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Thursday, November 6, 2014

2014 Bruce Kelley 1929 QSO Party

I'm making progress with this year's 1929 QSO party station. The SW5 works OK but I wonder if the grounding may have gone bad over the years. Nothing in the 1930's SW-5 literature hints at the sort of microphonics and feedback that I'm experiencing. I've tested the bypass caps by substitution and tightened all of the nuts/bolts I find with no change. Running it with an untuned RF stage seems to be the biggest help. Next is powering up my 1928 Hartley.

Pictured is my SW5 at the operating position and Hull Hartley on the window ledge. My Hartley tends to be microphonic because of the tank circuit construction. It can't sit on the operating table because just pounding on the key will be transferred to the transmitter causing the signal to wobble. The window ledge sits on the cinder block house foundation. it shouldn't be going anywhere. I'm using a National 5880-AB power supply (recapped, fused and cord replaced) with the SW5. The regulated power supply is for the Hartley...anything to make the signal as stable as possible. Also part of the station is my Elecraft KX3. The BK recommended operating windows are only 25 KCs wide, just a couple of dial divisions on both the SW5 and the Hartley. The KX3 will be my frequency meter and backup receiver.

Listen to recording of actual Hartley signal:



Friday, October 24, 2014

2014 Bruce Kelley 1929 QSO Party

This year's AWA 1929 QSO Party is only about  1 1/2 months away.
The Feb 1931 QST cover inspired me to pull my SW-5 off the shelf to pair with my Hartley transmitter.

I found feedback within the SW-5 to be a problem. This isn't too bad for casual listening but it is a real problem for  on-the-air operating. Checking through my QST files I found the James Millen Sept 1931 article describing the design process for the SW-3. In it he talks about various shielding options. The SW-5 shielding looks a lot like Millen's first attempt at SW-3 shielding. He described the results as "most disappointing" and "the RF stage oscillated violently". My no holes solution? Turn the tuned SW-5 RF stage into an untuned RF stage. I inserted an RF choke and an antenna coupling capacitor into an empty SW-5 coil form and use it instead of a standard RF stage coil. Now the SW-5 RF stage stays out of oscillation and it still picks up plenty of 80 and 40 meter signals.


It looks like I may be able to use my new QSL cards after all.

Friday, September 12, 2014

Special Event Station K0M

A major focus for my spare time this past spring and early summer has been putting a special event station on the air. We ended up making 214 contacts over five days. See http://radiok0m.wordpress.com/  for the details.

The equipment and focus wasn't particularly vintage or QRP (unless you count the 25 year old Heath SB-1400) but I did try out a new antenna (a MFJ-1777 102' center fed (with window line) doublet) and now I know more about setting up a special event station.

One advantage of a special event station is that there are no contest type rules. You can put as much into it as you wish. It could certainly be used to introduce other local hams to QRP operating or vintage equipment. A 1x1 call can even be reserved at http://www.1x1callsigns.org/ . Fortunately WB4AEJ's posting at  http://forums.qrz.com/showthread.php?444979-Planning-and-Operating-a-Special-Events-Station-2014  covers a lot of the how-tos.

Wednesday, May 28, 2014

Function again wins

80 years ago crystals were expensive. Hams made do with one or two. Ads for the Utah Jr even touted two crystals will cover 160-20 meters. Swapping crystals to QSY up and down the band was not a high priority. The Utah Jr reflects this design philosophy. The one crystal socket is accessible only from the back and sits just in front of the plate loading cap with B+ exposed. Just the other side of the 6L6 is the plate loading coil with the same B+ exposure. Safe operating practice requires one to power down this transmitter before changing the crystal.

Today most hams have transceivers, they expect to hear a response to a CQ on their frequency. If I don't have a crystal plugged that puts me close to a station calling CQ he isn't going to hear my call. Powering down the transmitter to swap a crystal out takes time tempting me to cut corners.

The obvious solution is to extend the crystal socket so that I could change the crystal without digging in to the rig. I ended up building two versions. The cute one shown included 8" of TV twinlead and two crystals sockets wired in parallel. It sat on top of the Utah Jr making it easy to change crystals. The functional one had only  two wide spaced 3" leads running from a male 5 pin plug (that fit the Utah Jr crystal socket) to one crystal socket barely beyond the back of the transmitter. Running with the cute one resulted in a chirpy, harmonic laden signal while the other gave a clean signal. The cute one added about 7pf in parallel with the crystal while the functional one only added about 2pf. Maybe the extra 5pf causes a problem or maybe RF is feeding back via the 8" of twin lead. Either way, function wins over cute.

Thursday, May 8, 2014

Utah Jr Transmitter

The May 1936 issue of QST included an announcement of a new "Audio Power Tube", the 6L6, with a promise of more information in the June issue. By June the new 6L6 was featured as  "a high output crystal oscillator". In the second half of 1936 four transmitter designs in QST used the 6L6. The pace didn't slow down. In 1937 twelve QST transmitter designs used the 6L6. Clearly hams were excited about this new tube.

About this time Utah Radio Products Company in Chicago decided to begin offering kits that used their transformers. The Utah Jr was one of their first products. It was a single 6L6 crystal oscillator with self contained power supply. The Junior design appears to be based upon the "new Jones Regenerative Oscillator" described in the 1937 Frank C Jones Radio Handbook.



Ads featured the Junior as
an exceptional and outstanding value, especially recommended for the beginner and as the nucleus for a more powerful CW or phone transmitter. Experienced hams could even use this as an inexpensive standby or emergency transmitter. At $15.95 (less tubes, meter and crystal) this "professionally styled" 25 watt transmitter was heralded as the biggest bargain in the history of radio. With only two crystals it could cover 160-20 meters. It was the most amazing opportunity ever offered aspiring DXers. It could always added to without junking parts ( All Wave Radio, November 1937, pg 613).
With hype like this how could I pass one up when it was offered to me in a trade?


My Utah Jr was sold in the ARRL auction a few years ago. 
In general it was in pretty good shape with only a single obvious mod. Someone had done a nice job of adding a jeweled pilot lamp to the front panel. Pulling the RF deck revealed additional modifications to change the output to a pi network plus a variety of questionable caps, resistors and RF chokes, but no major problems. The power supply had already been recapped. It just needed a new bleeder resistor and three wire cord.

Restoration consisted mostly of backing out the RF Deck mods. The manual mentions wiring the loading capacitor in series with the antenna. This is needed for low impedance antennas. Given today's 50 ohm coax fed antenna systems this was the one change I made from stock. This then lead to dealing with the restricted loading range limited by the 250 mmf loading capacitor. I changed the coil socket to a five pin socket. This allows one pin to be grounded. Now I can add fixed additional loading capacitance as needed to the plug in coil to get close to 50 ohms. The stock 250 mmf loading cap is then used for the fine tuning/loading.
As an additional change I added easily removed binding posts to the back of the loading cap so that I can play with the fixed additional loading capacitors as needed.

Testing indicates that this little transmitter should do a great job for me. It easily runs 10-15 watts out on 80 and 40 meters and sounds good. For now I'll use it with my HRO Sr.
(My thanks to John Dilks, K2TQN, for his work to post a clean copy of the Utah Jr manual and schematic.)

Addendum, May 31, 2014:
Yesterday both K9LW and K8MRS reported a fine sounding signal. Another vintage transmitter is back on the air.



Thursday, April 24, 2014

Passing the Test

I understand the Maasi people of Tanzania and Kenya have a rite of passage for boys as they become men. Each must journey into the wilderness to kill a lion. Up until a few years ago we hams had a rite of passage. This one dictated by government regulation. Each of us had to journey to the nearest FCC office to be tested.

 Five stressful minutes and five intense seconds...

Six of us were seated around the worn table in the exam room of the FCC office in San Francisco. The window shades were drawn even though it was daytime. No fan could dispel the feeling of nervous tension that hung in the air. I'm sure each of us wanted to be there but we each also wanted the next few minutes to be over. I was no different from the others. I wanted to pass this test so that I could advance as a ham. Without a passing tic mark I'm off the air. To add to the pressure, sitting outside in the waiting room is Vance, my Elmer and new step-father. He had passed this same sort of test almost 30 years before. He was good at this and I wanted to demonstrate that I was good also.

Only the FCC examiner stood. I forget what he looked like. I was worried about the test, not him, but he had the power of a god. He would say if I continued with my hobby. He gave the instructions and reviewed the requirements. I was to demonstrate that I could copy Morse code sent at 13 wpm. He had a machine that had the code etched onto paper tape. Once started, his machine will send this code at exactly 13 wpm for five minutes. It would not stop, slow down or speed up. To pass I had to copy any one minute perfectly. One minute of code at 13 wpm, five characters per word. One minute, 65 characters, in a row, perfectly.
We six each put on our headphones. This was 1967. Ear buds weren't invented yet. These were "cans", two of them, each covering an ear, with a metal springy band across the tops of our heads to clamp them in place. Now I was focused. My world was those cans, my pencil and the government issued lined tablet in front of me.

The machine started. Focus, focus, di di di dahhh, "V", that's an "V", write it down. What was the next character? I missed it. Slow down, wait, you're going too fast. But the machine doesn't wait. One minute, 65 characters, in a row, perfectly , that's all I need, focus, focus. The dits and dahs keep coming. I'm hunched over my paper writing as fast as I can figure out what's being sent. I'm focused only on the sound in my ears. I see only the tablet in front of me. Suddenly "ker thunk". It must have been my sweat. Those headphones, slicked by my own nervous sweat, had slid off my head, falling to the table. Quick, put them back on. What have I lost? Maybe five seconds? Five or six characters? Start over. One minute, 65 characters, in a row, perfectly. But in those few seconds, with that ker thunk, I was finished. I could no longer focus.

I did fail that time but the world didn't end. I had copied enough code to earn my Technician class license. For a while I'd be WA6AVE using a Heathkit Twoer on AM. About six months later, sitting in the San Antonio FCC exam room (and more comfortable with my ability), I passed the code test. Today CW is my mode of choice.




Thursday, April 17, 2014

In The Beginning



I've been a  ham, now, for over 46 years. Hams sort of relate to their calls, their shacks and their radios. I'm no different. 

In the beginning...

I was 15 and a sophomore in high school when I passed my Novice test. The FCC  issued me the call WN6ULH. No one else in the world had that call. It was mine and mine alone. Anyone world wide hearing "WN6ULH" would know it was me at the radio, quite a trip for a 15 year old.

 We lived in Santa Rosa, California and had recently moved across town to a new home. My grandfather, a retired building contractor, remodeled the kitchen for us. He then partitioned off part of the garage for me to use as a shack. He even included the old kitchen counter recovered with plyboard. I had my own work bench and even a built in 3' x 4' table for my station. 

Vance, W6ZZL, helped me find the radios I would use for that first station. In 1967 most ham gear, especially those a 15 year old could afford, had tubes rather than transistors and many were WWII military surplus. Mine were no different. My first receiver, a BC-342, had a "function before beauty"  blockish sort of look that fit the battle field it was designed for but it worked fine for me in that northern California ham shack. The Eico 720 transmitter Vance and I found had great 1960 style with its black low slung cabinet, copper trim and satin finished  front panel.  Used together those two allowed me to work hams all over the US at a time when long distance telephone calls were always expensive.

Some 15 year old boys might have dreamt of getting their first car. I already had my radios. I guess I was, without knowing it, firmly establishing myself as a nerd.

Wednesday, April 16, 2014

A Clotheline Dipole

My Christmas list this year included two Coleman Clothesline/Laundry Reels ( http://www.coleman.com/product/clotheslinelaundry-reel/827E140T#.U07utZmHMR9 ). I replaced the clothesline with 25' of stranded/insulated wire and made up a center insulator with a coax fitting.

Now I have a field configurable 30-10 meter dipole. All I need to do is attach the coax and wire/clothesline reels to the center insulator, roll both sides out to the proper dipole length for the band of choice, lock each leg by wrapping the wire around the tab on the reel and then hoist it up in the air. The wire still coiled on the reels at the two ends of the antenna should not be a problem.

Spring is close here in southern Minnesota. Soon I'll be able to take it out and give it a try.

Thursday, February 20, 2014

Surfing the Web for Radio Reading

We're under a blizzard warning today here in SE Minnesota. 10"-12" of heavy snow is forecast along with winds up to 50mph. My KX3 is in the shop and somehow the power supply project in the basement isn't calling to me. Instead I've been surfing the "net" looking at my favorite sites. Here are some I've found:

Vintage Radio Magazines on line - this includes ones like Shortwave Craft and Radio News. These are great sources of radio/parts/company information and potential projects

Notes on Amateur Radio Transmitter Design, James Millen, 1938

National Radio Products catalog, 1947

Radio Design Practice (mechanical drawings of lots of radio parts including National dials and caps), James Millen and MB Sleeper, 1935

Technical books online - This one includes full scans/PDFs of the 1936 and 1941 ARRL Handbooks, 1938 and 1940 Radio Handbook and the 1959 edition of Bill Orr's Radio Handbook

The VE7SL  Radio Handbook - Steve has posted details many of his projects here. Take the time, also, to go to his 1929 TNT transmitter page and then scroll down to see his photo gallery of homebrew '29 style rig.

ARRL HF Verticals    Links to many QST articles about vertical antennas. Use the sidebar to find articles about other types of antennas.





Monday, February 10, 2014

Boots for my KX3?


My effort to build a relay box so that I can use my grounded grid 572B amplifier with my KX3 has hit a major bump. A few seconds of transmitting destroys the KX3 power amp / final transistors. Did I say major bump?, obviously this is a killer.

My design is straight forward and I use PTT rather than VOX for both CW and SSB so I'm not transmitting when I switch. There doesn't appear to be any shorts between the relay contacts. The problem, I believe, must be the open frame DPDT relay I'm using for bypassing the amplifier. On transmit the amplifier output and the KX3 output are both routed through the relay armature. The two signals are only about an 1" apart for 1.5". I suspect there is a lot of coupling between them. Some of the 90 watts meant for the antenna is feeding back into my KX3. I can imagine this extra power, if it doesn't directly destroy the KX3 finals, could screw up the KX3 final mismatch detection circuitry. I may be running the finals into a load they aren't designed for while the extra RF from the amplifier is causing the mismatch detection circuit to say everything is cool.

The possible solution: a relay designed for RF switching, namely back-to-back Dow-Key relays. Now if I could just tell if the KX3 finals are being stressed I'd be comfortable. I'd hate to blow another set.

I'm afraid this project is going back on the shelf. I'm having plenty of fun with my KX3 barefoot. No need to risk the finals a third time.