Showing posts with label Hallicrafters. Show all posts

Kiwi Lunchbox Sideband: The Tucker Tin Two

Pete Eaton sent us links to an old article from the New Zealand magazine "Break-In."   So many good, simple rigs come to us from New Zealand!  Who can forget ZL2BMI's DSB rig?  This one is the work of Fred Johnson ZL2AMJ.  It is especially interesting and is in some ways similar to Peter Parker's "Knobless Wonder."

It uses the phasing method of sideband generation.  No crystal filters in this one.  You need TWO balanced modulators.  You have a 90 degree phase shift network for the RF (from the carrier oscillator) and a second 90 degree phase shift network for the AF from the mic amplifier.  When you combine the signals from the two balanced modulators -- viola! -- one of the sidebands disappears.  The balanced modulators take care of the carrier, and an SSB signal is launched.  That is how my old HT-37 works, and similar ideas seem to be at work in modern SDR rigs.  

G3TXQ has the complete set of Break-In articles (it includes a VFO): 
http://www.karinya.net/g3txq/temp/tucker_tin/   

Here is a Canadian article on the rig.   A "Tucker Tin" is apparently what the Kiwis call a lunch boxes (shades of Benton Harbor...).  


Thanks Pete!

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Harv's DDS Function Generator


Nice looking DDS function generator Harv!  Glad to see the HT-37 in the background. (And it appears well protected -- is that some sort of digital shielding to protect it from the bits and bytes?) The eraser buttons are a nice touch. Good luck with the Minima!

Hi Bill,
 
Well I have nearly completed my DDS Function Generator as I prepare to construct the Minima.
 
The Function Generator was a necessity for the bench so I can tackle Tweaking and Troubleshooting my work.
It is housed an aluminum box and completely self-contained.
My objective was to have the choice, to either lay the unit flat on the work surface or stand it on a shelf for easy reading while seated.
The Generator has both a  DDS and HF-ECG output.
The buttons are fashioned from White Pencil Erasers since finding proper buttons for the membrane keypad beneath was difficult.
 
I have obtained a set of Farhan’s Boards for the Minima but will begin my effort with a Manhattan Style Construction so I can perfect my choice of parts.
The soldering iron is heating and I’m ready for a new and exciting challenge.
 
Happy Solder Melting Everyone!
 
Harv -=WA3EIB=-
Albq., NM.


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38 Year HB Mystery Solved? Was it the phasing dots?



 During the summer of 1976, at the age of 18, I made an audacious attempt to join the ranks of the true homebrewers.  I tried to build a receiver.  It was the Herring Aid 5 from the July 1976 issue of QST, a 40 meter Direct Conversion receiver intended for use with the famed Tuna Tin 2. As I have recounted (perhaps ad nauseum), I never got it to work.   My recent encounter with the ORIGINAL Tuna Tin 2 (Mojo was transferred to my BITX17, and it definitely works better now) got me thinking about this painful experience.   I decided to try again.

There is an updated NORCAL schematic for this rig.  I found it (and some good articles) on the NJQRP club page.   In the original, designer Jay Rusgrove, WA1LNQ, used only parts that could be found at Radio Shack stores.  In the days before the internet and Mouser, this was a good idea.  Instead of toroidal ferrite and iron powder coils,  Jay built his coils around Radio Shack solonoidal 10 uH chokes. 

The NORCAL version dispensed with the Radio Shack chokes, and used toroids.  But I wanted to try to find out what went wrong 38 years ago.  So I dug up some 10uH chokes. 

I know that my problem was that I never got the oscillator working.  I remember being able to hear signals with my "almost" receiver when I put my HT-37 in "CAL" mode and tuned through 40.  I was so close!  The Herring Aid was picking up RF from the HT-37 and using that in lieu of the LO energy that obviously wasn't coming from my Herring Aid VFO.  But WHY didn't that oscillator work?

Today I started with the VFO.   Again, it didn't work!   But now I have decades of troubleshooting experience under my belt.  So I poked around a bit.  Then I decided to look closely at the phasing.

Take a look at the schematic(above) and the picture (below).  L7 is the 10uH choke.  L6 is 4 turns wound over it (or adjacent to it).  Now, here is the key question:  Look at the phasing dots.  How would you guys connect those coils?   For me, the schematic indicates that the TOP of L6 should go to the Zener and the BOTTOM of L6 should go to the drain of the JFET.   The TOP of the choke should go over to C5, and BOTTOM of L6 should go to ground.  Right?  Or am I reading the phasing dots wrong?

Well, the oscillator was not oscillating in this configuration.  Then I did something that I might not have known to try back in 1976:  I reversed the phase of L6:  I put the top of the coil to the Drain of the JFET and the bottom of the coil to the Zener.  Bingo.  The joy of oscillation.  Now it works.  (The picture below shows it as it is when the oscillator is working well.)

So,  is there an error in that diagram?  Was this not all my fault?   


Aha! I just looked at the schematic of the NORCAL version.  Check out the dots!   I think that was the problem!


 


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First Light


Preston:  Your use of the term "First Light" is especially appropriate.  I got the concept from a wonderful book of that title by the author Richard PRESTON.  I pulled it off the shelf this morning, and, as my coffee was brewing, read this on the dust cover:

"First Light won the American Institute of Physics award in science writing. An asteroid has been named "Preston" in honor of First Light. It is likely someday to collide with Mars or the earth."

The book's glossary defines first light as: "A technical term from astronomy signifying the moment when starlight is allowed to fall on a new mirror for the first time."  The first light experience must, I think, be similar to the feelings we get when we first allow RF to fall on the front end of a new homebrew receiver.

Congrats on the S-107 OM.

73  Bill N2CQR
------------------------------------------

From Preston Douglas WJ2V:

I am happy to report that my little novice rig (well it's not so little if you weigh it) consisting of my restored circa 1960 Hallicrafters S-107 and circa 1959 KnightKit T-50 (with V-44) made our first QSO with a guy 20 miles away on Staten Island.  This was Saturday afternoon, in full daylight, on 40 meters.  He was also running vintage equipment (Heath) but running an SB-200 Heath linear.  I have no idea why he needed a linear on 40 meter CW, but he seemed happy with it.  I could easily hear his signal via leakage through my Daiwa cavity switch, so it was a pretty powerful signal.  The T-50 puts out maybe 20-25 watts full bore, but it certainly works fine, and got a 569 signal report.  The 9 part was obviously the important one.
 
I had just turned on the equipment, so the S-107 needed to be adjusted a bit during the QSO to allow for a bit of warm up drift.  It stabilizes ten or fifteen minutes after warmup.  I had to use a straight key as I have not yet built the little kit that interfaces solid state keyers with old rigs.  I'll get to it on a slow afternoon this winter perhaps.  But for now, a straight key is about the right speed for this setup.  T/R requires switching the antenna, the VFO to transmit, and the receiver to standby for transmitting.  Not exactly QSK. Since there are so many switches, it may not pay to add an antenna relay switch to this setup.  Besides, switching is part of the fun.  

I did not get set up in time for New Years, so missed the chance to operate SKN.

I learned about first light from Bill Meara's podcasts.  It refers to the first time a telescope is used, but, as he says, it applies just as well to a new (old) rig.

All of this was caused by a local ham offering a Hallicrafters S-107 for ten bucks. Even with the few bucks needed to put it right, I sure got my money's worth.  

Regards guys and Happy New Year,

Preston WJ2V
----------------------------------------
 
Earlier from Preston:
 
I am pleased to report my S-107 is restored to full function.  Based on the build up of filth on it before cleaning, it is also cleaner than it has been for many years.  The greasy dirt (I shudder to think what it was made of) in between the flutes of the control knobs has succumbed to a toothbrush and detergent.  Who'd have thought what a difference clean controls would make in the overall appeal of a radio?

The S-107 was purchased without negotiation from a local and fellow member of the Long Island Mobile Radio Club for ten bucks.  I cheerfully handed over a ten spot and drove home with this rig.  

On the bench, the tubes lit, and I could hear a couple of AM stations, but it made an awful racket with 60/120 cycle hum.  New electrolytic caps cured that.  The chassis felt "hot" to the touch.  Resistance checks on the HV-to-AC sides of the transformer confirmed that, thankfully, there were no shorts.  On advice of some pros on this list and elsewhere, I removed a cap and resistor from the AC line to the chassis that Hallicrafters thought was a good idea.  With a new three wire grounded plug, the chassis was now cold.  

Alignment was done with an old Conar signal generator (my $1 victory from an old hamfest) and trusty Tek 465 with frequency counter connected to its rear connector.  The double IF transformers peaked up, and so did the front end compression caps on all bands.  And now, the radio really receives CW and SSB!  With a simple dipole (my beam seems to have gotten sick from Irene and Sandy) I get good signals on 80, 40, and 20.  Maybe next weekend I will have time to try the upper bands during daylight hours.  But, the signal generator suggests they should be fine.

The ten buck receiver needed ten bucks worth of electrolytics.  And I needed to buy a little 20 buck kit of Bristol Splined wrenches.  (Nobody I thought to ask had a set to lend.)  They were needed because: Another Hallicrafters bit of wonderment is that the setscrews in the control knobs need to be turned with these unusual wrenches that look like, but aren't, hex keys.  Well, I suppose I can say I have the wrenches if I decide to restore another Hallicrafters.  I hear Collins has them too.

I think I mentioned that I had to restring both the band spread and main tuning with real dial cord.  Another three bucks, perhaps.  So, my ten buck receiver is still a bargain at around 40 bucks in all.  And, I had a lot more than 40 bucks worth of fun.  I spent part of the afternoon just listening to the receiver, it sounded so good.  You know how it is when you first listen to a new receiver.

Now, next thing will be to see how it does making contacts with a Knight T-50.  I know the T-50 is not quite QRP.  I probably puts out about 25 or 30 watts.  

This will be about as close to my novice station as I am willing to fall.  The original station had the T-50, but no VFO (which came with the T-50 I have now); but the receiver was an S-38E, which was, (collectors notwithstanding) a piece of crap.  And it's dangerous since it is really one of those transformerless AM radios in shortwave clothing.  No wonder I only made a handful of contacts with it as a novice.  I have no nostalgia for my old Hallicrafters S-38E.  I hear folks recommend operating it with an isolation transformer.  I have a better idea.  Don't plug it in.

I had so much fun with the S-107, though, I am starting to think about restoring an S-108 or an SX-110.

Preston Douglas WJ2V

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Happy New Year! Straight Key Night

 
For the first time in years I got on the air on New Year's eve.  I fired up the HT-37 and Drake 2-B on 20 meters last night right at 0001 UTC  (well, with these rigs I should say GMT!).  There was a moment of stress when, as I was trying to adjust the key, the whole thing fell apart and the little ball bearings spilled out.  Yikes!  It was as if the radio gods were trying to tell me something.  It took me a few minutes to re-assemble my straight key, then I called CQ.  The HT-37 puts out a lot more power than I normally emit,  and it caused the Carbon Monoxide detector to go off, sparking a minor panic among family members.  (See, this never happens with QRP!)  With that resolved I had nice QSOs with K5KFK in Texas, W6VNR in California, and N1WPU in Maine.  This morning I worked WA0ZDE in Missouri.  The old HT-37 was drifting a bit, but Rick said he kind of liked that.  (I put a muffin fan on top of the transmitter -- that should settle it down a bit).   By the way, my key is a bit unusual: it is just a cheapo key, but I have it mounted on the base from a Vibroplex bug.  I never mastered the Vibroplex, and ended up giving the bug parts to HI8G in Santo Domingo -- Gustavo planned on using them to fix another bug that had been given to him years before by Fred Laun (K3ZO). 
 
Rick, WA0ZDE ( who I talked to on 20 this morning) sent me a VERY SKN photo collage (see below).  I see that Rick also tends to hold onto his gear for a long time. 
 
HNY to all!   GL in 14.  73! 
 



Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

SolderSmoke Podcast #157: Peter Parker on Phasing Rigs


SolderSmoke Podcast #157 is available for download.
http://soldersmoke.com/soldersmoke157.mp3

December 27, 2013

-- Santa Report:  Rigol Scope at SolderSmoke HQ.  Kites at VK3YE.
-- Project updates:   Bill's BITX 40/20 build. 
-- Peter finishing up BITX40  (in a big box)
-- BITX 17 (5 watts SSB) works JA, ZD7, ZS!
-- The mystery, elegance, and gentleness of phasing SSB
-- Phasing explained in 1970 ARRL SSB book
-- Phasing SSB: From Hallicrafters HT-37 to SDR
-- The SP5AHT Phasing Rig
-- I & Q for you:  The Binaural Experience
-- Direct Conversion receivers and Software Defined Radios
-- Simple DC receivers plugging into sound cards 
-- The joy of receiver building
-- 144 MHz aircraft bounce (Melbourne to Sydney)
-- VHF Across The Great Australian Bight  

HAPPY NEW YEAR TO ALL!




Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20