the UK and she didnt like
it. Maybe I'll get it onto kindle one day.

I was expecting a lot of free time in retirement, but between the 3
grandkids and my 94 yr old mom I have less time than when I was working.
But despite the dodgy knees and eyesight its the best job ever :-)

Regards,

David  G3ZPF
www.g3zpf.raota.org
www.raota.org
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