Monday, June 1, 2015


     I went through most of my collection of carbon mics tonight.  The old ones are nearly always non-working when found: they pick up humidity, the carbon packs solid, and that's it; or the carbon granules dribble out over time. 

     Not all of them.  I found several that still work, and a couple that I'd thought were dead (a Shure Brothers 3-A and a 3-B) aren't.  Here are the working ones:
      Two are telephone-types, the T-32 (a pretty common desk mic around WW II) and an odd old telco one from the wood-wall and candlestick era next to it.  The Universal X1 in its nice stand was a complete surprise; I assumed from condition it was a goner.  Nope!  And the little Philmore lapel mic next to it had been sealed up.  The Stancor 10-P -- which needs a carbon mic to do AM -- is behind them.

     Here's my test set-up.  The mic cable goes to a little mixer.  It's isolated with 0.68 uF series condensers, looking at current across a 150 Ohm resistor in series with the mic, a 1.5 V battery and an added resistor to limit current -- I used 820 Ohms and it worked okay for checking.  In practice, you trim microphone current for best fidelity with a carbon -- usually the lower, the better, but there's a point where it stops working.
     Mic cable to mixer at left, connections to carbon mic under test at top right, battery terminals and added current-limiting resistor at bottom right.  I think you can trace it from the photo.

Thursday, March 26, 2015


     A very long time in coming, I did make progress on the Stancor 10P, getting as far as power supply:

     Rectifier heaters and HV, filter caps, filter choke and bleeder.  It's a little crowded and I struggled to solder the capacitor and resistor to the chassis, even with the big iron.

     That work had it almost done, so tonight I added a few more things:
     Installed output feedthroughs and connected the output, wired up the primary power and the meter.

     Top view:

     Rear view:

     Front view:
     Initial tests -- just power-up, check for excessive current draw, check B+ -- went okay.  Hoping to try more by the weekend.

     Update: Tuned the transmitter up on 40m with a 100 Watt lamp in series, and it made a little power (4:1 balun to a Bird Wattmeter and 50 Ohm load.  Tried it without the lamp and blew the fuse instantly.  So....bigger fuse, and/or 150 and 200W lamps.  Maybe a little Amprobing..

     Update 25 May: Yesterday, I finally brought the transmitter up without a light bulb in series with the 120V AC and it worked. Last time I tried this with the wrong fuse (fast-blow) and it popped immediately -- at which point, I set the transmitter aside for awhile. I didn't have the balun and wattmeter for this test, just a 40W light bulb across the output, which is a bit low-resistance for the link coupling to match to. Plenty more to do but this was a big step.

Thursday, January 29, 2015


     Some time ago, I chanced on a nice Yankee No. 100 tool set.  Readers suggested I keep watch for a No. 106 boxed set of "radio tools," which, other than a soldering iron or copper, contains about everything you'd need to build a 1920s-type radio -- and is plenty useful on later equipment.
     I have seen a few come and go at princely prices, including a lovely store display version.  They are fine tools but not on my budget.  Or not until some months ago, when a slightly-grubby one showed up on a well-known auction site.  The serious collectors weren't after it but many of the tools were there; it was hard to figure out what was going on with the little drill, which appeared to have been taken apart.  The wooden case is the most difficult part to find -- the No. 105 kit offered all the tools except the drill, at half the price and in a cardboard box -- and the case was certainly there.
     It arrived in disappointingly worse shape than the original listing showed, due to a poor packing job.  Adjustments, as they say, were made.
     The mystery of the disassembled drill was simple enough: it was the wrong drill.  This proved no hardship; the little Yankee "Radio Drill," No. 1431, is commonly found and inexpensive.

     At present, I am repairing the case, starting with the badly cracked bit holder.  The two long screwdriver blades are missing, as is the uncommon Ratchet Tool Holder No. 230.  They may be a very long while in the finding.
     The incorrect drill is nevertheless a treat: a No. 1530 Ratchet Drill, which can be set to operate in five different modes: plain, left-handed ratchet, right handed ratchet, right-hand double, or locked.  The last is handy when tightening or loosening the chuck, the simple ratchet modes only respond to one direction of turning the crank -- but "double" turns the chuck clockwise no matter which way the crank is turned! 

Thursday, May 29, 2014


     It is modeled after one published by Bud in the 1930s:
     I'm not too unhappy with how it came out.

Wednesday, May 28, 2014


     Any more, hams are not required to keep logs - but it is nice to have a record of who you heard from, and when.  Here are a couple for portable and mobile operation -- Field Day is coming up!
      The upper one is an ARRL original, found at a well-known online auction site.  The lower is one I made when I took a ham station along on an extended out-of-town trip.
     ARRL version is "shirt pocket" size, 6¼" by 4".  Mine is 8½" by 5½", trimmed from standard-size pages with one cut.

Saturday, May 17, 2014


     A selection of old keys -- and one new one -- from the Dayton Hamvention:
"Pendograph," with a base-supported vertical pendulum for forming dits.

Pendograph close-up.  The owner let me try it -- very nice feel.  It's a "release of tension" design like the Mecograph: the reed is flexed at rest, and released to vibrate when you work the left paddle.

"Automorse," an Australian-made fully-automatic mechanical key.  Full-auto for International Morse, as used on radio, anyway:  the third paddle is for the long dahs of landline Morse, and that's manual.

This is a Mecograph, one of two versions.

The original machine for live coverage of news -- cut into the nearest telegraph wire and get to sending! You see these in old photos of press coverage of sporting events and Presidential appearances.


A full-auto, all-mechanical key built by Indy's own brilliant Richard Meiss. He knows more about the physics of bug keys than any man alive. This key is palm-sized, and uses a mechanically-varied mass to switch between dits and dahs.

Sunday, February 16, 2014


     No copyright -- and no wonder; if you want to use these fonts, you're going to need a set of Speedball pens! 
      Full-size, this is a large image, intended for your use when lettering by hand.  The 16th Edition "Speedball Text Book - Lettering - Poster Design - For Pen Or Brush" that accompanied it, you'll have to find for yourself. It's a delight from another century, a succinct guide that presumes the reader has a modicum of talent or the patience to get the job done the hard way.  They're on to the 23rd ed. now; it would be interesting to see how much has been kept.