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

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

SolderSmoke Podcast 182: Bears! MMM Update, On Pete's Bench, 160 AM Dreams, MAILBAG

N6QW Selfie

SolderSmoke Podcast #182 is available

http://soldersmoke.com/soldersmoke182.mp3

Travelogue:  In Shenandoah with BEARS!

Michigan Mighty Mite Update and a Generous Offer (with conditions).

BENCH REPORT:

-- Pete's Ten Tec Conversion using LTSpice

-- Pete's Simple-ceiver

-- My CB to 10 conversion plans

DREAMS OF 160 METER AM:   KB3SII, N2CQR, N6QW Building for Top Band

Raspberry Pi Nightmares

Homebrew to Homebrew (HB2HB) Contacts

Elser Mathes Cup -- We have some competition!

QST, "The Radio Art,"  and The Channelization of HF Bands

WA5BDU Nick Kennedy on QSO Today  Podcast

Ed Walker of "The Big Broadcast" was a ham:  N3HFT

MAILBAG:  A Letter from Turkey: Tubes and R-390s

Si5351:  G4GXO says give it a go!

Listening UP for KIC 846

Update on a story we mentioned a few weeks ago:

Since October 16, the SETI institute has been using its Allen Telescope Array to observe KIC 846 2852 over a wide range of radio frequencies (1 to 10 GHz), looking for any artificial signals. Keep in mind that this star system is relatively far, roughly 1400 light-years away. That's more distant than the Orion Nebula, and getting there (if you feel the need) would require a 23 million year ride in our fastest rocket. But more to the point, any signals detectable here on Earth would have to be exceptionally powerful.

We're continuing to analyze the data. In another week, our SETI team will once again observe KIC 846 2852 using some new receivers being affixed to the Allen Array - known as Antonio feeds - that will increase the sensitivity by a factor of two. Check this space.

Meanwhile, consider KIC 846 2852 as something suggestive of cosmic company, but no more than a suggestion.

http://www.seti.org/seti-institute/news/alien-engineering-around-strange-star

Pete's Suggestion for My Next Rig

 

http://www.classeradio.com/

 

OR THIS:

 

http://www.ebay.com/itm/Harris-MW-1A-AM-Broadcast-Ham-Radio-Transmitter-/191739186033?hash=item2ca48bcb71:g:fx8AAOSwkZhWSR3A 

The Class E rig is very tempting.  But no way on the ebay!  Too much of an appliance -- it even looks like a refrigerator.

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!