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Wednesday, June 22, 2022

Hammarlund and Homebrew Heroine: Janis AB2RA, HQ-100 Filter Cap Question

 

I was searching for Hammarlund HQ-100 wisdom when Google pointed me to the Electric Radio articles of Janis AB2RA.  They were in  ER #380 and #381 (February and March 2021).  Lots of good stuff  in there.  

This morning I happened upon a 2014 SolderSmoke blog post (as you do) about my Tuna Tin 2. Turns out that Janis was my first contact with this rig.  And she too was running a homebrew rig. TRGHS. 

I continue to work on my HQ-100.  The AC hum is getting worse so I have ordered a replacement capacitor can from Hayseed Hamfest.   But I was a bit confused about which cap to order.  Hayseed has two caps listed for the HQ-100 -- one (it seems) for the early model of this receiver and one for later models.  Is that right?  Did Hammarlund update the power supply to add filter capacitors?  Take a look: 

Dean KK4DAS is getting ready to work on his dad's HQ-170A.  He too will find lots of wisdom and tribal knowledge on Janis's wonderful web site.  

Her main page: http://www.wireless-girl.com/  (with a vast amount of technical info available through the links on the upper left side of this page) 

About Janis: http://www.wireless-girl.com/AboutMe.html

Thanks Janis!  

The Original Wireless Girl

Tuesday, June 21, 2022

Summer Solstice -- EITs. Solar Tsunamis. Strange Falcon 9 Spirals Seen in New Zealand

 

Forbes has an interesting article that may help explain the poor Cycle 25 propagation that were talking about in SolderSmoke podcast #238: https://www.forbes.com/sites/ericmack/2022/03/28/an-increasingly-active-sun-is-now-producing-solar-tsunamis-and-sending-flares-our-way/?sh=613e1dd1fbfd 

And Space Weather website has an interesting piece about some really strange SpaceX Falcon 9-related phenonmenon: 

Monday, June 20, 2022

QRP Labs HQ Tour


Really cool to see Hans describe his QRP Labs workshop in Turkey.  Lots of soul in that worshop.  Thanks Hans.  

 And here is a 2022 Turkish media interview with Hans and his team in the workshop:  

Sunday, June 19, 2022

A Great Book on Oscillators (Analog LC Oscillators) by John F. Rider (Free!)

 

Thanks to Peter Parker VK3YE for alerting us to this wonderful 1940 book.  John F. Rider -- a real hero of electronic literature -- does a great job in discussing the practical aspects of oscillator circuits. 

This excerpt from Rider's foreword gives a sense of the approach taken in this book: 


The book covers a lot of material.  In addition to the standard oscillator circuits, he discussed multivibrators, relaxation oscillators and much more.  There is a chapter on magnetostriction in which he shows that this property is the basis for crystal oscillators AND the mechanical filters that we are familiar with.  In fact he seems to take what we would consider a mechanical filter and put it in the grid circuit of a tube to make an oscillator. 

He discussed the modulation of oscillators. He describes the Heising modulator that caused young Jean Shepherd so much teenage heartache.  

Download the book here: 

Friday, June 17, 2022

Video of SolderSmoke #238


For details and audio podcast see: 

SolderSmoke Podcast #238 -- SolderSmoke Shack South, Cycle 25, Chiquita Banana Radio, RCA, HQ-100, Mate Mighty Midget, Sony SWL RX , Mailbag

SolderSmoke Podcast #238 is available:  http://soldersmoke.com/soldersmoke238.mp3

TRAVELOGUE:  

Cathartic decluttering:  Bill preparing for future winter travel to Dominican Republic.  Will build SolderSmoke Shack South.  Dividing everything up:  Rigs, parts, tools, supplies, antennas, test gear.  Everything.  

OUR SPONSOR:  Parts Candy.  
https://www.ebay.com/usr/partscandy  Premium quality test leads! Hand cut, hand crimped, hand soldered, these will become your new favorite test leads GUARANTEED!

PETE'S BENCH:

-- Cycle 25 better? – Out here on the left coast – it is not evident
-- Chiquita Banana and the US Navy in early ‘wireless” operations.  Why RCA was created by the US Navy in 1919.
-- Update on the MAX2870 –someone has written the code to make it work with the Raspberry Pi and the QUISK SDR software
-- Field Day prep

SHAMELESS COMMERCE DIVISION:
 
Bill needs your help:  
-- Please watch his YouTube videos.  The longer the better!  Success based on hours watched. Great to have on while you are working in the shack. Just go to YouTube and search for the SolderSmoke channel. Or:  SolderSmoke - YouTube
-- Please put links to the SolderSmoke blog on your websites and blogs. 
-- How to USE the SolderSmoke Blog: Propagation, shopping, other sites... 
-- Please put comments under the articles on the SolderSmoke blog.  We like comments and dialogue. 

BILL'S BENCH:

-- Repair of the Sony ICF SW1 shortwave receiver.  Bad electrolytics.  Number Station receiving device? 
-- HQ-100   Q-Multiplier. BFO Switch. AVC.  Noise Limiter limitations.  Dave K8WPE: Old Radio Lessons.
-- MMMRX: Detector circuit. Alignment. Muting. On the air (40 AM with DX-100) 

MAILBAG: 

-- Bob Crane W8SX -- Great interviews at FDIM. On the SolderSmoke Blog. Thanks Bob! 
-- Dave Bamford W2DAB -- Stickers on the Upper East Side of Manhattan.  FB Dave! 
-- Farhan VU2ESE:  LADPAC software now available through W7ZOI' site.  
-- Lex PH2LB: Stickers in a Netherlands pub.  
-- Dave K8WPE Michigan Mighty Mite links.  Old Smoke idea. On the SolderSmoke blog. 
-- Rich WB4TLM was in the electronics class of CF Rockey W9SCH. FB. 
-- Dean KK4DAS Working on  his dad's HQ-170A. VWS maker group on mixers. 
-- Grayson KJ7UM -- Mixology article in ER. 
-- Pete Eaton -- Farhan's new analog rig: Daylight again!  Standby for more info from Farhan. 
-- Will KI4POV New HB Al Fresco single conversion superhet.  FB. 
-- Alvin N5VZH. Shep's "I Libertine."  Yes.  I laughed, I cried,  It changed me. 
-- Chuck KF8TI.  Mr. Wizard!  
-- Steve N8NM on the mend after some routine maintenance. 
-- Ben AB4EN is listening and likes the podcast -- Thanks Ben. 

May 1939 QST


Thursday, June 16, 2022

Watch Mr. Wizard! 1952 Program on Electromagnetism. And more! (video)


Wow.  This is a very thought provoking program.  It is kind of like "Mr. Roger's Neighborhood," but with science. The lessons provided by Mr. Wizard are really good, but one shudders to think about doing the these experiments with kids (or even with adults!) in today's world.  Here are a few of things that would cause trouble today:  

-- Liquid mercury.  
-- A big power supply. ("Here Willy, you hold the positive terminal.") 
-- Even the sprinkling of iron filings would probably require masks at a minimum.  
-- In the end, letting poor Willy drop to the floor when Betsy turns off the electromagnet that was holding his swing in the air.  
-- And of course, poor old Mr. Wizard's affinity for the kids would stir suspicions. 

We also see a sad and very early example of the influence of advertisers and what they call today "product placement."  Note the fairly obvious plug (via Morse Code!) for breakfast cereal.  In the credits you will see that the program was sponsored by "The Cereal Institute."  What next kids?  Cigarettes? 

But there is a lot of virtue in this program:  The development of the telegraph key, Morse Code,  CW sidetone.  Unlike many of the Box Top Extras of today, young Betsy was not afraid to wind a coil.   

We should all embrace the spirit of Mr. Wizard.  We are, after all, the International Brotherhood of Electronic WIZARDS!  These experiments reminded me a lot of the Trivial Electric Motor that my son Billy and I made when he was around Willy's age (thanks for the idea Alan Yates).  

Thanks to Chuck KF8TI for alerting us to this show.  Chuck says this program was an early influence on him, and was one of the things that provided a connection between the theory he was learning in college and the real world of electronic devices. 

Many more great programs like this can be found on Mr. Wizard's YouTube Channel: 
https://www.youtube.com/user/MrWizardStudios   Please let us know if you find other videos (on this channel or elsewhere)  that will be of special interest to the IBEW. 

Finally, color TV in 1952?  That seems a bit early for color.  What do you folks think was happening here? 

Tuesday, June 14, 2022

Hans Summers G0UPL Wins FDIM 2N2222A Power Out Challenge -- 4.1 Watts from Two 2N2222As


Farhan told me how cool this was.  And he was right.  It looks like a lot of fun.  Congratulations Hans! 

 

Monday, June 13, 2022

SolderSmoke FDIM Interview with Keith W. Whites -- Teaching Electronic Design to EE students using a QRP Transceiver designed by Wayne Burdick


When I first listened to Bob Crane's interview at FDIM with Keith Whites, I thought of the book "The Electronics of Radio" out of CalTech by David Rutledge.  Keith Whites told me that the difference between his effort at University of Kentucky was that Rutledge's course was designed for freshmen at Cal Tech, while White's course was aimed at Juniors and Seniors.  

I told Keith Whites that I had struggled to understand the Gilbert Cell and the NE602, the device that lies at the heart of the rig used in both courses:  The NE-602 Gilbert Cell Mixer used in Wayne Burdick's NORCAL 40A. Here is how I came to understand the device:  https://soldersmoke.blogspot.com/2021/11/how-to-understand-ne-602-and-gilbert.html

Here is Bob Crane's interview:  http://soldersmoke.com/2022 Whites.mp3

Here the slides that Keith used at FDIM: http://soldersmoke.com/2022 Teaching NorCal40A.pdf

Keith's students obviously got a lot out of this course.   Keith has kindly offered to make his course notes available to those who need them. 

Thanks to Bob Crane, Keith Whites, David Rutledge and Wayne Burdick. 


Saturday, June 11, 2022

Putting the "Mate for the Mighty Midget" Back to Work -- With a DX-100 on 40 Meter AM

After working on it for a while I got so fond of my old Hammarlund HQ-100 that I moved it from the AM/Boatanchors operating position over to a more convenient spot right next to my computer.  This left a big gap on the receive side of the AM station.  

I briefly put my HRO-ish solid state receiver above the DX-100, but I'm afraid that receiver needs some work.  More on that in due course. 

I thought about putting my SOLID STATE Lafayette HA-600A atop the thermatronic DX-100, but this just didn't seem right. The Radio Gods would NOT approve. 

So I turned my attention to the Mate for the Mighty Midget that I built in 1998 and have been poking at and "improving" ever since

This receiver worked, but not quite right. It received SSB stations well enough, but when I turned off the BFO I could no longer hear the band noise. I wasn't sure how well the RF amp's grid and plate tuned circuits tracked.  And I had serious doubts about the detector circuit that Lew McCoy put in there when he designed this thing back in 1966. 

As I started this latest round of MMMRX poking, I realized that I now have test gear that I didn't have in 1998:  I now have a decent oscilloscope.  I have an HP-8640B signal generator (thanks Steve Silverman and Dave Bamford).  I have an AADE LC meter. And I've learned a lot about building rigs. 

FRONT END TRACKING

The MMRX has a tuned circuit in the grid of the RF amplifier, and another in the plate circuit of the RF amplifier.  There is a ganged capacitor that tunes them both.  They need to cover both 80/75 and 40 meters. And they need to "track" fairly well:  over the fairly broad range of 3.5 to 7.3 MHz they both need to be resonant at the same frequency.  

McCoy's article just called for "ten turns on a pill bottle" for the coils in these parallel LC circuits.  The link coils were 5 turns.  No data on inductance was given.  Armed now with an LC meter, I pulled these coils off the chassis and measured the inductances of the coils.  I just needed to make sure they were close in value.  They were: 

L1 was .858uH L2 was 2.709         L3 was .930uH  L4 was 2.672

Next I checked the ganged variable capacitors.  At first I found that one cap had a lot more capacitance than they other.  How could that be?  Then I remembered that I had installed trimmer caps across each of the ganged capacitors. Adjusting these trimmers (and leaving the caps connected to the grid of V1a and V2A, I adjusted the trimmers to get the caps close in value.  I think I ended up with them fairly close: 

C1: 63.77-532 pF          C2 64.81 -- 525.1 pF

I put the coils back in and checked the tracking on 40 and on 80/75.  While not perfect, it was close enough to stop messing with it.  

DETECTOR CIRCUIT


I've had my doubts about the detector circuit that Lew McCoy had in the MMMRX.  In his 1966 QST article he claimed that the circuit he used was a voltage doubler, and that this would boost signal strength.  But I built the thing in LT Spice and didn't notice any doubling.  And consider the capacitors he had at the input and output of the detector:  100 pF.  At 455 kHz 100 pF is about 3500 ohms.  At audio (1 kHz) it is 1.5 MILLION ohms. Ouch.  No wonder years ago I put a .1 uF cap across that output cap just to get the receiver working. 

Scott WA9WFA told me that by the time the MMMRX appeared in the 1969 ARRL handbook, the second "voltage doubling" diode was gone, as were the 100 pF caps.  Now it was just a diode, a .01 uF cap and a 470,000 ohm resistor.  I switched to the 1969 Handbook circuit (but I have not yet changed the 1 meg grid resister to 470k -- I don't think this will make much difference).  Foiled again by a faulty QST article, again by one of the League's luminaries. 

6U8s out, 6EA8s in 

We learned that the 6U8 tubes originally called for by Lew McCoy are getting old and not aging well.  So I switched all three to more youthful 6EA8s.  This seemed to perk the receiver up a bit. 

MUTING from the DX-100

My K2ZA DX-100 has a T/R relay mounted in a box on the back of the transmitter.  When the Plate switch goes up, it switches the antenna from receiver to transmitter.  The box also has a one pole double throw switch available for receiver muting.  I put the common connection to ground, the normally connected (receive position) connect the ground terminal of the AF output transformer to ground -- it is disconnected from ground on transmit.  The other connection (normally open) is connected to the antenna jack -- on transmit this connection ground the receiver RF input connection.  These two steps mutes the receiver very nicely. 

Replacing Reduction Drive

Over the years I have had several different reduction drives on the main tuning cap.  I had a kind of wonky Jackson brothers drive on there that needed to be replaced.  I put in a new one -- this smoothed out he tuning considerably. 

Ceramic Resonator

I never could get McCoy's 455 kc two crystal filter to work right.  So at first I made due with the two 455 kc IF cans.  This made for a very broad passband.  Then I put a CM filter in there.  This was more narrow, but with a lot of loss.  There may have been others.  But the filter spot is currently held by a 6 kHz wide ceramic filter.  This one is my favorite so far. 

Digital Readout

When I was running the DX-100 with the Hammarlund HQ-100 I built a little frequency readout box.  The box was from a Heath QF-1 Q multiplier (I am sorry about this).  The readouts are in Juliano Blue and come via e-bay from San Jian.  I now have it hooked up to the DX-100's oscillator.  I haven't tapped into the MMMRX's oscillator yet. 



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