I admit it. I am not 100% homebrew. I hang my head in shame.

Walter KA4KXX and Mike WN2A and I were recently talking about the degree to which we are 100% homebrew. Both these guys come a lot closer to this goal than I do.  Here is my assessment of my gear: 

I fall far from a state of 100% homebrew grace:  

-- I use commercial power supplies.  I justify this by saying that I could use batteries, and I wouldn't build them. 

-- I use a D-104 with a Tug-8 amp in the base.  I justify this by saying that I COULD homebrew a mic, but I'd just be using a commercial electret element. 

-- My .1 kW amplifier is from a CCI kit.  I find it hard to homebrew 100 watt amplifiers that do not oscillate. Kits make this a bit easier.  

-- I use a K4KIO Hex beam.  I had a homebrew MOXON, but that got destroyed by a Northeaster.  And I have to limit trips up to the roof. Like to zero. (I ask the gutter guy to do this.) 

-- I have a DX-100 and an HQ-100 that I use to check into the Old Military Radio Net on Saturday morning.  I had a DX-100 as a kid, and John Zaruba K2ZA later gave me his dad's DX-100.  That is the one I use. I picked up the Hammarlund HQ-100 in the Dominican Republic in 1993 and have been repairing it ever since.  It is not a great receiver, but it looks good atop the DX-100 and I have a sentimental attachment. 

-- I have an HT-37 and a Drake 2-B that I have had since I was 14 years old. I have a strong sentimental attachment to this gear.  I have worked on most of this old stuff.  

The three SSB dual banders that I am running are mostly homebrew.  The Mythbuster uses a VFO out of the Yaesu FT-101. The 17/12 rig has an LM386 AF Amp. The 15/10 rig has an SBL-1. 

I will try to increase my HB percentage. 

Checking in to the Old Military Radio Net, March 29, 2025

This was a fairly typical session of the Old Military Radio Net. 3885 kHz AM 0500 local on Saturday mornings. (Distant listeners can tune in via WebSDR.) This clip shows W3EMD, N2CQR (me) and, N1SNG. Buzz W3EMD from the Hudson Valley of New York was on with his KWM-1. Normally he uses a BC-348 powered with a Dynamotor. Last week he told the group that someone had COMPLAINED about the noise that his mic was picking up from the Dynamotor. Geez! I told Buzz that we had been commiserating with him about this on the SolderSmoke podcast. Later in this morning's session I heard WU2D, WA1HLR, AJ1G, and others. I reported on an emergency De-Oxit spraying of my HQ-100's band switch, just minutes before net call up. I also noted that I had found a crystal for 3885 kHz; the radio gods have spoken (TRGHS).

Hammarlund HQ-100 Misidentified in 1963 FCC Film

Oh the indignity!  It appears at 7 minutes 16 seconds in this FCC film.  It is clearly an HQ-100, but the FCC subtitles identify it at an HQ-110.  It is clearly an HQ-100 ( the model without the clock). 

https://www.youtube.com/watch?v=LzPIOfpKkRM

As the owner and operator of what must be one of the few remaining HQ-100s, I feel obligated to defend the reputation of this fine piece of shortwave gear.   

How many of you have HQ-100s?  

Why Do Some VFOs Tune More Linearly Than Others?

This has been one of the major complaints about our beloved analog LC VFOs:   The frequency tuning on these circuits is often not linear.  For given amount of VFO frequency dial turn you can get vastly different changes in frequency.  At one end of the tuning range the frequencies are nicely spaced and tuning is easy.  But at the other end of the tuning range all of the frequencies are bunched together.  This is one of the problems that leads some homebrewers to defect to the sad land of "digital VFOs." 

But wait.  It appears that the old designers found a solution to this problem.  Just look at the tuning dial of my HT-37.  The frequencies are all spaced out evenly.  How did they do that? 

I had been thinking that this success may have resulted from Hallicrafters' engineers using the series-tuned Clapp circuit.  Here the main frequency determining element is a series-tuned LC circuit and not the parallel tuned LC circuit that we see in the more commonly used Colpitts circuit.  

But hold on -- how could that be?  The frequency bunching problem that we attributed to the Colpitts circuit must also exist in the Clapp, right?  I went back to SSDRA where there was a good discussion of Colpitts and Clapp VFOs.  The advantage of the Clapp was said to be in its use of a larger value coil which helped minimize the effects of stray inductances.  But there was no mention of the Clapp offering improved linearity in tuning.  

I have in front of me two transceivers:  The Mythbuster uses a 9 MHz Clapp circuit (see below).  The 17-12 rig uses a Colpitts Circuit.  I checked the tuning linearity of both.  Both appeared quite linear in tuning, with no real difference between the two.  

Then I looked at the tuning capacitor in the Mythbuster 17-12 rig.  It came out of an old Hallicrafters transmitter, probably the HT-44.  I looked closely at the stator and the rotor plates.  Both are curved.  I'm guessing that this may yield a more constant change in capacitance for a given movement of the main tuning dial.  

Next I opened up the VFO on the Mythbuster.  (It is the VFO from an old Yaesu FT-101.)  I couldn't see the stators very well but it appears that their shape is different from the square shape we often see in variable capacitors.  Could it be that this variable capacitor was also made to provide linear tuning?  

Back in 2013 Norm Johnson wrote about all this in the Antique Radios.com forum: 

A capacitor that has uniform increase in capacitance with rotation will have the stations at the high end of the band squeezed together. Another type known as the straight-line frequency variable capacitor has, as you might guess, a characteristic that gives even spacing of frequencies with shaft rotation. These were popular in the 1920's but weren't very good for superhets where you needed to have a dual section capacitor that would tune both the RF and local oscillator, and have them track each other properly. The midline variable capacitor is more compatible with a superhet, and easier to make both sections track properly. This is the type that you see in most receivers from the late 1930's to the end of the tube era. They don't have quite the equal spacing between stations across the band that the old straight-line frequency caps had, but they're much better than the variables that change capacitance linearly with rotation.

I wrote an online calculator that helps in the design of the tuning. It shows what frequency range you'll get with a specific type of variable capacitor, including the effects of padder and trimmer capacitors. It also displays a dial scale that shows how the frequencies are lined up accross the dial.
http://electronbunker.ca/eb/BandspreadCalc.html

Steve W6SSP also provided some really good info back in 2013: 

There are three types of open, variable plate caps;
SLC= straight line capacitance where the capacitance varies linearly,
these are the most common and have half-circle plates
SLF= straight line frequency where the plates are tapered to allow
for linear tuning of the frequency
SLW= straight line wavelength, you get the idea...

SLF and SLW caps have oblong plates.

The effect on tuning a receiver can be dramatic. One example is the
Hammarlund SP series of receivers where the ham bands are very
compressed at one end of the tuning range. They used SLC caps
in the VFO. On the other hand rigs like the Kenwood TS-520
and FT-101 series have linear tuning across each band. These use
SLF variable caps. Most old 1920's battery radios used SLW
where stations were identified by their wavelength.
Steve W6SSP

These two variable caps came out of my junkbox.  Both are Eddystones, made in England.  My guess is that the one on the left is SLF.  But could the one on the right (out of an old regen) be SLW?   

The Drake 2-B also has perfectly linear tuning.  I looked at the manual:  "The tuning condenser is of special design..."   I'm guessing that they used an SLF variable capacitor. The 2-B had no need for ganged capacitors -- the "preselector" was tuned via a separate front panel control. 

I looked at the tuning dials on my Hammarlund HQ-100 receiver.   It is fairly linear in its tuning, but not as linear as the HT-37 or the Drake 2-B; on all of the tuning ranges the frequencies seem to spread out a bit at the lower end.  My guess is that Hammarlund used the midline variable described above by Norm Johnson.  The HQ-100 did use a ganged variable cap, with one section tuning the RF amplifier and the other tuning the local oscillator. 

Mythbuster on the bottom.  17-12 rig on the top

TRIGGER WARNING: Solid-Stating Old Tube (Thermatron) Gear (Including -- GASP -- R-390As)

Look at that.  Well, maybe some of you shouldn't. (I'm thinking of you Grayson.)  I found the Charles Smith YouTube channel while innocently looking for ideas on how to solid-state the HT-37 VFO assembly I recently bought on e-bay.  Charles Smith has some really great ideas in this area.  He solid-stated a Heath VF-1.  But he took it all to an extreme when he solid stated an R-390A.   Take a look at how he built the replacements for the thermatrons:  He used those plastic wall sockets that you screw into sheet-rock when you need to hang a picture.  This is real genius. He used the tube filament lines to carry DC to these new sockets. 

R390A Solid State Conversion Video #1:  https://www.youtube.com/watch?v=xhWzX874wYo

Charles Smith's YouTube Channel 

https://www.youtube.com/channel/UCpfh8gxL64qd22RaNPR-QFw/videos

He has videos on the HQ-170 (DEAN:  Just say NO!) and the SP-600.  He also covers the HQ-110, which is uncomfortably close to my HQ-100.  

Who is Charles Smith?   What is his callsign?    Charles Smith is KV4JT.  Here is his QRZ page: 

https://www.qrz.com/db/KV4JT

He has some great humor and wisdom in his videos: Procedures that are difficult or more trouble than they are worth are called "bugger-bears."  He advises that if your IF cans are stuck, you should "find a way to unstick them!"  Indeed you should!  He builds a cool jig to hold the IF section of the R-390A while you are working on it.  He provides similar protection (with two long screws) to the VF-1.  

Even though some of you will have to go to therapy after seeing all this, I say THREE CHEERS FOR CHARLES SMITH! 

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

HF Bandsweep with the Hammarlund HQ-100 (video)

It has been a while since we last did a bandsweep.  Too long.  Here is one using my recently fixed up Hammarlund HQ-100.  Repair details are in recent videos. 

For this bandsweep we cover most of the HF band and even briefly dip down into the AM broadcast band: 

Demonstration of the Hammarlund HQ-100: Radio Marti, 40 meter AM, 40 Meter SSB, 40 meter FT-8, 40 meter CW with and without the Q multiplier, classical music on WRMI, WFAX 1220 kHz AM, WWV 20 MHz, CB!, 17 meter SSB, the 20 meter BS position, the effect of AVC and the Noise Limiter, SSB with the internal BFO and with the Q multiplier as BFO. CW with the internal BFO AND the Q multiplier. 

Be sure to subscribe to the YouTube channel.  

W1VD's Boatanchor Receiver Tests

I've been trying to get more rigorous in my evaluation of receiver performance.   My HQ-100 is tuned to Radio Marti, and it sounds great.  But how great is it really?  And what about all the receivers and transceivers I have built?  How good are they?  

Our friend Dean KK4DAS is about to start the rehabilitation of his dad's old HQ-170A.   A search for that receiver led me to Jay Rusgrove's very interesting measurement and analysis of old tube type radios.  Jay's results appear in the links below.  More important is his very clear description of how the tests were done and what the results mean (link below). Also included is one link showing a discussion of Jay's work.  

Jay notes: 

The decision of which boat anchor receiver(s) to own is seldom based on performance alone. A combination of favored manufacturer, period of manufacture, features, collectability or even just 'looks' often rank higher on the priority list than receiver performance. Even if one were interested in performance specs much of the available information is subjective as few receivers manufactured prior to the mid 70s have undergone standardized testing. Hard data on minimum discernable signal (MDS), blocking and two-tone IMD dynamic range is interesting to some operators and important in an historical context as it shows the progression of receiver development.

Jay designed the very first real transmitter that I homebrewed (The VXO 6 Watter from QRP Classics). Jay has been mentioned many times in the SolderSmoke podcast and blog:    

Jay's results:   http://www.w1vd.com/BAreceivertest.html

Jay's methods:  http://www.w1vd.com/Receivermeasurementbasics.html

Discussion: https://www.antiqueradios.com/forums/viewtopic.php?t=96872

Troubleshooting and Fixing Old Faults in my Long-Suffering Hammarlund HQ-100 (Part 2) (video)

Work continues on my old Hammarlund HQ-100. I give background on the rig and explain the electrical trauma it likely suffered. Following Dave K8WPE's dictum that we can still learn a lot from old receivers, I dug into this one. I wanted to fix a long-standing S-Meter/AVC problem. This led me to an interesting troubleshoot, with at least one "waste of time" detour. Eventually I found the fault in one of the coils in the grid circuit of the RF amplifier. The coils had been smoked years ago, perhaps by a lightning strike. I came perilously close to permanently losing 10-30 MHz. But I figured out how to fix the smoked coil. So my S-Meter/AVC problem was fixed. I really like listening to this thing. There is still a lot of nice material on the SW bands. There are some very nice broadcasts in Spanish. Please subscribe to my YouTube channel.

You can see where the coil burned. Wire remained intact, but the insulation burned creating a Primary to Secondary connection.

I just very carefully lifted one of the coils way from the other, eliminating the unwanted connection.

Here's my homebrew "RC Printed Network" Z2 module. This was unnecessary -- the original was good. I put the original back in.

Electric Radio magazine recently ran a two part series on the HQ-100. I have ordered these issues of the magazine.

Electronics Manufacturing in New York City -- Limor Fried and Adafruit (video) -- "TRUST YOUR TECHNOLUST"

The Radio Gods seem to be directing my attention to my hometown: New York City.

I was recently in the city, observing the placement of various IBEW - WYKSYKDS stickers.  And as I work on my old Hammarlund HQ-100 I note that both the HQ-100 and I may have been produced on Manhattan island at about the same time (me definitely, but the HQ-100 may have been built in Mars Hill NC). 

This morning Jim W4JED reminded me that Limor Fried, MIT Engineer and founder of Adafruit,  is producing a lot of amazing electronics items right in NYC, on Manhattan Island, down in Chelsea.  Thanks Jim.  FB Limor!  

Watch the above video.  I really liked the sign Limor has above her workbench: 

"TRUST YOUR  TECHNOLUST."  

 Indeed.  Back to the HQ-100. This IS a case of technolust.  I'm not quite satisfied with the alignment.  And it bugs me.  I technolust for perfect alignment.    (Steve Silverman -- I think we should add technolust to the SS lexicon.) 

SolderSmoke Podcast #237 is available: TV Show! No! W9YEI's 1939 TV. 1712 Rig. HQ-100. New SDR Rig and Book. JF3HZB's VFO Digital Dial. FIELD DAY! PSSST. MAILBAG

SolderSmoke podcast #237 is available:  http://soldersmoke.com/soldersmoke237.mp3

Travelogue -- New York City!  Stickers!
And about that trip to Los Angeles for the SolderSmoke Cable TV show... 

Well, it fit in well with SolderSmoke's UNFORGETTABLE appearance on the Oprah book club.
And TechieTatts? Daughter worried about listeners rushing to get tattoos -- A risk we were willing to take.

https://in.pinterest.com/padmakumar10/techie-tatts/

This episode is sponsored by PartsCandy.  GREAT test leads: https://www.ebay.com/usr/partscandy

Bill's Bench

Tracking down Johnny Anderson's 1939 or 1940 homebrew TV receiver.

https://soldersmoke.blogspot.com/search?q=Anderson
Working with Joh DL6ID.
Jean Shepherd's January 1973 description.
FlickLives web site and Steve Glazer W2SG have lots of info on Shep and his friends.
Internet allows us to look at TV articles that were being published.
We've concluded: Probably 1939 or 1940, using an RCA 913 1 inch CRT tube. 

Lots of ideas from IRE Journal, QST, and Gernsback magazines.
Quite an achievement! Amazing how much pre-war TV progress there was.  

17-12 rig
All boxed up and working DX!
Figured out how to display both 17 and 12 on the same LED. https://www.youtube.com/watch?v=kAmmFZyFu8w
Drain protector for speaker cover. Copper tape to cover horrible cabinet making.
I think I need a Hex Beam.

Hammarlund HQ-100
Needed some maintenance.
I started to look more closely at it.
Got the Q-Multiplier to work -- it really adds a lot on CW.
Makes me feel guilty about all the QF-1s...
Using the 100kc calibrator with a 455 kc crystal as a BFO,
keeping Q multiplier below oscillation point.
Moved the BFO switch to the front panel. Helps a lot.
Need to fix the S-meter AVC circuitry.
Much more sturdy than the S-38E.
S-38E 1957-61 $54.95 5 tubes.  AC/DC.
HQ-100 1956-60 $169  10 or 11 tubes.  Power supply,  regulator.
You get what you pay for.  

Pete's Bench

Jack Purdum and Al Peter's new SDR rig and book (featured on the SS blog Amazon ad).
JF3HZB's beautiful digi VFO.
Backpack antenna for Field Day?  
Pipsqueak Disaster -- Too simple?
Peashooter Eye Candy.
Build Something Different.

MAILBAG

James W0JKG CBLA -- Others are building MMM too!
SM4WWG // Jörgen  Wonderful message.  Joined GQRP.  No longer "wrong."
Dennis WC8C Libraries for Max2870 board.
Jack NG2E  Progress on the Right to Repair movement. 
Jim K9JM  Someone cutting into our business with Solder candles!  
Chuck  WB9KZY Correctly identified the location of the IBEW sticker.  As did Dan Random.
Dave Bamford (who lives nearby) suitably impressed. 
Farhan wrote to us about a video on Don Lancaster.  Homebrew keyboards!  Yea!
Dean KK4DAS  QRP to the Field.  HB2HB 40 SSB   QRP  I feel virtuous.  
Todd K7TFC likes my ingenious use of the drain screen as the speaker protector on the 17-12 rig. 
Todd  had good thoughts on granular approach to homebrewing as seen in the Don Lancaster video.
Lex PH2LB HORRIFIED by my reverse polarity protection circuit.  This is a touchy subject! (as is WD-40!)
Rogier PA1ZZ sending great info on SWL and numbers stations.
Jesse N5JHH -- The guy who made the IBEW stickers -- Liked the NYC stickers. 
Steve N8NM has a new antenna article on his blog: https://n8nmsteve.blogspot.com/
Randy AB9GO Agrees -- Can't GIVE old 'scopes away. 
Dino SV1IRG Liked the 17-12 rig videos. 
Steve Hartley G0FUW Murphy's Law of Enclosures. 
Ralph AB1OP FB on the 17-12 Rig. 
Roberto XE1GXG --Our correspondent in Guadalajara. Petulant, irritable people on the computer scene.

Have some gear looking for a good home:   Tek 465 'scope from Jim AL7R W8NSA.   SBE Transceivers.  Windsor Signal Generator.  Let me know if you are interested and can either pick up or arrange shipping.  

John Anderson W9YEI Homebrew Hero

Working On My Old Hammarlund HQ-100 (Part 1)

I like this old receiver, with all its shortcomings.  I picked it up in the Dominican Republic in 1993 or 1994.  I've been using it on AM with my K2ZA DX-100.   It needed some contact cleaner, and I took the opportunity to work on a few of the circuits that were getting kind of decrepit. 

I came to a new understanding of -- and appreciation for -- the Q-multiplier.

While of similar vintage, this receiver is MUCH nicer than the Hallicrafters S-38E: 

S-38E 1957-61 $54.95 5 tubes.  AC/DC, kind of flimsy. 

HQ-100 1956-60 $169  10 or 11 tubes.  Power supply,  regulator,  much sturdier construction

You get what you pay for.   

 In Part II I'll show you how this thing sounds and what it is like to use it for SWL, CW, SSB and AM.