Author: Peter Marks

AM Madness: Just When You Thought It Couldn’t Get any Cooler…

I pulled an old Eico 435 ‘scope out of retirement. I hope to use it as a modulation monitor (any suggestions on easy ways to hook it up for this purpose?). I really like the grey and aluminum look of this station. I tried putting a DX-60 on the same bench, but the green of the “modern” Heathkit clashed with the serious-radio look of the DX-100 and HQ-100. Thanks again to Tim Sutton for the aluminum boxes — I am temporarily using them as supports for the D-104 and the ‘scope. You see, I’m standing up when I modulate this gear. Somehow it seems right. Also, the transmissions on AM are so long that you can go back to your chair and rest (a lot!) between your transmissions. When your turn comes, the few seconds it takes you to get to the rig provide the customary (and polite) “dragging of the feet” that allows others on the frequency to announce their presence. Then comes what is perhaps the most fun part of this setup: the AWESOME KERCHUNK sound of the DX-100 going from receive to transmit. As you can see, we pay a lot of attention to aesthetics and radio ergonomics here at SolderSmoke HQ. That little blue recipe box holds my AM contact card file from the 1996-2000 period of operations from Northern Virginia.
I’m planning on doing a little work on the DX-100. There is a standard set of mods to the audio amplifiers, mostly just changing some caps. And I need to find out why some of the crystals are not working — I suspect dirty contacts. I might also change the mic connector. Looking ahead, Steve Silverman KB3SII (SolderSmoke Lex-pert), Pete Juliano N6QW and I have vague plans for an assault on 160 meter AM.
Over the weekend this rig yielded a number of really FB contacts. Brett N2DTS in South Jersey was running an amazing homebrew station:

And Now for Something Completely Different: Boatanchors! AM! Top Band!

Lately I found myself looking for something different to get involved in. Pete’s conversion of his Ten-Tec commercial rig got me thinking about converting an old CB rig to 10 meter AM. I’m still planning on doing this, but noodling on this project got me thinking about AM in general. I had the DX-100 that John Zaruba K2ZA had given me (it was his dad’s). I had it paired up with an old HQ-100 that I’d picked up in the Dominican Republic 20 years ago. (Looking at the old manual for this receiver, I realized that there is another reason why I feel so connected to it: it was built on West 34th St. in New York City, not far from where I was born.) On Veterans Day (November 11) I connected these two old Boatanchor veterans to my 40 meter dipole, rigged up a connector for my Astatic D-104, and fired up on 40 meter AM.
I had a blast! I found myself in contact with hams who are interested in the inner workings of their gear, guys who know which end of the soldering iron to grab. The DX-100 got great reports — people said it sounded nice.
Sam K4NDY told me that his DX-100 had started out at 100 pounds, but that as time passed (and as he has gotten older) he noticed that it has somehow increased in weight!
Bill K8DBN was running a DX-60 and (like me) an HQ-100 (you see, we’re no longer in Yaesu-Icom-Kenwood land!)
Mike KC2KJ was running a DX-100 and a Drake 2B. FB!
Steve W3DEF was on with his B&W 5100B.
Dave W3CRA was on from the Collins Radio Association. He restores Collins gear. When he told me the DX-100 sounded great, I knew that it really did.
Today I talked to Ed KA3PTX who has this really cool Boatanchor station:
And also today I had a great contact with Howard Mills W3HM, one of the greats in the world of radio restoration. Another fellow on frequency asked me to makes some critical comments on Howard’s signal quality (“Does he have too much low frequency?”) — I refused, saying I was unworthy. (I did say that he sounded great — he did.)
Anyway, I’m out of the rut. An added benefit is that this new (old) interest moves me even further away from microscopic SDR rigs, and closer than ever to the Hardware Defined, analog, discrete component, menu-free radio that I prefer. Check out the full schematic of a DX-100 — simplicity, clarity, beauty:

I had been thinking vaguely about someday getting on 160 meters — I’ve never used those frequencies. Yesterday I noticed that both the HQ-100 and the DX-100 cover this band. THE RADIO GODS HAVE SPOKEN!

W2DLH’s 20 meter Mighty Mite

N2CQR & N6QW,

I ran across a reference to the SolderSmoke book and read through it very quickly. Through the book, I discovered the SolderSmoke podcast and have been enjoying every minute!
I just want to thank the two of you for the inspiration and new motivation I’ve found in a hobby I’ve loved for 25 years! I’ve never tried homebrewing anything but that’s about to change.
It took me a while but we have oscillations on or about 14.060 MHz!
I adjusted the circuit to use resistor divider biasing of the 2N2219 and changes to the biasing and coil to accommodate the 20m crystal. Also the only cap I had that worked was a 10-50pF trimmer. Aside from my placing the crystal in the wrong point in the circuit because I wasn’t paying attention, this Michigan Mighty Mite needed minimal tweeting. The antenna is a 50 ohm resistor which the KX3 heard very well with its attenuator in line.
Now my problem is that I listen to SolderSmoke in the car and it’s bad form to take notes and drive at the same time. Also, I find myself wanting to experiment with all of the ideas from the podcast at once… If I build your LBS in modules, Pete, then I can experiment later and swap circuits to my hearts content.
One question for now…where is a good source of plentiful, inexpensive crystals?
Thanks again, guys!

Darryl Hambly, W2DLH
– – – – – – – –
Grid DM78pu
G-QRP 15014
QRP ARCI 15138
SKCC 10990
– – – – – – – –http://www.qrz.com/db/W2DLH

Waco Mighty Mite Mojo!

Eric: Wow, great news from Waco. JOO indeed! And I really liked the WAY you did it, liberating crystals and wire from old TVs. That definitely adds mojo to the Waco M^3. Bill

Hello Bill,

My name is Eric Melling KD0OXY. I have, as of tonight, officially passed selection for the CLA. My Michigan Mighty Mite began oscillating tonight between 1830 and 1900 CST and I am ecstatic about it! My foray into home brewing began mid-2011 when I obtained my general class ham license (I took Technician and General at the same time taking advice from my late grandfather). The first radio I ever purchased was the Pixie II kit and boy was that frustrating. I meticulously assembled the kit and worked very hard to stuff the transceiver, volume control, options to use the on-board key or a straight key, and maybe an on-board speaker or phones. But, to my chagrin, I was treated to the sweet wafting smell of the magic smoke long before ever getting on the air. I eventually did get on the air with my aforementioned grandfather’s VHF/UHF HT and until recently, this has been the extent of my Ham career.
But on the advent of my starting an MA in applied linguistics at a school in Dallas (hour and a half from home in Waco) and the rekindling of my electronics knack occurring near- simultaneously with my discovery of the SolderSmoke Podcast, I decided to give it another go. First, I got the old pixie kit to oscillate and then ripped it apart for parts to another project (non-radio). Then I procured a second Pixie kit from ebay and built that. It oscillated right away! Still no contacts; my CW is… improving.
All this to say that I still had an itch that wanted scratching Enter: The Color Burst Liberation Army! Not only could I truly build something from scratch, I could follow my true calling and de oppresso liber some crystal. So I pulled some 30 (or so) gauge magnet wire from an old CRT. I had wound and rewound my coil three times (and unfortunately, the third one looks the worst) for 80m then 20m (far fewer turns) and back to 80m with N’JOO (No Joy of Oscillation) in any configuration. I am using a polyvaricon pulled form an old AM/FM transistor radio, the Mitsumi PVC-2FX which has 82 pF, 140 pF, 20 and 40 pF sections which I have wired in parallel giving me ~0-282 pF of range? And finally, I was using a MPS A42 NPN transistor. I had to run some resistors in parallel and some caps in series to get the right values, but I eventually got it all together and looking pretty smart on a 1″ x 1.5″ piece of perf board. Alas! Nothing!
I was poking around at the circuit and realized that when I keyed the transmitter, the coil would get really hot right at the tap. I still don’t know why that was, but I figured it was a good sign as it meant something was happening. I also was getting plenty of pops and clicks on the receiver. Anyway, to make a short story long, I decided that the dark mark under the transistor was a bad sign, found an NTE 123 and plugged it in instead. And oh what a wonderful day to hear the first warblings of my very first all scratch built transmitter hitting the airwaves! And here is the video: https://youtu.be/yq2M1ryMkII
Probably more than you wanted to hear, but there it is. I do plan to build an SSB transceiver someday (hoping sooner than later). I feel you and Pete and your podcast have really set me out on the right foot! I hope to HB2HB with you soon!

Sincerely,
Eric KD0OXY

Psst… I know a guy with some caps…. Variable caps… Real beauties…. But only for Mighty Mites.

Feast your eyes my friends. That is 400 micro-microfarads of variable capacitance. (400 picofarads for you sophisticated young folks.) A benefactor interested in expanding the ranks of the Color-Burst Liberation Army has stepped forward to make us an offer that is hard to resist: He will send ELIGIBLE recipients one each of these fine electronic components for the cost of postage (approximately 6 bucks in the USA).

He has specified that ELIGIBILITY is limited to those who need this part to build or complete a Michigan Mighty Mite. And I have been appointed “Grand Poobah and Chief Arbiter of Capacitor Eligibility.”

So here is the deal: Send me an e-mail telling me about your planned or stalled Michigan Mighty Mite project. Include some information about your personal “Knack Story” — tell us why you share in this strange compulsion to build a largely useless 250 mW 3.579 MHz oscillator. If I find your plans believable and your Knack Story compelling, I will recommend you for a capacitor. Purely aspirational MMM projects and obviously fabricated Knack Stories will not make the cut.

Supplies are limited, so act now!

Words of Wisdom for Homebrewers — From Dave Metz, WA0AUQ

When you are done, be proud of what you have accomplished! Use it on the air and show it off to your friends an amaze them. Then clean the bench and start dreaming about your next project.


Summary:

  • Decide if its important to do
  • Study the prior work of others
  • Make a preliminary simple design, document everything you do!
  • Round up your parts
  • Build in modules! Make one module at a time work.
  • Don’t get discourage, ask questions, finish what you start

http://www.fpqrp.org/homebrew.html

There is a lot of tribal knowledge and homebrew wisdom in this link. I tried to find a picture of OM Dave, but he has kept a low profile on the www. The best I could come up with is a symbol of the club that he has been associated with. Thanks Dave!

Here is the full document:
http://www.fpqrp.org/homebrew.html

Brazilian Minimalism: The Curruira Transmitter

Miguel PY2OHH is the Wizard of Sao Paulo. This morning I was looking at his wonderful web site and came across this little rig. It seems a bit simpler than our beloved Michigan Mighty Mite. And the folks down in Brazil had several of these on the air and made contacts with them. FB. Miguel hints they may turn this rig into a transceiver.
Here is the Curruira:

The rig is named for this little bird: 

Gregory Charvat HAS THE KNACK

Gregory Charvat N8ZRY

Yesterday I was talking to Allen W5SQK on 17. He mentioned that he been working in his shop. You don’t hear that too often these days, so naturally I asked what he was working on. Turns out that OM Allen is building a coffee can radar! He is enrolled in the MIT Lincoln Lab’s Open Courseware Project (which looks very cool). We had a great QSO, sharing tales of woe about the release of magic smoke from (dis)integrated circuits. These are the things that pull us together my friends!
On the MIT page the name of a faculty member caught my eye: Dr. Gregory Charvat N8ZRY. Greg’s rigs have been discussed on this blog at least twice, but it wasn’t until today that I became aware of his many other interesting technical activities.
Videos:
Greg’s KNACK STORY:

Nightmare Turns Real: “Rig Here is a Raspberry Pi OM, and I’m listening to you with my Dongle…”

As with many other nightmarish things, this one was launched at the world on Halloween. It all seems a bit flaky, but we knew this was coming. Don’t complain to me about the lack of low-pass filters, SSB testing on 7.000 MHz, or the rather nebulous identity of the creator…. I’m just the messenger here. And remember that I am a HARDWARE Defined Radio, Discrete Component, “Menus are for Restaurants” and (now) “Pi’s are for eating” kind of ham.
Here it is:
http://www.rtl-sdr.com/transmitting-fm-am-ssb-sstv-and-fsq-with-just-a-raspberry-pi/


CB to 10 Conversion? The Radio Gods Seem Ambivilent

A lot of trouble can begin with a 5 dollar purchase, as I found out after I bought a nickel bag of CB at a hamfest.

The embarrassing little Good Buddy appliance has been hidden away in my junkbox for a while. I pulled it out after watching Pete’s videos about the conversion of his Ten-Tec Model 150A commercial rig. I thought perhaps I could use a little DDS or PLL board to bring that CB rig onto 10 or maybe even 12 meters.

The first thing I noticed when I opened it up was the smell — there was a very strong chemical electronic smell. It was as if components and wires and adhesives and PC boards had been venting inside that case for several decades. This wasn’t that pleasant electronics smell that you get from a Drake 2B or a DX-100. No, this was different. It gave me a bit of headache. That’s a bad sign. I began to wonder if the Radio Gods might be sending me a message.

But then I found this very cool conversion site:
http://www.jcoffman.net/WB5RUA/10_meter_AM_conversion_w_Photos.html

Wow, a few snips, a few jumper wires on the PLL board, and a few coil tweaks and that thing would be on 10 meter AM. I also learned that the “Cybernet” board that was stinking up my shack was VERY common in CB rigs, so there is a lot of info about it on the internet. This thing seemed to be crying out for a quick and easy conversion to ham-dom.

So I don’t know which way to go with this one. I’m getting contradictory signals from the Radio Gods. What do you guys think? Garbage can or workbench?


Rocket Knack in the Congo

Ground control for Mr. Keka’s space program is a shed with a tin roof. Inside are old computers and televisions.

This guy clearly has a rocketry version of The Knack. Busted by the police for a match-stick rocket at age 17, Jean Patrice stuck with his dreams of a Congolese space program. Years later, when the rat flying in one of his rockets crashed and burned, he declared that the varmint had “died for science.” Indeed he did. That is what I said about the lizards and mice killed in the payload chamber of my Astron X-Ray Estes rocket during the late 1960’s. A moment of silence please…

Imagine how difficult it would be to make any progress on something like this in the Democratic Republic of the Congo. Godspeed Jean-Patrice!

http://www.wsj.com/articles/one-africans-personal-space-race-turns-vermin-into-astronauts-1446239060

Rocket Knack in the Congo

Ground control for Mr. Keka’s space program is a shed with a tin roof. Inside are old computers and televisions.

This guy clearly has a rocketry version of The Knack. Busted by the police for a match-stick rocket at age 17, Jean Patrice stuck with his dreams of a Congolese space program. Years later, when the rat flying in one of his rockets crashed and burned, he declared that the varmint had “died for science.” Indeed he did. That is what I said about the lizards and mice killed in the payload chamber of my Astron X-Ray Estes rocket during the late 1960’s. A moment of silence please…

Imagine how difficult it would be to make any progress on something like this in the Democratic Republic of the Congo. Godspeed Jean-Patrice!

http://www.wsj.com/articles/one-africans-personal-space-race-turns-vermin-into-astronauts-1446239060

De-mystifying a chip — Looking inside the 741 Op-Amp

Inside a 741 op amp, showing the die. This is a TO-99 metal can package, with the top sawed off
Inside a 741 op amp, showing the die. This is a TO-99 metal can package, with the top sawed off


This is really cool and potentially life-changing for radical fundamentalist ludite homebrewers. As our readers will know, my big objection to the use of integrated circuit chips is the fact that these little black boxes are in fact often, well, little black boxes. We don’t know what is going on in there. It seems to me pointless to shy away from the use of large black boxes (the extremely complex “radios” that dominate the amateur airwaves today) only to fill our homebrew rigs with smaller black boxes.

But when we crack one of these boxes open and take a look at the transistors, resistors, and capacitors formed on the substrate, then diagram it all out, I think the fog of mystery is blown away by a refreshing wind of insight and understanding. We saw this happen on a much smaller scale when someone cut open an SBL1 mixer, but that wasn’t an IC. Ken Shirriff has now done this with the venerable 741 Op Amp. And he did it with a hack saw. Bravo Ken. I can now in good conscience uses 741 op amps in my rigs.

http://www.righto.com/2015/10/inside-ubiquitous-741-op-amp-circuits.html

Listen to my BITX17 Signal as Heard in France

I was talking to Alan F5LIW on 17 meters yesterday and he was kind enough to record a bit of my transmission and then e-mail it to me. So here is what my BITX 17 sounded like in Dijon, France. I had the BITX17 going into the CCI EB63A amplifier running at about 100 watts into my Moxon antenna. Thanks Alan! 


http://soldersmoke.com/N2CQRF5LIW.mp3

Real DX: The Mysterious Flicker of KIC 846

Artist's conception of a Dyson Sphere. Image Credit: Kevin Gill via Flickr CC By SA 2.0
Artist conception of a Dyson Sphere Alien Mega-structure

This story somehow seemed appropriate for Halloween. But it is for real (this is Halloween, not April 1!). The role of amateur scientists in this matter is especially interesting, as is the radio-astronomy follow-up. Stay tuned!

Si5351 — G4GXO says “Give it a go!”

Hi All,
Many of you will know of the low cost Si5351A programmable clock generator which can serve as a VFO with a remarkable range of 2.5kHz to 200MHz. This device is available from the larger industrial component suppliers such as RS for as little as £0.68 +VAT and is offered as a small PCB module with regulator and level converters from many amateur component suppliers for around £7.00. I bought a couple of the Adafruit modules to evaluate as the second conversion oscillator in a DSP IF system I’m developing and once I’d overcome the hurdle of writing the dsPIC33 software to drive the device I decided to test the unit as an HF VFO. My reason for doing this was to assess the phase noise of the si5351A; a quick Google will turn up many blogs and forum listings on this subject with mixed opinions of the suitability of this device for VFO service. With no direct method of measuring phase noise I decided to examine instead the impact of phase noise on receiver performance, after all it is this effect that will determine the suitability of the Si5351A as a VFO. My strategy was simple, I used the receiver section of my 60m SSB transceiver which is based upon the Eden IF (SPRAT 144) and uses one of the club 9MHz SSB filters. The front end mixer is a discrete diode ring made from two trifilar wound FT37-43 toroids and four 1N4148 silicon diodes. Unlike a schottky diode mixer this silicon switching diode version requires more drive to keep conversion loss down. The VFO is a low phase noise 7ppm Si570 running on the high side of the IF at 14MHz, a MMIC output stage delivers +10dBm of drive to the mixer. The Si5351A was compared directly to the Si570 – which is a known “very good” performer.
The test strategy was to measure the receiver Minimum Discernable Signal (MDS) at 5MHz with the Si570 and the Si5351A as the VFO. With no buffer stage to raise the 5dBm output of the Si5351A to match the +10dBm output of the Si570 VFO module, I accepted that this compromise would have some bearing on the results through increased mixer loss.
Results (14MHz oscillator drive, 2.2kHz IF bandwidth)
Si570 +10dBm output, MDS –122dBm (Well below noise from the antenna, perfectly acceptable for 60m!)
Si5351A +5dBm output, MDS –118dBm (Note, mixer drive 5dBm down!)
Some if not most of the 4dB difference in MDS is without doubt attributable to the lower drive power of the Si5351A in my test configuration, this is borne out by the AGC threshold which moved up by 4dB suggesting increased mixer loss. I’m confident that had I been able to match the +10dBm output of the Si570 then it would have been a close match. My conclusion is that for HF at least the Si5351A is a very useful oscillator which is easily applied and can deliver good performance. If you had doubts about using this device at HF I hope that these results encourage you to give it a go!
73 Ron G4GXO