Polyvaricon Reduction Drive

Oh man, we need more of these.  Many more.  Unfortunately, this may be the only one.   I pulled this out of an old piece of mystery-gear given to me back in 1994 by my friend Pericles HI8P.   Look at that:  dual turning rates, solid construction, and very small.   This device seems destined to go into my W4OP-built Barebones Superhet (in the background).

Doug DeMaw's Rigs Found, Donated to ARRL for Exhibit

http://www.arrl.org/news/museum-donates-doug-demaw-w1fb-homebrew-equipment

This is really good news (Thanks to Pete Eaton for the alert.)

I wonder if the Barebones "Barbados" Superhet was in this batch.

We KNOW where that Tuna Tin 2 is....  

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Kansas Mighty Mite

Greetings Bill

I have been a bit ill,  but finally found some time to work on my Meara Mighty Mite, which i wish to call it as it was by the grace of Bill Meara that I am able to play a part in the Colorburst Revolution could begin.

I just wanted to share some pictures from the bench of my progress, which is not yet fit for the ether.

I originally wanted to build a really unique design. I have a tendency to complicate things. The more simple it is, the more complicated I tend to make it. After a lot ambitious failed starts, I decided that the best thing to do is to keep it simple. In fact, I would say that I was "over-noodling" this one. So I just started building.

I use copper clad PCB, which I get for very cheap from an ebay seller named abcfab. I use a tool I made to cut islands by hand. Information can be found about this method on my blog.

I am almost embarrassed to share photos of my build, especially after seeing such wonderful designs as you have featured on the webpage. But the excitement is just to great, so here it goes:

I build ugly circuits and I'm proud of it.

I haven't build the LPF yet and wouldn't put it on the air without one. 

Thanks for all the great inspiration and for inspiring a revolution of colorburst liberation!

I want to share something from Solid State Design for the Radio Amateur, W7ZOI & W1FB, page 19

"All of the circuits shown are aimed at reasonable stability, but have relatively low output power. It is possible to bias many of these circuits higher to obtain outputs of up to perhaps 1/4 watt. However, thermal stability is often severely degraded, chirp is introduced if the oscillator is keyed, and the user stands a chance of damaging the crystal from excessive rf current. It is not recommended that a single oscillator stage be used as a simple transmitter. The addition of an amplifier is so straightforward, and the system efficiency is so much better, that the minimal simplicity is not of value."

That may be true, but the Mighty Mite is for learning and getting our feet wet. Still it may be interesting to point the above out or talk about it.

Also, I'm curious to know which schematics everyone is using. The famous Easy QRP transmitter on the QSL page, perhaps DeMaw's from QRP notebook (available on archive.org in pdf form for free).

73, keep your iron hot and stay fluxy,

-KE0BFF, Lawrence KS.

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Broadening the Barebones Barbados Receiver

I've been working on the crystal filter of the Barbados Barebones Superhet receiver.  This was designed by Doug DeMaw in 1982.  This one was built by Dale Parfitt W4OP and then repeatedly modified by me.  It is now on 17 meters with a crystal-switchable VXO.    Earlier I had made a very crude attempt to broaden the filter from its original very narrow CW configuration.    This week I did this again, but this time I actually characterized the crystals and used Wes's LDA and GPLA software (from EMRFD) to design the filter.  

I played with the capacitor values and finally got the 3 kc bandwidth I wanted, but I'm having trouble getting rid of the ripple.   I know this is dependent on the impedances at the two ends.  The programs say I need 2000 ohms.   

I'm kind of puzzled about how Doug DeMaw did this with his original design.  For his crystals and his 250 Hz (!) bandwidth he said he needed 450 ohms.   He used 4.7:1 turns ratio transformers at either end and said that by putting 10k resistors across these transformers he got the needed impedance.  I can see how this would work looking into the gate of the 40673 IF amp, but looking back at the drain of the 40673 mixer, I'm not so sure that that would yield 10k. (See schematic below.)

But who am I to doubt Doug?   So I assumed he was correct about the 10K and I re-wound the transformers with a 2:1 turns ratio, thinking that would get me closer to the needed 2k.   But the ripple is still there.  I guess I could use a return loss bridge at this point... 

I don't know whether this is worth messing with anymore.  The receiver sounds nice.  The 3kHz bandwidth gives it a nice sound, and the ripple doesn't seem to be noticeable  That FAR circuits board is tightly packed and difficult to work with.  So, should I leave good enough alone, or should I proceed with fanatical ripple eradication.  Any advice?

BTW:  Why is it that receivers always seem to sound better when opened up (as above) on the workbench?  

 

 


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Mailbag: Coils Wound Backwards, Last QSO 1981, Visions of Transistors Keeping Him Awake. Paul has THE KNACK

http://www.pan-tex.net/usr/r/receivers/ra01000a.htm

Hi Bill

I'm just getting back into ham radio after 33 years (last QSO: 1981),
want to do it all through homebrew, seem to have the same mindset as
guys like you and Frank K0IYE, bought your book [love it and Frank's],
and just "discovered" the Soldersmoke podcasts.  I've been listening to
them with one ear as I bike to and from work (about 40 minutes each way, so it's almost perfect).  I'm employed as a digital geek, but yearn for the days of DeMaw's prime (worked him once when he was W1CER), when the 40673 ruled.  I'm very glad that, 40 years later, people like Farhan can weave discrete analog wonders, even if they later choose to use digital *control* (NOT DSP! No!).

I had to start somewhere with your podcasts archive, so I started with
2014 and really enjoyed your struggles with the Herring-Aid 5. My 1st
receiver  was the "DC 80-10" by DeMaw from somewhere around 1970 in QST or the Handbook -- used a CA3028 as the product detector -- and I had similar struggles.  While listening to it, I immediately thought "you wound the feedback coil backwards, you idiot!"

I got my license back in March 2014 and want very badly to get back on
the air with a homebrewed, or at least minimally-kitted, station.  I've
built the receiver:  David White's (WN5Y) Beginner's and Experimenters
receiver[1] heavily modified, have a long wire antenna up, a decent RF
ground, and all the parts I need for QRP z-match tuner, swr meter, T/R
switch, sidetone, and IRF510-based transmitter.  Target:  40m CW by the middle of December, 30m in the couple of months after that with a
fully-Manhattan-style Barebones Superhet and another IRF510
transmitter.  Then one of these BitX things.  It's been a couple of
decades since I felt that there weren't enough hours in the day.  Some
nights I can't sleep, what with all these transistors and simple analog
ICs whirling around...

Anyway, keep it up, I'll be listening.

-- Paul Lender, AD0HQ

[1] I built an Arduino/AD9850 DDS -- a la AD7C -- and used it to tune a
4-crystal filter (10-cent crystals from Tayda!) for the receiver with
the same Rigol scope that you use.  I tried, really tried, to do it with
an analog RF signal generator.  Change is good.  Change is good.

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Arduino DDS meets Barebones Superhet (Video)

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Pete's 17 Meter VXO Transceiver (Video)

Pete:  

I like it!  You and I may be the only people in the world with that kind of VXO range control switch on the front panel!

 

I checked my VXO.   I run it at around 23 MHz.  I use two single crystals, also switched by a relay. 

The 23.144 rock tunes from 23.127 to 23.151    24 kHz

The 23.166 rock goes from  23.144 to 23.168    24 kHz

 So I could have had 48 kHz were it not for the overlap.  As it is, I get 41 kHz.  Not bad.

 

The reason I went with this LO freq was that I had these crystals from the Dale Parfitt/Doug DeMaw Barebones Barbados Receiver.  DeMaw had used color burst rocks for a 3.579 MHz IF, but Dale shifted up to 5 MHz. I could occasionally hear WWV!  (But with the 3.579 I heard W1AW in the IF!)

 

73

 

Bill  

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WA7MLH's RD16HHF Amplifier

OK, so now that I have the MOXON in the air, my thoughts are turning to amplifiers and a possible winter project. Hey, even QRP guru Doug DeMaw conceded that every once in a while a fellow needs a few more db. And the sunspot count will be dropping.  

On the BITX group there has been an interesting discussion of using RD16HHF MOSFETs in place of our familiar IRF-510s.  I thought these devices were new, but some Googling this morning led me back to the wonderful website of QRP giant (hey, he is IN SSDRA!) Jeff Damm,  WA7MLH.   Jeff has been using these devices for quite some time.  As with all of Jeff's projects, I find his EXTREME UGLY building methods to be inspirational and reassuring.  Even if you have been there before, you should visit his site:

http://www.neoanderthal.com/wa7mlh1.html

Even his QRZ.com page makes you want to build something:

http://www.qrz.com/db/wa7mlh

Thanks Jeff! 

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FDIM Midnight Mojo Ceremony (Tuna Tin 2)

Tyson Tuna Tin Two

An important message From Rex, 
Transcendental Titan of the Tuna Tin Twos:

 --------------------

Fans of the Ancient Sacred Relic,

If you have a little QRP rebel in you, like me, and are a fan of Ancient Sacred Relic, i.e. The Original Tuna Tin 2 transmitter, and all things housed in round metal containers usually designed for fish products and pineapple, and maybe cats if VERY thoroughly cleaned, then you might want to bring your Tuna Tin 2 rig to FDIM!

Around midnight, after the scrum leaves the FDIM Club night gathering, there will be a Tuna Tin 2 Midnight MOJO ceremony! THE one and only ORIGINAL Tuna Tin 2 transmitter will be on hand for this solemn occasion where major QRP MOJO is transferred from the Ancient Sacred Relic into the tuna can inductees in attendance. Admission is free but you MUST bring a MOJOee tuna can housed rig for entrance to the ritual.

NO rectangular or mint tin equipment will be admitted!! NO unaccompanied minors OR adults OR adults who act like minors will be admitted.

TT2 QRP MOJO will be transferred....FUN will be had.....PRIZES will be raffled off!

If you think you might like to be there for the Tuna Tin 2 Midnight MOJO ceremony remember to pack a tuna can or reasonable facimile (307 (3 + 07/16" diameter) industry standard 2 piece or 3 piece can) housed TT2 style rig in your travel bag!!

REMEMBER: NO rectangular or mint tin equipment will be admitted!! You must have a TT2 inspired rig in you personal possession to gain
admittance! NO exceptions!!

Respectfully submitted,
Rex  W1REX  The TUNA Tinman!
--------------------

 

I will not be at Dayton, but I might be able to lend my TT2 (seen above with Tyson) should some worthy radio amateur wish to participate in the midnight ritual.  Time is short, so if you are interested,  send me an e-mail explaining why you are worthy. 

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"That 70s Show": Steve "Snort Rosin" Smith Restores a 70's era Tuna Tin 2

Hi Bill,

Your recent stories about your TT-2 and original TT-2 "mojo transfer" prompted me to resurrect my TT-2 'resto' project. 

The attached photos show my 70s era TT-2 obtained for $5 from a QRP-L member.  This is how I received it and you can see that it's almost a duplicate copy of the original, complete with 'phenolic' substrate PC board material and hand-scrawled traces. 

I have collected most of the components necessary to convert it to a look-alike of Doug Demaw's 1976 item.  I already have 1 or 2 of the proper Radio Shack RF chokes but lack one more to have the complete set and I'm about to grab some original Radio Shack 276-1617 transistors.  The rest of the missing/incorrect parts I can drag out of the ever expansive Snort Rosin junque box. 

By hand selecting the two transistors for max. power gain I hope to eek 300 mW out of the thing.

Anyway, hope you enjoy the shots and I'll send more when it's finished.

73.......Steve Smith WB6TNL
          "Snort Rosin"

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A Short Video on my Herring Aid 5

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I Too Built a Tuna Tin 2

I didn't plan on doing this.  I didn't even really want to do this.   I've become a phone guy -- I'm not into CW anymore.  I figured I'd just finish the Herring Aid 5 receiver and settle the score from 1976 and that would be it.  But everything I read about the Herring Aid 5 included references to the iconic Tuna Tin 2.  Obviously I was also under the strong influence of my late February encounter with the original TT2 at the Vienna Wireless Winterfest.  That Mojo is powerful stuff!   Then my wife brought home this can of Russian tuna.  The dimensions were perfect.  Then I looked in my junkbox and found 40 meter CW crystals.  That was it. I had to do it. 

I built mine Manhattan style, using several of W1REX's fantastic Me-pads.   I also used as the final a transistor that Rex gave me at Winterfest. Thanks Rex.  Soul in the New Machine. 

I'm getting about 200 mW out.  I;m on 7030 kHz and 7040 kHz and 7110 kHz.   I have the TT2 up with my Drake 2-B (Herring Aid 5 integration will come later).  I can feel the Mojo. 

I just had my first contact with the TT2:  I called CQ on 7110 and AB2RA came back.  Jan was running 20 watts from an old 807 rig, listening with an old Hammarlund.  So it was HB transmitter and vintage receivers on both ends!  FB!





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Some notes on the Herring Aid 5

Sure, this receiver is not "state of the art."  But that's the whole point.  I wanted to finish the receiver project that I couldn't finish back in 1976. 

I tried to stick as close as  possible to the original design and parts.  NORCAL came up with an updated schematic in 1998 with parts that are more readily available.  But Designer Jay Rusgrove was shooting for something that could be built with all the parts coming from Radio Shack.   I think that is probably one of the factors that attracted me to the project way back when.  That's why Jay went with varactor tuning (no hard-to-get variable caps!).  And that's why he used coils that were wound  on Radio Shack 10uH RF chokes (no need for hard-to-find toroidal cores).  In this sense there is some common ground between the BITX rigs and the Herring Aid 5.

I stuck with the RF-choke as a coil idea for the VFO, but went with the NORCAL-prescribed toroids for the front end and mixer coils.  (I may go back and try to use chokes in these circuits, but I'm not sure my junk-box will yield the kind of RF chokes that Jay used).

I wish I had known a few things when I was building this back in 1976: More knowledge about how to wind the coils would have been a big help.  I wish I had realized that I could use a SW receiver to get the oscillator on the right frequency. I guess this was in the days before Ugly and Manhattan building techniques, but it would have been nice to know that there was no need to actually etch a board for this project (I did!).

The coils really are a bit tricky.  Jay didn't use any trimmer caps, so I guess you had to just hope that the front end coil and cap resonated somewhere near 40 meters.   As for tuning the oscillator, Jay recommended scrunching and un-scrunching the turns on the RF choke.  Yikes!  Give me some trimmer caps! 

I also found that you have to watch the level of the RF going from the oscillator to the mixer.   Too much, and the receiver is deaf.  Too little, same result.    You need to experiment a bit with the number of turns on the pick-up coil from the oscillator.   

The warnings about the pitfalls of that single BJT mixer were right on the mark:  Lots of AM SW breakthrough.  But I kind of like the background music.   Strong RFI from local FM broadcast stations was another story (WMZQ is a country music station!).  I reached into my junkbox and found a low-pass filter from a Heathkit DX-60.    I just put that between the antenna and the receiver and the country music was GONE! 

I really love this little receiver.  I have it playing 40 meter CW as I type.  It sounds great.   I feel the urge to built a Tuna Tin 2 and put both of them on 40. 

In the original Tuna Tin 2 article, Doug DeMaw notes that Jay Rusgrove was thinking of doing a companion receiver and says that he was thinking of calling it the "Clam Can 5" !  There were jokes about receivers for hams with "tin ears" and about there being "something fishy" about these rigs.

Thanks to Doug DeMaw and Jay Rusgrove and QST for bringing us these little circuits. 


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Tuna Tin Mojo Transferred to BITX17!!!!!!

It happened at the Vienna Wireless Society's Winterfest Hamfest today in Northern Virginia.
That is Doug DeMaw's original Tuna Tin. 
This may be the first time TT Mojo has been given to a phone rig. 
Doug DeMaw would, I'm sure, approve.

Thanks Rex!


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The QRP Mojo Ceremony

More from Lobstercon (from N2HTT): 
 http://n2htt.net/2013/11/24/there-are-lobsters-in-the-woods/
And thanks to Pete, VE2XPL, for alerting me to all this. 

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W4OP -- Earth-Moon-Earth and Another Barebones Superhet

Years ago I bought a Barebones Superhet from Dale Parfitt on E-bay.  Several years after that, having forgotten who I bought it from, I was asking questions about how to get it working on 17 meters.  Dale jumped in with some very helpful e-mails.  It took us both a while to realize that I was working on the receiver that he had built.  Dale is active in a really wide range of ham radio activities, everything from QRP to EME.  Check out his homebrew projects here (I really like his Solid State Drake 2-B!) http://www.parelectronics.com/par-homebrew-projects.php 
And his vintage projects here: http://www.parelectronics.com/vintage-radio-restoration.php
And here's what Dale has been doing with the Moon (that's his 15 foot dish in the picture): 

 

Hi Bill,

 

I thought of you today when I won a Bare Bones Barbados RX on eBay for $5. I am going to team it with a DDS VFO and a matching TX.Some parts are apparently missing, but i have a huge junk box and also know how to order from Mouser should the junk box fail me.

 

 

Right now I am putting my solid state 650W 1296MHz EME amp , Power Supply, meters etc. in its waterproof cabinet so I can mount it right at the dish and not incur any feedline losses.

 

1296 is probably the best EME band. Power is getting easier and easier to acquire (although solid state is around $5/watt), dishes are fairly easy to acquire or build and  perhaps most importantly, we all use circular polarity feeds with no relays/hybrids. Activity weekend can sound like 20M, with a number of stations just ragchewing on CW and SSB.

 

73,

Dale W4OP
for PAR Electronics, Inc.
http://www.parelectronics.com

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Standard Computer Crystals for 17 Meter SSB VXO and IF Filter

Pete Juliano, N6QW, is an electronic  genius.  The ideas in his SPRAT article will be of great use to all those who share in Doug DeMaw's devotion to VXOs and reluctance to spend money.  I'm really tempted to go back and re-do my BITX using Pete's 11.52 MHz computer crystal super-VXO and 4.9152 IF (I could then take my expensive 23.1 MHz crystals and put them back in my Doug DeMaw Barebones Superhet).  I also like Pete's DPDT reed relay crystal switcher too.  Three cheers for Pete Juliano, Doug DeMaw, and SPRAT!  And thanks to WB9FLW for reminding us of Pete's articles.

Hi Bill,

 

Your BITX17 really has me fired up! I came across an interested Super VXO by Pete N6QW for use on 17 Meters.

He uses standard computer xtals (4.9152 MHz for the IF) and (3 - 11.520 MHz freq doubled in the VXO)

This gets you on 18.120 to 18.150 using these two standard xtals.

See Link Below:

 

http://www.jessystems.com/SPRAT%20Article.pdf

http://www.jessystems.com/Images/23%20MHz%20VXO.jpg

http://www.jessystems.com/vxo2.html

http://www.jessystems.com/switchedxtalvxo.html

Thanks for all your efforts they are much appreciated!!

Best Wishes,

Pete WB9FLW
 

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Knack-to-the-Max! Early Moonbounce

The link below will take you to an amazing collection of QST articles describing the early days of EME or "moonbounce."  Very interesting.   I was really blown away when I found out that Ross Bateman, W4AO, (pictured above, on the left) did the very first amateur moonbounce work from the small suburban Washington town that I live in now -- Falls Church, Virginia!

I am trying to find OM Ross's old address or more info about him.  If anyone has an old callbook, could you please look up Ross Bateman, W4AO, aka W4XNB?   He worked at the National Bureau of Standards. 

The moonbounce story is filled with interesting technology and characters and clubs.  Sam Harris and his Rhododendron Swamp VHF Society sounds like our kind of group!  Scroll through the OK2KKW web site and you will come across our esteemed Doug DeMaw and Bill Orr. 

http://www.ok2kkw.com/eme1960/eme1960eng.htm

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Yikes! Screeching Transistors Throwing off Blue Light!

I found a quote from Doug DeMaw that I wanted to share.  This one seems appropriate as I struggle with unwanted oscillation (and as Halloween approaches). From the January 1986 QST:

"Self -oscillation occurs not only in the low-frequency and high-frequency spectrum, but it often takes place at audio frequencies!  I have actually heard the transistors "screeching" when strong audio oscillations were taking place in a homebrew transistor power amplifier. On one occasion I could see a bluish glow coming from within the transistors (visible through the ceramic heads of the devices) during a period of instability.  Needless to say, the transistors self-destructed."

I've been having some instability problems with my BITX 17 IRF510 final.  But I think I have the problem identified.  I was getting low frequency oscillations (around 100 KHz).  Tonight  tried putting the IRF510 on a separate power supply.  The oscillations ceased and I am getting a nice clean 3 watts out.   So I'll go back and beef up the decoupling on the power supply lines.


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BITX Build UPDATE # 5: ADRIFT!

Sometimes it is better to have LESS test gear.  Watching my 5 MHz VFO on the frequency counter was driving me nuts.  If I hadn't had the counter, I might have been satisfied with the VFO.  Ignorance is bliss!   It did settle down a bit.  But then it would wander off.  I hated watching it drift around.  I have been spoiled by Doug DeMaw's VXOs.   So, I went for the VXO.   It will run around 23 MHz.  I'll build the filter at 5 MHz.  That's definitely the plan.  For now. 

I intend to go back and build a real VFO someday.    There seems to be a lot of magic and lore involved.  Bees Wax!  Hot Glue!  Nail Polish!  Q-Dope!  Air-wound coils!   

TEK 465 is still broke.   I think it is the high voltage supply or (less likely) the CRT. 

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