The Solder Is Smoking at N6QW!

It is very good to see the solder flowing again in the Newbury Park Laboratories of Pete Juliano, N6QW.  Check out that postage stamp-sized display.

More details on Pete's newest rig can be found on his blog:

http://n6qw.blogspot.com/2016/05/a-new-ssb-transceiver-from-n6qw-with.html

Putting Junk Mail to Excellent Use: Tony G4WIF's Proto-boards

Tony's Version of Audio Section of N6QW's LBS Receiver

Tony Fishpool, G4WIF writes:

I’ve been intrigued by Pete’s matrix pad method. Of course, few of us have the machinery to mill them as Pete does, but etching is a possibility. Now some of Pete’s boards clearly have a lot of noodling behind them. His boards are quite big with little areas of pads and space between. The layout for the whole project has clearly been considered in advance.

I wanted a board that I could make modular, take little time to etch and adapt for the circumstances. These “proto-boards” are the result.

The project is Farhan’s “sweeperino” and one board is for the Si570, and the other the AD8307.

The Si570 board is now complete and working:

The PCB method is pure Chuck Adams. His videos on YouTube describe the toner transfer method better than I could.

The only difference for me is that my glossy paper comes free from travel agent brochures.

Just express a passing interest in Viking River Cruises and you will never pay for PCB paper ever again!

There is a free printing only version of the software I use, so if SolderSmoke listeners want to use the proto-board design, I will happily email them the files.

Kind regards

Tony G4WIF

A 12AU7 Atop a Raspberry Pi

http://makezine.com/2016/05/06/warm-tube-tone-is-just-what-the-raspberry-pi-has-always-been-missing/

I don't know what to say.   One moment I find myself thinking that this could represent "the best of both worlds."   A minute later I'm thinking that this thing is a horrible chimera.  And it has a whiff of audio fool-ism about it, don't you think?  Will it work better with oxygen-free cables and gold-plated fuses? 

Still, overall -- pretty cool.

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).

Farhan's Cool BITX 40 (video)

I especially like the wood base and the transparent front panel.  But we have to send Farhan a D-104!

Check out the video of this rig in action:

https://www.facebook.com/ashhar.farhan/videos/10153914094442107/

Farhan posted:

The BITX40 has a redesigned crystal filter at 12 MHz that contributes to a very clear signal. Note the clarity on SSB and the absence of noise due to the three poles of filtering. This was charminar net on May 2, 2016. I couldn't break-in. Probably because the tiny plug mounted mic was too far away from my mouth.

Un-modifying an S-38 in 1966, and the Urge to Build

Michael mentioned this article in the Comments section under yesterday's post.  March 1966 issue of 73 magazine.  Page 26.  Just click on the images for easier reading.   Or you can find the article here:

http://archive.org/stream/73-magazine-1966-03/03_March_1966#page/n27/mode/1up

More S38 wisdom from 73 here:

http://archive.org/stream/73-magazine-1976-11/11_November_1976#page/n89/mode/1up

That's the November 1976 issue, page 88.

I miss "73".

Hallicrafters S38-E Saved! it is not a "Pig with Lipstick." It Sounds Good! (Video) (And Radio Moscow recordings)

You guys know how it is:  You get tired of struggling with an old piece of gear.  You put it aside, thinking that you might never work on it again.  But it sits there in the corner, sort of looking at you.  A few days or weeks or years pass and you think, hey, I'll take one more quick look at this thing to see if I can get it going.

That's what happened to me this weekend with the Hallicrafters S38-E.  I hooked up the isolation transformer and put a fuse in the primary. I checked the wiring of my rewound antenna coil primary and found that I had connected it wrong.  Duh.   I then found that the antenna tuned circuit tracks fairly well with the tuned circuits in the local oscillator. 

I hooked it up to my 40 meter dipole and fired it up.  As evening rolled around the shortwave bands started to perk up.  The Chinese Broadcast stations were there, as was that fire and brimstone preacher Brother so-and-so.   But then I tuned into Radio Havana Cuba and the guy was talking about homebrew shortwave antennas.  Could it be?  Yes indeed.  It was Arnie Coro CO2KK.  The Radio Gods had spoken!  They clearly had wanted me to get this old rig going.

I still have a few things to do:  I need to fix the front panel light.   I want to put in a three-wire (with ground) AC cord.   Perhaps a real BFO (the original circuit seems to run out of steam with strong SSB signals).  And I need to spruce up the alignment on the 1.7-5 Mc and 13-30 Mc bands.

I think Pete and I may have been too harsh on this old receiver (calling it a pig with lipstick and all that).   It is clearly not a great communications receiver, but it is nice for casual shortwave listening. 

And here is a bonus treat for you guys: Remember Radio Moscow in the bad old days?  Yesterday I found a site with good recordings of some of their 1965 broadcasts.  This is  just what you would have heard coming out of an S38-E in 1965:

http://www.wnyc.org/shows/radio-moscow/listen/ 

1625 Tubes and Si5351 Chips: JH8SST's FB Rig

Peter has been helping Jun JH8SST and other Japanese hams get their Si5351 synthesizers working with various displays.   Jun has had some great success as you can see in the above video.  I really like the combination of old (1625) and new (Si5351) technology.

Jun is a long-time homebrewer who as built some amazing stuff.  Check out the pictures on his QRZ.com page:

http://qrz.com/db/JH8SST

And look at his cool 128x128 TFT display:

Other videos here:

https://www.youtube.com/channel/UCcY94imiTswpjPcfcUIbNcg

KC9KEP's Superhet Receiver with HOMEBREW 455 kc IF Transformers

No store-bought 455 kc IF cans for Big Nick!  FB OM.  Great stuff.

We have featured Big Nick's beautiful work twice before:

http://soldersmoke.blogspot.com/search?q=kc9kep

More of his videos here:

https://www.youtube.com/user/KC9KEP/videos

Be sure to check out his coil winder.

Reduction Redux: Searching for Some Smooth Spin

OK, here is yet another picture of my Mighty Midget's Mate receiver, this time with yet another main tuning dial. I gave up on the large reduction drive on the right -- it worked fine but was very stiff.  I cracked open a smaller version of this very common Japanese-made reduction drive, but in this smaller one I was kind of surprised to find  a Jackson Brothers drive in there.   I now had three of these beauties available -- all of them worked fine but with considerable difference in ease of turning.  I picked the one that was easiest to turn.  

I had to cut the main shaft of the beautiful Hammarlund 35 pf variable cap that I am using. This was dangerous, because of the risk of messing up the delicate bearings.   I stayed out of trouble by putting the tip of the shaft in a vise and then cutting the shaft with a small coping saw.  This prevented any force from being transferred to the bearings.  It worked. 

I was careful to try to line up the shaft and the reduction drive as closely as I could. 

I needed something to serve as the tuning indicator.  I used one of those small CDs that often carry the drivers for cheap electronic devices.  It fit nicely.  A standard sized CD was too big. 

The final element was the knob itself.  I had an old Drake 2-B knob in my junk box (who sent me that?).  It was perfect and added a nice touch of soul to this old-new machine.

I built this receiver in 1998 and when I finished it I thought it was pretty good.  But it is much better now.  It has a nice 455 kc Toyo Crystal-Mechanical filter.  The tuning ranges on 40 and 75 now line up perfectly with the phone bands.  It now has a fuse in the power supply. And the tuning is now SMOOTH.

   

Always Listen to Pete! Second Thoughts on the S38-E

After working a bit on the Hallicrafters S38-E receiver, I am forced to admit that Pete was probably right about this receiver when he warned me that I'd be putting lipstick on a pig.  For those of you who have a sentimental attachment to this receiver, please don't take offense -- I understand.  But while I had one of these as a kid, I never really BONDED with it. That Drake 2B was stiff competition for my radio affection. So I can be more objective about this thing.  And I now think Pete was right. 

Problems: 

-- It is mechanically rickety.  It jiggles around mechanically and, as a result, electrically.

-- The front end is no match for Northern Virginia RFI.  All it has between the antenna and the converter tube is one puny LC circuit.  Not enough.

-- The LO mixer and the LO are stuffed into one 12BE6 tube.  The IF amp and the BFO cohabitate in another tube. In each case there  just seems to be too much going on between one plate and one cathode. 

-- The whole AC/DC transformer-less thing is kind of nuts. You have to get used to TWO ground symbols on the schematic: one symbolizes B- (and is not attached to the chassis).  The other is to chassis ground.  Turns out that my E model is not really a "widow maker" -- they have a 470K resistor and a cap between B- and chassis ground, so the damage you could do to yourself was quite limited.  Still, it is all kind of goofy.  I have an isolation transformer on the chassis, ready to move this receiver into the 1960s if the spirit ever moves me.  KB2WIG commented:  "At closing time, I don't care if the S38 has lipstick."  

As I worked on this thing, I began to realize that the little homebrew 6U8 receiver I have next to it on the bench is a much better receiver.  So I began to lose enthusiasm for putting lipstick on the S38-E.  At least for the moment.  I do like the cool 1950s place names on the S38-E's front panel:

Java
USSR
Vatican
Singapore
Edmonton (!)
Congo
Milan
Iceland
Angola
And of course, the CD (Civil Defense) frequencies. (For when you wanted to do some shortwave listening while ducking and covering. )

But for  now, me and the S38 are on a break. 

A Reduction Drive for the Mighty Midget's Mate Receiver

This morning I put a reduction drive onto the main tuning cap of my 6U8 Mate for the Mighty Midget receiver.  Before I had been directly turning the 35 pf variable cap.   The tuning rate was a bit too high for easy tuning of SSB stations.  This drive went in nicely and it does reduce the tuning rate considerably, but it feels a bit tight.   Is there anyway to loosen up one of these drives?