National Dial and Gearbox Problem Resolved

Thanks to all who offered advice and assistance. With help from you guys — and especially from Pete Juliano N6QW — I think I have this fixed.

 Pete was right — the problem was really with the variable capacitor. The one I was using was kind of stiff and irregular in its motion. I found another one in the junk box that was easier to turn (it has one set of ball bearings). This fixed most of the problem.

 I also spent more time making sure the shaft of the cap lined up perfectly with the shaft of the gear box. This also helped a lot.

 I realize now that some of the “stickiness” that I occasionally feel while tuning may be coming from the dial — not from the gear box. It looks like my dial took a hit that slightly bent one portion of it. It seems that the numbers have a bit of trouble clicking over on that portion of the dial. Some lubricant may help there. But I can live with it.

 The receiver now tunes very smoothly and I can go right back to a frequency and find the signal exactly where I left it. There does seem to be a very slight difference depending on whether I “approach from above” or “approach from below” — but this is not a big deal.

 Check out the pictures of the receiver and the VFO. Note the “cardboard from a coat hanger” coil form. The winding is held in place with nail polish varnish. I had planned on having the variable cap, the coil , and the associated fixed caps all in a box for better thermal stability, but the VFO is very stable even without the box. I have the VFO running 455 kc ABOVE the signal frequency. It runs from about 7455 kc to about 7800 kc. I could have set it up to run 455 kc BELOW the signal freq. That would have made it a bit more stable (it is easier to attain VFO stability at lower frequencies) but VFO is so stable that I probably won’t mess with it. I followed DeMaw’s rules: Physical stability, NP0 caps. For the NP0 caps, put several of them in parallel to get the desired capacitance value. Keep heat-producing active components away from the coils and caps.

Thanks again to Armand WA1UQO for giving me this amazing piece of radio history. And thanks to Tim Sutton for the big box that holds this receiver.

James Millen knew what he was doing. See: http://www.isquare.com/millen/millen-page.htm

M0KOV’s Real Life Dilbert Moment — His Mom Took Him to the Doctor

M0KOV’s BITX
Dilbert’s mother took him to the doctor because of ham radio. Jean Shepherd’s date said that Shep’s mother should “take him to a doctor” (he was obsessing over his Heising modulator.) And now we learn that Steve M0KOV was hauled into the doctor’s office because of his “obsession with electronics.” You are in good company Steve. The Knack diagnosis is confirmed.

From Steve M0KOV:

Just watched young Dilbert at the doctor’s surgery.

Although I was late getting my ham licence, I’m sure that I fit the standard knack victim mould. I built my first radio at the age of 10 and even before then I preferred to be bought batteries, switches and lamps rather than sweets. Within a couple of years my small bedroom comprised of a bed, somewhere to throw my clothes and an electronics work bench. The bench and floor were completely covered with half built electronic projects, ex military radios, tools, my beloved old Heathkit oscilloscope and the rest.

Now, my true Dilbert moment. I remember being in the family doctors surgery and my mother was discussing my inability to get to sleep (a perfectly normal ailment for a 13 year old male). She was voicing her concern that it might be my obsession with electronics, and it was all going round in my head and keeping me awake. Funny, later in my life she never seemed to be bothered if the worry of studying or exams kept me awake.

Thanks for another great podcast.
73 de Steve M0KOV

SolderSmoke Podcast #209 SKN, Old Rigs, Movie Review, Safety Tips, Mail Bag

SolderSmoke Podcast #209 is Available:

13 January 2019

 http://soldersmoke.com/soldersmoke209.mp3

An HT-37 “With Presence!” Even on CW! A Straight Key Night Story
Saving a much-loved HT-37
Drake 2-B Alignment
Tweaking the Mate for the Mighty Midget
Fixing a Deaf DC Receiver
A Wobbly National HRO-ish Gear Box
Minimum Discernible Signal Tests
Pete’s Festive Holiday Transceiver in a Bottle

 Movie Review: “First Man” Neil Armstrong goes to the moon.

Safety Tips for 2019: Fuses, Hard Drives, Flu Shots.

MAILBAG:
Dave G6AJW builds Pete’s Sudden Transceiver
Rogier KJ6ETL builds a new shack
Steve N8NM Helps save the HT-37
Jim AL7RV W8NSA builds Parasets
Dave AA7EE puts a beacon on the air — Please Listen!
Jan OM2ATC builds and documents an Si5351 VFO
Bruce KC1FSZ Homebrew’s a BITX
KB1GMX’s Tip on IRF-510 Oscillation Prevention
Ryan W7RLF Homebrews a DC Receiver

 Listening to August K5HCT from the East and West Coasts on 40
Tim WA1HLR rebuilding his 1968 transmitter.


Old Station On-The-Air — A Transmitter Half as Old as Radio Itself

I’m biased, but I think it is “a thing of beauty.” With some unexpected free time available, today I followed up on my HT-37 work by cleaning and aligning the Drake 2B. I was assisted in this by one of the many great YouTube videos by Alan Wolke W2AEW.

The Drake 2B’s 50 kc and 405 kc oscillators were right were they were supposed to be — no adjustment required. And I don’t think they have been peaked since 1973. The 455 kc IF can was also very close to perfectly tuned.

Since most stations from the mid-1960s had some QSL cards on the wall behind the rig, I pulled out some old ones and put them up. Many of these contacts were made by the rigs in the picture.

If we say that 1897 marked the first use of radio, and if we assume that this HT-37 was manufactured in 1959, that means that my old transmitter has been in operation for almost HALF of the history of radio.

The AL7RV (W8NSA) Paraset, Regens, Test Gear, and Schematics Varnished into Enclosures

Jim W8NSA ex AL7RV is an old friend and a really talented radio builder. Over the years he has sent me many boxes of very FB radio parts. I’m sure that almost all of my homebrew rigs have parts from Jim somewhere in the circuitry. Jim recently sent in an update on his radio building efforts.

Bill,


 I managed to cobble up some regen’s over the summer. Most fun was my version of Dave Richards, AA7EE Sproutie, it turned out so nice I have it on my bedside table. Yes, the Sproutie has displaced the trusty old Transoceanic, brings back memories of late night SWL’ing with my Space Spanner as a teen.
The Sproutie worked well enough I’m considering a build of the Dave’s Sproutie MK II, maybe not in such a grand cabinet or with such fine metal work as Dave’s but a functional copy.

I also built the regen receiver from the SOE Paraset design, other then a coil winding mistake the receiver worked well at power up.

I built the Paraset receiver to test a number of mods others have suggested to improve the receiver’s performance. Using the mods involves modern solid-state components and additional band-spread functionally. Many consider the mods be in poor taste but they go well making a much better receiver.
I am ready to build my copy/version of the Paraset, now that I’ve missed SKN I have almost a year to get it built.
I’ve been gathering Paraset parts for years, was lucky to get in on the group purchase for a set of 3 Paraset knobs made from the same molds by the same company SOE used when building the transceivers in the 1940’s, having a real part of that history is exciting, to me at least.
Paraset Parts (see picture above) (some parts shown may not be in the proper location)

At last I have all the major components. I am at the point of gathering up the various resistors and small fixed capacitors needed. Some builders have gone to the efforts of embedding newer, smaller, parts in the carcass of vintage 1930s & 40s parts hollowed out and repainted. Too much effort for me, I want a functional radio, not a museum grade replica, but I really do want to keep the look of the SOE issued set.

Case and front panel…

Many of the U.S. Paraset builders are using a wooden craft box from Hobby Lobby, It is just about the correct size and shape. You can see at the right side of the photo a detailed panel layout. Building the Paraset is not quite Heath Kit but with so many talented builders having made so much information available I feel so lucky to follow the effort.

Years ago, during our RV travel days, I picked up a box of Bliley AX2 40 meter crystals. Good price and just about every one of the crystals were found to be working. Have a total of eighteen 40m crystals from 7.0024Mhz to 7.0986Mhz, have two 80m crystals in the CW portion but none of the AX2 crystals are for the traditional QRP frequencies, close but… AF4K and others are selling HC49 crystals for the QRP frequencies, problem is the 6L6/6V6’s used in the Paraset are known to be real crystal crackers.. (as was my 1964 novice rig!).

I’m considering the use of a transistor oscillator and driver stage to feed the 6L6 as a PA in effort to save the crystals and maybe allow the use of an outboard DDS VFO, yes I can hear the moans of dismay from other Paraset replica builders

The box included a number of sockets and crystal adapters too. Was great find. Having so may 40m crystals I’m starting to have thoughts of optimizing the Paraset build for just 40 meters. I can improve the sets performance but of course lose 80m and possibly 60m.

Today’s project while catching up on SolderSmoke Podcasts is a test device to aid in checking the resonant frequency of L/C networks. It’s always nice to prove your math is correct!
Building it Manhattan style into an old rat shack plastic box.


 I have always loved the way WW II equipment had the schematics varnished into the covers or cases. I try to do the same with most of the things I build.

Schematic reduced to fit, ink-jet printed. Using an old credit card I spread a very thin layer of E6000 clear adhesive on the case, apply the paper image, then using a clean credit card or the edge of piece of circuit board feather the schematic into the adhesive.

Let dry for about 10 mins, wipe off the excess glue around the edges. Let dry for 24 to 48 hours and cover with a few thin coats of Testors Clear Lacquer Overcoat.. several thin coats, follow the recommendations for re-coat time on the spay your using.

Please read the cautions for using E6000. Pete may not be able to purchase it in his state!
The Paraset antenna output connections use a porcelain crystal socket, the AX2 crystal purchase included a few dead or empty crystal cases, I modified two of them to use as adapters.


OH! and yes, I’ll be using outboard low pass filters with the Paraset!


Thanks again to you and Pete for the blog and smoke efforts!

 73, Jim W8NSA aka AL7RV

Please Listen for Dave AA7EE’s New “Boris Beacon”

https://aa7ee.wordpress.com/2019/01/03/putting-the-hifer-brs-boris-beacon-on-the-air-finally/

 From Dave’s blog:

The beacon sends the letters “BRS” at 10wpm, with a break of 3 or 4 seconds between the end of one transmission and the beginning of the next, with a mighty power to the dipole of about 1mW. The frequency is a nominal 13556.9KHz (13.5569MHz), which varies either way by a few tens of Hz, depending on the outside ambient temperature. I will be overjoyed if anyone, anywhere hears it! There is no battery, so it transmits during daylight hours only. It comes on about half an hour after local sunrise, and goes off about half an hour before local sunset. I’ll update this with more accurate information, as I observe the on and off times over the next few days.
—————
AA7EE is in Oakland California. His cat is named SPRAT. Please send him a report (and if possible a recording) if you hear his beacon.


New Rock Video By Astrophysicist and Queen lead-guitarist Dr. Brian May


We don’t carry many music videos on this blog, but this one definitely belongs here. We’ve mentioned Brian May several times: Lead guitarist in the rock group Queen. PhD Astrophysicist.

I didn’t know that he went to work as a full member of the New Horizons (Pluto and beyond) mission.

The video is definitely for us — it features a lot of antennas. And it includes the computer-generated voice of Stephen Hawkings.

Read more about Brian’s careers and about his latest adventure here:

https://www.space.com/42875-brian-may-new-horizons-song-ultima-thule-flyby.html

New Horizons principal investigator Alan Stern poses with astrophysicist and Queen lead guitarist Brian May on Dec. 31, 2018 at Johns Hopkins' Applied Physics Laboratory in Maryland just before New Horizons flew by Ultima Thule.
New Horizons principal investigator Alan Stern poses with astrophysicist and Queen lead guitarist Brian May on Dec. 31, 2018 at Johns Hopkins’ Applied Physics Laboratory in Maryland just before New Horizons flew by Ultima Thule.

Credit: NASA/Bill Ingalls

HNY (Happy New Year), SKN (Straight Key Night) 2019, and an HT-37 with “presence” — even on CW

I got the HT-37 working just a few days before the New Year’s Eve/New Year’s Day Straight Key Night event. Looking at my older blog posts, I now see that the problems first surfaced in LAST YEAR’s SKN. Wow, it took me a long time to get to that problem. But I’m glad I fixed it in time for SKN.

For SKN I used the VU3XVR straight key from India that Farhan gave to me. See the picture above.


I started out on 80 meters on New Year’s eve. I rarely operate on that band — I thought it would be a good change of pace. Here is who I contacted on 80 CW:

In the warm-up period before the official start of SKN I worked John KU4AF. John was running a homebrew tube transmitter and a REGEN receiver. Respect, my friends. RESPECT!

N9EP Ed near Chicago was on a K3.

VE9XX Don was on a KX3.

NJ8D Tom in Ohio.

K4IA, Buck, down the road in Fredricksburg Va. Buck was running a Drake TR4C with a Begali key. FB Buck. He mentioned that he had had a Drake 2B — he said he regrets selling it. Indeed.

VE9WW Bill in Moncton NB. On a straight key.

AA8MI Gene (gosh, that name really sings in CW — try it!) in Ohio. Gene was running 5 watts from a K3. This added a needed QRP element to the festivities. Thanks Gene.

AI4SV Jack in Rockville Md. OH MY GOD! NOW I REALIZE WHO THIS WAS! Jack! Jack of Antanarivo Madagsascar! And now I understand what he said to me. He said in CW that my HT-37 has “Lots of presence.” Huh? What? I couldn’t figure out what he was talking about, but now I realize that he was joking about all our discussions mocking the poor audiophiles. Well, thanks Jack. I’m glad the rig has presence, EVEN ON CW! THIS QSO GETS MY VOTE FOR BEST SKN QSO.

I also listened for a while to W3GMS. His signal had a lot of character and personality. He was telling the other fellow that he suspected this was the result of a soft voltage regulator tube in his DX-60. I think he was also using a Drake 2-B. I didn’t get a chance to talk to Howard, but I’m sure it would have been fun.

On New Year’s morning I switched bands. First to 40 where I worked Greg NM2L near Atlanta. He said he fingers and wrist were out of condition, but I told him his fist was FB.

Then I went to 20 CW where I worked a bit of DX. First David F8CRS then Bert F6HKA. The contact with Bert reminded me of the charms of DX contacts using CW. “VY GM DR OM.” It was nice.

N7AQQ Mike in Montana.

So it was a good SKN for me. Working the French stations reminded me of the allure of listening to CW coming in from far away, and from a foreign culture. And it was great to hear from AI4SV that my HT-37 has “presence” even on CW.

73 and HNY to all.

HT-37 Choke Failure — Why did this happen? What is your diagnosis?

Look, it has been 60 years, so I’m not looking for my money back or anything, but having just repaired the LV power supply choke on my very venerable Hallicrafters HT-37, I started thinking about how and why it failed.

Clues:

— I found it with four of the windings broken, with the eight broken leads kind of sticking out of the winding wrap.

— The four broken leads were on the outside of the winding (thank God!) an were at the part of the winding closest to the chassis and the back of the cabinet. (See picture below.)

— There was evidence of burning on at least two of the leads.

— The choke is located in the extreme back corner of the chassis, near the back of the cabinet.

— The paper and cellophane wrapping around the windings was a bit deteriorated.

So, what is your diagnosis? What happened to cause the choke to go open?

KC1FSZ’s Peppermint III Homebrew BITX with Mods


Hi Guys:

I had some time over the holiday to finish off my second scratch-built rig. I am very thankful that I got the work done on these projects before I read Pete’s “Don’t Build It” diatribe. That would have been very demoralizing. 🙂

Scratch build #2 (called Peppermint III) is still fundamentally BITX although I’ve made changes this time around. I’ve switched to ADE-1 mixers with LO ports driven by adjustable gain buffers (ala N6QW LBS). I’ve noticed that performance can be improved a lot if you can buffer/tweak the LO levels of the VFO and BFO (particularly carrier suppression on TX). I did W7ZOI TIAs in the IF chain. I’ve also taken the shielding/layout of the finals more seriously and have been able to dial up the power a lot (I did the KB1GMX thing with cutting off the drain pin on the IRF510 and using the tab). The software is also greatly improved and now supports LSB/USB modes as well as software-driven PTT control for RTTY/FT8 and the hooks for my poor man’s panadaptor. I’ve been working lots of stations on QRO.

Total build time was about three months (half the time of #1) and the layout came out much smaller than before. I made a trip over to Williams/Sonoma after Christmas and picked up the 2018 edition of the Peppermint Bark candy tin on discount and I think I can make it all fit. More to follow …

Happy New Year and 73s,


 Bruce KC1FSZ


HT-37 FIXED — Thanks for all the support

Don’t worry– I covered it with tape

This week I found myself with some unexpected free-time, courtesy of the government shutdown. And of course, my thoughts turned to the HT-37. I started thinking about the open choke in the power supply. Four wires were sticking out of one side, four sticking out of the other. Figuring out which went to which would have driven me nuts. But it occurred to me that I could just wrap the four one on both sides together, and then just connect them with a piece of wire (see above). I’d end up sacrificing three windings, but that shouldn’t matter.


It worked. My AADE L/C meter won’t measure up into the full Henry range, but the choke was no longer open and the resistance looked right (about 230 ohms).

I put it into the HT-37. It works. I had a long rag chew with AE2EE — a guy who really knows his boatanchors. He said it sounded great. This contact was like icing on the cake. TRGHS.

Thanks to everyone who wrote in with offers of parts or suggestions on how to acquire a suitable replacement.

Special thanks to Steve Murphy, N8NM who removed the LV choke from a junker HT-37and mailed it to me JUST AS I WAS LEARNING THAT THIS REPAIR WOULD WORK. I feel bad about putting Steve to the trouble. I blame the shut-down. Idle hands are the devil’s workshop. And that broken HT-37 was bothering me.

This was a very satisfying repair. It was great fun to put the old rig back on the air. And I did it without injuring myself. Straight Key Night is right around the corner.

Terminal strip for newer caps. Repaired choke went to the two ends of the strip.


W7RLF Homebrews a Receiver — FB!



Ryan W7RLF has joined the small and elite group of radio amateurs who have homebrewed a receiver. And it is a receiver filled with soul, juju and mojo; the project was inspired by Wes Hayward and Farhan, and used components from Hans Summers. Congratulations Ryan and thanks for all the work you did in documenting your experience.

Who will be the next intrepid ham to join the homebrew receiver club?

Hello Sirs!


This month I read Wes Hayward’s post on the history and heritage of DC receivers in ham radio and it brought a lingering interest to a head. I had to build one. I run the BITX40 and uBITX group on Facebook, and I posted to the other hams there: Which DC receiver should I build? Farhan recommended his DC40. Mind you, I’ve never homebrewed a radio before, so this is all new territory for me.

I did build it, and it does work. It also uses QRP Labs stuff from our friend Hans Summers. This thing has a lot of QRP heritage 🙂 I documented it every step of the way including all of my dumb moves and things I got wrong, and my desire is to inspire others to try homebrewing the way Wes, Farhan, Hans, and you YOU GUYS have inspired me to try it. I am hooked, of course! Here’s a link to my blog to Part 1:


It’s a four part series (unofficially 5 really) with 8000 words to it, and I hope you guys enjoy it and I’d be ticked pink if was worthy of mention on your show. Here’s a video of it too:


73 to you both and I wish you the best!

Ryan Flowers W7RLF

Ghost Ship: Oscar 11 Tumbles Through Space

First — Happy Boxing Day to all our UK and Commonwealth friends.

Oscar 11 is a UK-built amateur satellite launched in 1984. It has been dead (well, almost dead) for many years. But when the sun shines on the solar panels, it wakes up and transmits. I’ve been able to hear it and — more usefully — see it on my RTL-SDR HD-SDR receive system. My antenna is my re-born (from the Dominican Republic) three element homebrew 2 meter cubical quad (see pictures below).

I’m sorry the video is a bit out of focus, but you can clearly see the trace of the signal from the satellite. Realize that my HD-SDR software is about 10 kHz off calibration. You can see the Doppler shift, and you can see the signal fading in and out as the old satellite tumbles through space. Any ideas on what the other signals seen off to the side are? Is anyone else listening for Oscar 11?

https://amsat-uk.org/satellites/telemetry/uosat-2-oscar-11/

https://en.wikipedia.org/wiki/UoSAT-2

http://www.dk3wn.info/p/?cat=47
UOSAT_OSCAR-11

All I want for Christmas is… an HT-37 L25 Choke– 9 Henries at 135 ma


 Following my own advice to prepare for Straight Key Night, I tried to fire up my venerable Hallicrafters HT-37 transmitter. It didn’t work. I quickly determined that none of the oscillators were working, so my troubleshooting focused on the power supply. Sure enough, the choke in the low voltage power supply is open. That’s bad.

I briefly considered giving up on this old rig. I don’t really like working with tubes anymore. And this thing is very heavy — a real beast. DX-100-like in its heaviness. It can be hazardous to your health just moving this thing around. Opening up the case is not easy. And there are nasty voltages in there….

But I have had this transmitter since 1973 or 1974. I have fixed it many times, in several countries. I got it from a member of the Crystal Radio Club when I was a kid. There are parts given to me by Pericles, HI8P in the Dominican Republic. I used it to transmit through Russian satellites. That transmitter is like an old friend. I just can’t give up on it.

So I need to replace or repair the choke. Is there anyone out there who has a junker out in the garage or some other source of L25? Or does anyone know of a business that could rewind the choke. Please let me know. I have decided to leave the rig on the bench until I get this thing fixed (it is too heavy to move multiple times!)

It it Hallicrafters Part Number 056-300259. L25 — 9 Henries at 135 ma. Help!

SolderSmoke Podcast #208

SolderSmoke Podcast #208 is available:

http://soldersmoke.com/soldersmoke208.mp3

 15 December 2018

 Pete and the California fires
Bill goes to Brooklyn
2 meter simplex
A return of the trivial electric motor
Audio from Mars
HF Conditions — a real mixed bag

 Pete looks back at 2018 — The Year of the SSB Transceiver — Lessons Learned

 Hans Summers, the QSX and the virtues of SDR
W7ZOI’s DC Receiver Retrospective
The 1972 Solar Flare and the Vietnam War

 SHAMELESS COMMERCE: Buy your gifts through the Amazon link to the upper right.
Consider SolderSmoke the book as a gift. Visit Pasta Pete’s for cooking ideas.

Don’t Build It! Sage — but unexpected — advice from Pete.

Straight Key Night approaches.

Book Reviews:
–“What is Real?” (Quantum Physics)
— RHdb by K6LHA.

 Movies
“Bohemian Rhapsody”
“First Man” (Not yet!)

 MAILBAG:
Steve G0FUW
Ed KC8SBV