Free Book! "SolderSmoke -- Global Adventures in Wireless Electronics" by Bill Meara. Free for the Next Five Days

 

From time to time, Amazon lets me make my books available for free on Amazon Kindle.   SolderSmoke -- Global Adventures in Wireless Electronics is now -- and for the next five days -- available for free download.   Use this link: 

https://www.amazon.com/gp/product/B004V9FIVW/ref=dbs_a_def_rwt_hsch_vapi_tkin_p1_i1

Please spread the word and post reviews.  Comments posted on the Amazon page (above) are especially welcome. 

Where Do You Think This Variable Capacitor Came From? What Piece of Gear Did it Come out of? Is it in the Old Catalogs?

 

In an effort to stop the slaughter of innocent Heath QF-1s (for their very nice variable capacitors), I bought this thing on e-bay.  Here is the info I have: 

https://www.ebay.com/itm/255622418189

I checked the resonance of the cap and the coil:   It tunes from about 10.140 MHz to about 13 MHz.   The cap is nice -- brass vanes and with the linear tuning shape.  I don't know about it being from a Hartley oscillator -- no signs of a tickler coil.  There seems to be some sort of a pass-through cap from "Faradon" of Camden N.J.  

Update: 

It tunes from about 9 to 138 pf. The coil that it had on the back of the cap is about 1.6 uH and is tapped (Hartley style). The capacitor is marked on the back: "Licensed Under Pats. MC 15257781258423"

From the e-bay ad: 

"Here's a great project part.  These were likely a VFO assembly for some RF equipment from the late 1920's or 30's.  Essentially it's 4" Type A Velvet Vernier dial (standard 5:1 reduction drive) with a variable capacitor.  The variable condenser is a high quality ceramic frame with brass plates and looks suspiciously like a General Radio house part (also in Cambridge at that time). The variable condenser looks like a SLF shape or similar, about 135pF.  It has a ceramic frame and has an insulated shaft, which was critical to keeping hand capacity down back then.  It appears to be wired for a Hartley oscillator, probably 10 MHz+ give or take (not measured).

The vernier is in excellent condition--smooth, without backlash or sticking.  There are no chips in the skirt and the numbers and nice and clear--these were obviously well cared for over the years.  They have the the hard-to-find dial markers!

There is a rigid metal panel to which the vernier assembly is attached, and this in turn supports the condenser frame.  I suppose you could just that in a project box with an appropriate sized hole for the shaft and have an instant shielded enclosure for a VFO, or maybe screw it to the side of a breadboard.  You can also remove the vernier assembly from the panel and use it separately (e.g., to fix up an old NBD).  Lots of possibilities.  

There is a loose sheet-metal collar behind the rigid panel that friction-fit a (now missing) can that went over the whole assembly. It's easy enough to unscrew the front and remove this piece.  Everything comes apart if you want, including the unobtainium dial pointer."

So where do you guys think this very nice cap came from?  Who made it?  Was it salvaged from a piece of radio gear?   Does it appear in any of the old catalogs?  

New Video: Farhan's Presentation on the "Daylight Again" Analog Transceiver

LOTS of tribal wisdom in this presentation by Farhan VU2ESE. 

For more info, go to: 

https://www.vu2ese.com/index.php/2022/08/04/daylight-an-all-analog-radio/

Old Smoke: SolderSmoke's Early Theme Music from W8MOJ, Boatanchors in South Africa, and Homebrewing in Dubai

Over on the SoulderSmoke YouTube channel I have been putting up some podcasts from days-gone-by.  Recently they have been from our last days in London and our earliest days in Rome.  We have had a nice series that includes "Echo-calls" from Andy ZS6ADY  in South Africa, talking about old tube radios (Boatanchors) in that country.   Soon we will start a series that includes Echo-calls with Ron Sparks AG5RS, who was homebrewing in Dubai. 

But these early podcasts begin and end with some very distinctive techno-music from Mark O Johnson, W8MOJ.   Here is our old blog post that describes Mark's musical contribution to SolderSmoke.  Thanks Mark!  https://soldersmoke.blogspot.com/2011/01/tech-details-on-soldersmokes-theme.html

Building a Solid-State "Magic Eye" and Fitting it in the Old Tube's Glass Envelope

I was feeling kind of bad about my solid-state conversion thoughts.  I had gone so far as thinking about putting an FET and some resistors in an old tube's glass envelope.  There was something about this that felt well, kind of immoral. 

But then this morning Facebook sent me the video above.  This fellow built the solid state equivalent of an old Magic Eye thermatron!  And he put it inside the glass envelope of the old tube.  FANTASTIC!  

I feel better already. There are others with similar thoughts, and some who have put these thoughts into action!  Maybe now the Thermatron Protection Society will call off the protests outside my house, and I can stop wearing the Kevlar vest. I know, haters gonna hate, but after seeing this video I realize that I am FAR from being the most egregious of thermatron defilers. 

Free Book by Bill Meara -- Not About Radio. But it is about family life on a very long trip.

Free! From time-to-time Amazon Kindle allows me to make this book available FOR FREE. You can get the Kindle version for free until the end of August. Here is the link: https://www.amazon.com/dp/B00L8DR4RK

All I ask is that you spread the word, and post reviews. I hope you like it. Thanks, Bill  

https://www.amazon.com/dp/B00L8DR4RK

SDR on a Breadboard -- But Isn't This an Old-Fashioned Fantasy?

Nice video, but I'm afraid it is a bit of an old-fashioned fantasy.  It would be nice to think that our beloved analog mixers and direct conversion receivers still have a place in the SDR world.   That may have been true a few years ago when we were using soundcard-based SDRs.  But today we just put an Analog to Digital Converter at the antenna, do "Direct Sampling," create a digital stream, and sent it to the CPU for processing, right?   

Sometimes we think that we can show younger people how our older tech (Direct Conversion receivers) is STILL relevant in the age of SDR radio.  But I can just hear them scoffing at this notion, pointing out that I,Q-to-soundcard front ends have gone the way of the dinosaurs, and all we need now is an ADC and a CPU.  

But hey, I am an HDR guy.  Am I missing something here?  

PA3CRX's 6 Meter BITX in an Old CB Case

Thanks to Rogier PA1ZZ for alerting me to this video and to the PA3CRX YouTube channel. 

I like what Chrix did with the old CB transceiver case -- this gives me ideas about the old transceiver that I picked up at a hamfest a while back.  I also like Chrix's practice of running coax and power leads UNDER the main BITX boards.  

Chrix has been building some great stuff and making some very nice videos -- I have put his channel on the SolderSmoke links in the right-side column of this page. 

SolderSmoke Podcast #73 Jan 2, 2008 -- AA1TJ Circuits and Poetry, Mixers, CW, Straight Key Night at WA6ARA, Boatanchors in South Africa with ZS6ADY (Part 1)

This is the first in a series of four podcast that include Echolink conversations with Andy ZS6ADY about old tube radios (boatanchors) in South Africa.  Click on the YouTube link above to listen. 

January 2, 2008 SPECIAL NEW YEAR'S EDITION AA1TJ's circuitry and poetry. Homemade tubes. Book Review "Early Radio" by Peter Jensen. The Vatican's antennas. Google Earth flight simulator. Mixer madness continues (now in LTSpice). Mars-asteroid collision? Bollywood: The BITX-20 connection. BANDSWEEP: Straight Key Night at WA6ARA. ECHO-GUEST: Andy, ZS6ADY, South African Boatanchor fan. MAILBAG: Jake N4UY(NOVA QRP), Steve G0FUE (Bath Build-a-thon), Nigel M0NDE

Solid-Stating an HT-37 VFO -- Advice Needed

 

Original HT-37 VFO Circuit

A couple of things before I start:  

First, this is not my fault.  The Radio Gods are to blame.  I innocently tried to by an HT-37 tuning capacitor on e-bay, but the seller sent me the entire VFO unit.  The only thing missing was THE TUBE. Clearly, that was a sign, right?  

Second, this is a work in progress.  That is why my diagram (below) is a bit ugly.  I am looking for your input and advice on how I might do this better.  I will understand if religious principles prevent some of you from participating in this endeavor. 

I am trying to solid-state this device WITHOUT major surgery, and without adding any reactive components that would change the resonance or tuning range of the original.  The original circuit tunes from 5 to 5.5 MHz and that is fine with me.  

I started out by just sticking a J-310 FET into pins 1, 2, and 5 of the tube socket.  I put 12 V on the drain and the thing oscillated right where it is supposed to.  That was a good sign.  

Here is what I have done so far: 

Bill's initial solid state conversion of HT-37 VFO

Mechanically, my effort has been very simple.  At first I tried to fashion a more serious male socket for the FET using two broken 7 pin tubes.  This didn't work well.   

So then I just ran three short wires up through the center hold of the tube socket to the connections for pins 1,2, and 5.   I superglued the J-301 to the chassis and made some non-reactive connections: I put a 47 ohm resistor on the source,  and a 220 ohm resistor on the drain. I grounded the drain for RF with a .01 uF cap to ground.    I added a 100k resistor and a diode on the gate.   Oh yea, I put a couple of ferrite bead on the FET gate lead.  (See pictures below.)

Three lead up through the center hole

A rare look inside an HT-37 VFO

The original thermatron circuit has an output bandpass transformer, a 3900 ohm resistor and a coupling cap.  I left them in the circuit, but they are not doing anything. 

The output from the source of the FET looks pretty good.  I can see some VHF on the trace, but I suspect this is from my FM broadcast nemesis at 100.3 FM (one mile away).  On a receiver, I can hear some AF noise on the signal, but this may be the result of the RFI from THE BIG 100 -- WASHINGTON'S CLASSIC ROCK. 

So what do you folks think?  What else could I do, or should I do?  

SolderSmoke Podcast #156 -- November 4, 2013 -- Interview with Peter Parker VK3YE of Melbourne, Australia

November 4, 2013
Special hour-long interview with Peter Parker, VK3YE
-- Early experiences with radio
-- CW
-- DSB Gear
-- Simple gear, and gear that is TOO simple
-- VXOs, Super VXOs and Ceramic Resonators
-- Building receivers
-- Chips vs. Discrete
-- Making the leap to SSB
-- The Knob-less wonder and the BITX
-- No need for a sophisticated workshop
-- Advice for new phone QRPers

Peter's Blog: https://vk3ye.com/

Peter's YouTube Channel:  https://www.youtube.com/user/vk3ye/featured

Mike Caughran KL7R's Last Podcast

 

Mike KL7R (SK) during a visit to the AL7FS shack.

This was Mike Caughran KL7R's last podcast. He died in a car accident shortly after we made this program. January 13, 2007. Mike's oscillator work. Michigan Mighty Mite. Lasers, diodes, and Einstein. Laser communication experiment. W7ZOI-KL7R QSO on SKN.M0HBR's feedback amps.The new comet. Saturn, Jupiter and calculation of c. 17 meter QSOs. New SPRAT CD. MAILBAG: China enigma, VE4KEH, M0DAD, GU0SUP, M1CNK, K4AHU, KD4EDM, KG9DK, AA6KI, VA7AT ON5EX

---------------------

Mike's Obituary from the February 2007 ARRL Letter:

Mike Caughran, KL7R, SK: Well-known low-power (QRP) and homebrewing
enthusiast Michael S. "Mike" Caughran, KL7R, of Juneau, Alaska, died January
22 of injuries suffered in an automobile accident in Hawaii. He was 51.
Caughran may be best known as one-half of the team -- with Bill Meara,
N2CQR/M0HBR -- that created and produced the weekly SolderSmoke podcast
<http://www.soldersmoke.com/>. "I think people were drawn in by Mike's
friendly voice and manner," Meara commented on a memorial page for KL7R
<https://kiwi.state.ak.us/display/mc/Home>. A member of ARRL and the Juneau
Amateur Radio Club, Caughran also wrote articles for the Michigan QRP Club's
T5W newsletter and he was an active ham radio contester. "Mike was one of
those people who you instantly like because of his honest, straightforward
and humble way of talking and expressing ideas," said Mike Hall, WB8ICN, who
edits T5W. "His co-hosting of SolderSmoke provided me hours and hours of
enjoyment." Caughran was an IT professional with the State of Alaska.
Survivors include his wife and son.