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Topic: Old hams were a hardy bunch |
Ray Minich
From:
Bradford, Pa. Frozen Tundra
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Posted 24 Jul 2009 7:36 am |
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This is a schematic from the 1949 issue of The Radio Amateurs Handbook published by the ARRL.
Notice the headphone circuit. Hopefully the insulation on the phones was REAL good.
Audio output transformers must have been yet to be invented.
Hams must have been a hardy bunch to withstand the occasional jolt to the head...
Joey, feel free to put this in the Humor section if you feel so inclined  |
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Dave Mudgett
From:
Central Pennsylvania and Gallatin, Tennessee
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Posted 24 Jul 2009 8:57 am
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That is really quite bizarre.  |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 24 Jul 2009 11:43 am
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Quite normal for that time. Transformerless (AC/DC) AM radio sets were all the rage in the '50s and early '60s. Plug the set in the wrong way...and the chassis was at line potential! Funny thing was, the plugs weren't polarized - supposedly so that if you plugged it in the wrong way (and got a shock), you could easily reverse the plug and be safe even if your outlets were wired wrong! 
Young people don't understand...things were different back then. People would rage if the gasoline went over 30 cents a gallon, and you could buy dynamite, jugs of acid, or a pistol at just about any hardware store - once you got out of the city limits. |
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Jack Stoner
From:
Kansas City, MO
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Posted 24 Jul 2009 1:38 pm
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The Headphones used back then were a different type than what is used now. They could take the high "B+" voltages. No one worried about the potential to get shocked.
I was a morse code radio operator in the Air Force and we used that type of headset as standard issue.
I am also an ex General Class Ham Radio Op (W5DVO/K3FFZ/ZD8JES) and had a 2nd class FCC Radiotelephone license. |
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john lemay
From:
Ainsworth NE
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Posted 24 Jul 2009 4:07 pm
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6SN7's were one of my favorite tubes. You could build most anything with them. I built my first modulated transmitter with a pair of them. I'm showing my age I guess..
John, AC3G |
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Dave Mudgett
From:
Central Pennsylvania and Gallatin, Tennessee
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Posted 24 Jul 2009 7:19 pm
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Um, I think audio output transformers were most definitely around by 1949. This looks purely like an economy move to me - I presume this is instructions from a hobbyist kit. Thanks, I think I'd use a transformer. I'm not that young and have worked around a lot of electronic equipment, but that just seems to be asking for problems.
On the unpolarized 2-prong wiring - I do understand. My old blackface and earlier Fender amps came with unpolarized AC plugs and ground switches. But I still think it's a good move to set them up with 3-way wiring and plugs with a proper ground to give a safety valve in case a serious ground fault happens. With the B+ voltages in some tube amps going as high as 500 VDC or even 700 VDC (in some Music Man or Ampeg amps, for example), I sure don't want to be the least-resistance path to ground if something goes wrong. |
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Blake Hawkins
From:
Florida
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Posted 24 Jul 2009 8:07 pm
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The headphones were not a problem as regards to getting an electric shock.
I started with a one tube radio in 1946, using plans that were made in the '20's. In the time between
then, I've built many similar radios, all using that
circuit for the headphones and never had or worried about a shock.
As Jack mentioned, the headphones were a different design and impedence. Most double sets were 2000, or 4000 ohms.
One tube radios provided many hours of enjoyment
for thousands of hams and radio hobbiests as well as contributing to their construction skills and radio knowledge.
The "AC/DC" sets mentioned by Donny were mostly used
in home radios. (The Hallicrafters S-38 series
and National SW-54 plus a few Echophone radios also
used them.)(OK, also the Hallicrafters S-77 and there could have been a few others.) 
However, all quality communications receivers used
power transformers starting in the late '20's.
The "AC/DC" transformerless radios started appearing
in the early '30's as a effort to make cheaper and cheaper radios for the mass market during the "Great
Depression."
DC power was still used in the North East into the 1940,s in some hotels and office buildings who
still had operating Edison Generating equipment.
Blake, N4YCQ |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 25 Jul 2009 3:53 am
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Right Blake. The "low buck" AC/DC radios were usually easy to detect, even without removing the back. (Most had a tube chart on the bottom or the back, and the filament voltage of the tubes was usually the first numbers in the tube number. (A 6SN7 had a 6 volt filament, and a 35W4 had a 35 volt filament, and so forth.) Since most of the AC/DC radios had only 4 or 5 tubes (and no tranformer), those filaments had to be hooked in series, and therefore the filament voltages all added up to around 110 (volts). Tube numbers like 50C5 and 35W4 were a sure sign of a transformerless design.
Incidentally, the output transformer goes back to the dawn of radio, in the '20s. Tubes, being characteristically high-impedance devices, needed a transformer to match them to their speakers (which were low impedance devices). |
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Mark MacKenzie
From:
Franklin, Tennessee, USA
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Posted 25 Jul 2009 5:13 am
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Great stuff. The five tube radio was called an "American Five" I think or even a "Fiver." I listened for hours to my National SW-54 as a kid.
I wonder how the tone of a 6SN7 or a 6SL7 as a pre-amp tube compares to a 12AX7. Anybody have experience with them?
That receiver could be considered dangerous but.... those old handbooks have more useful information about electronics than anything else I have. I have a 1956 handbook that is full of applicable theory and practical info. Tube theory, resistor and component characteristics, power supplies, on and on. The modern handbooks are lacking in the tube stuff but totally up to date on new technologies. More receiver, transmitter stuff than audio but great reference to have around a shop! |
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David Mason
From:
Cambridge, MD, USA
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Posted 25 Jul 2009 5:31 am
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| Quote: |
| But I still think it's a good move to set them up with 3-way wiring and plugs with a proper ground to give a safety valve.... |
- Sissy. Back when men were men and amps were amps, we used to wire 'em up backwards on purpose just to keep the grizzly bears from stealin' em.  |
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Blake Hawkins
From:
Florida
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Posted 25 Jul 2009 6:20 am
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Right on Donny!, You've got the "All American Five"
well defined.
The dynamic speaker was, I think, invented by Magnavox sometime in the late '20's or early
30's. (Would have to do some research to pin down the exact date.)
However, the earliest "loudspeakers" were nothing more than a headphone driver with an acoustic horn
in front of it to concentrate the sound. I'm sure
everyone has seen pictures of those.
The next thing was the "Magnetic" speaker`which
was a paper cone driven by a metal vane in
a coil with a big horseshoe magnet. These were
high impedence and usually directly driven as in
the headphone example.
The "Magnetic" technology actually existed in parallel with the dynamic speakers for many years.
I had a 1935 "Kaydette" small table radio which
had a magnetic speaker. Again, this was a cost
thing since the output transformer was not required
and thus a cost saving there. It used all the features that Donny mentioned as well.
The tone quality of the magnetic speaker was pretty bad and it could only handle very low power.
As far as I know, they were never used in guitar amplifiers.
The electro-dynamic speakers could handle plenty of power and I believe were used in even the earliest
of guitar amps.
Blake |
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Blake Hawkins
From:
Florida
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Posted 25 Jul 2009 6:30 am
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To get back to Ray's original diagram for the one tube radio.
The "B" supply needed is shown as 180 v DC.
I gather that this was the initial "shock factor" together with the open terminals.
I happen to have the original article as well. It also includes a power supply which is transformer
operated and, thus safer than the "AC/DC" power supplies we discussed.
As for the open terminals, well us "older" hams
learned to keep our fingers off of those things.
73's
Blake, N4YCQ |
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Gerry Simon
From:
Ohio, USA
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Posted 25 Jul 2009 3:30 pm
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Blake, I wonder if there has ever been a thread to see how many steelers are hams???
Gerry...K8JEA |
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Blake Hawkins
From:
Florida
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Gerry Simon
From:
Ohio, USA
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Posted 25 Jul 2009 9:13 pm
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| HOLY CRAP!! That's downright weird! Seems way out of proportion! Thanks...Gerry |
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Joey Ace
From:
Hamilton, Ontario, Canada
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Posted 26 Jul 2009 5:16 pm
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| Quote: |
| Joey, feel free to put this in the Humor section if you feel so inclined |
I like it here.
Not many would understand it there.
Besides, I'm not sure it's funny. It is an interesting historical oddity.
Seems dangerous today, much like driving without seatbelts or airbags, which was also the norm back then. |
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Ray Minich
From:
Bradford, Pa. Frozen Tundra
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Posted 27 Jul 2009 6:46 pm
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OK, I'm back, just got the DSL up & running.
I spent many an hour as a kid tring to build this darn radio described herein. Used homemade coilforms and tube sockets to make the tuning coils, intead of the nice coilforms those ARRL dudes enjoyed. Coilforms made from spent toilet paper tubes.
I also built a crystal radio, (germanium diode, I got to forego the catwhisker/galena misery) then built a 3-tube audio amp (35W4, 12SQ7, 50L6) to drive a speaker, fed from the crystal radio
My real "AHA!" was my own change in perception, caused mostly by the past 40 years digital and analog work.
Just purchased a hardcover of the 2009 edition of the handbook. Neat stuff. They've been printing them since 1939.
(John Lemay: 6SN7's don't have the mu or voltage gain that you can get from a 12AX7. They can take a beating though. They're more like a 12AU7. Lower gain, rugged, bounce back from screw-ups.)
Thanks for the great comments. |
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Erv Niehaus
From:
Litchfield, MN, USA
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Posted 28 Jul 2009 7:34 am
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I don't know squat about what you guys are talking about, however, I did put a crystal radio together at one time.
I don't know what kind of headphones I was using but if I had an acoustic guitar without a pickup, I would just clamp the headphones around the body and plug the jack into an amp. Made for a pretty decent pickup. |
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Lee Baucum
From:
McAllen, Texas (Extreme South) The Final Frontier
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Posted 28 Jul 2009 8:25 am
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It has been my experience that old hams usually turn green. Then, they need to be thrown out.  |
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Phil Turcotte
From:
Ontario, Canada
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Posted 9 Aug 2009 7:41 am
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Speaking of old ARRL Handbooks, I have a quite a pile of them that I'd like to find homes for. Resale value of these things seems to be practically nil; I hate to throw them into the recycle, so I'd be happy find foster homes for them.
Any interest ? Should I post a list ?
Phil |
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John Billings
From:
Ohio, USA
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Posted 9 Aug 2009 10:34 am
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Mark Mac
"I wonder how the tone of a 6SN7 or a 6SL7 as a pre-amp tube compares to a 12AX7. "
I have a Fender Pro Amp, 1952, model 5C5 (I think). It uses three 6SC7s. When the tech, my best bud, serviced the amp, he built me a set of octal to mini converters. We tried them with 12AX7s, and AY7s, and put the octals back in. The amp just sounded better with them. |
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Mark MacKenzie
From:
Franklin, Tennessee, USA
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Posted 9 Aug 2009 4:58 pm
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Thanks, John, I have heard that the octals sounded different. I think I would like to build something with a 6sl7 pre amp.....
Hey Phil, I would be interested in those handbooks. However you want to handle it....Post a list if anyone else is interested. They have a great deal of tube radio information!
Mark
KC4KFC |
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Ray Minich
From:
Bradford, Pa. Frozen Tundra
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Posted 13 Aug 2009 5:12 am
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Phil:
I'll take 'em and make sure the legacy gets handed down to future generations. Send me a private email.
Thanks |
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Bob Lawrence
From:
Beaver Bank, Nova Scotia, Canada
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Posted 19 Aug 2009 6:55 pm
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re:caused mostly by the past 40 years digital and analog work.
What's all this digital stuff you guys keep referring to? I'd like to learn about it. It must be something new but I don't see anything about digital in my handbook (1964, the 50th year for ARRL) and it's newer than the one that Ray has. 
The price tag on it is $3.50 U.S.A. Proper |
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Phil Turcotte
From:
Ontario, Canada
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Posted 19 Aug 2009 9:07 pm
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Mark...Ray,
Thanks for the interest. I'm in Edmonton (Alberta) this week but I'll be back home in Ontario this weekend. I'll put together a list of the ARRL handbooks I have when I get back.
Ray : you hit the nail on the head. I guess I am interested in seeing the legacy passed on. That's actually how I came to own these old handbooks in the first place 20 years ago. |
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