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I know that this board is mainly
about transmitting on Part 15,
but I forgot to mention an
experiment I did when the
hurricane blew through.I love crystal radios and have
I know that this board is mainly
about transmitting on Part 15,
but I forgot to mention an
experiment I did when the
hurricane blew through.I love crystal radios and have
mentioned them in the past. For
those of you who aren’t familiar
with the term, “crystal radio”
is a generic term for a radio
that gets all of it’s energy to
operate from the radio waves in
the air. It needs no other power
source, and usually because the
amount of energy is so small, you
have to use headphones to listen.
Most crystal radios are made just
for the AN broadcast band. There
have been crystal radios for other
frequencies, but that’s out of the
scope of my little message here.I have two fairly good crystal radios
here. One is the famous Heathkit CR-1,
that my dad gave me in 1962. It still
works fine. I also have a clone of the
CR-1 that is called the “Litz Traveler”
It’s pretty much the same radio. These
are not the best crystal radios around,
but they are good and are small and completely
self contained.Anyway, I wanted to get these radios working.
I got them out of storage and brought them
up to the com center I had assembled in
Dog Radio Studio 2. These were ham radio
gear and scanners, which I actually never
had to use because my house never lost
power. And, NO to my good friend Carl Blare, my radios
didn’t all get blown away. (That’s another
funny Carl Blare joke, in case you didn’t hear it
or see it.) (Carl’s is going to write a
book that’s just a compilation of Part 15
radio jokes. So far, he and I have five.)
(I think it’s going to take a while to make
this book.)Anyway, I had one of these radios hooked up
to a 50 foot wire antenna and ground.Oh No! I couldn’t find any headphones! This
was completely wreaking my plan! The one
good pair of 2000 ohm headphones was missing,
and all of the others were broken. And, Ipod
type ear buds do not work at all, because the
impedance is completely wrong.Then the words AUDIO TRANSFORMER started popping
up in my brain. I grabbed the audio transformer
from the Part 15 13 MHz transmitter project. I
connected the 8 ohm side to the headphones and
hooked the other side to the crystal sets audio
out. There are many wires coming from the
transformer on that side, and I tried all of them
in every combination possible until I got the
loudest audio through the Ipod ear buds that I
had.Success! There was WTIC, the 50,000 watt clear
channel blowtorch coming in on 1080 kHz.I plan to replace the headphones for the crystal
radios very soon, but the transformer worked pretty
well with the Ipod ear buds in a pinch. The transformer
will go back over to the 13 MHz transmitter work bench
area, so it can be wired in when the time comes.If any of you guys have tried any thing like this,
I would love to know about it.Best Wishes,
Bruce, Dog Radio Studio 2
Total posts : 45366Sorry, I couldn’t find the edit button.
Bruce, DRS-2
P.S. OOOps – here’s another typo –
that’s AM band, not AN band.
Total posts : 45366Dog 2 Studio Radio:
Very interesting about picking the little crystal energy with no other power source. Be ready for anything.
Our joke book must wait until other Part 15 members have submitted their jokes. I had printed “pathetic” jokes, but I hit delete.
The fact that the Big Talker transformer came to your rescue is of course a superstitious thing, meaning that “it was meant to be.”
You may have lowered the impact of Irene by 1-percent.
Total posts : 45366Carl, I work two jobs, and one of them is
at a local supermarket.One of the cashiers is named Irene.
She was the recipient of several
hurricane jokes. I typed in the
word pathetic, too. But I hit the
delete button. Wait a minute, it’s
still there.Bruce, 2 Dog Radio Studio
Total posts : 45366At one time, back in the days when local grocery stores were run by local owners, the expression “Super Market” was new.
But two generations have gone by and we wonder what new people think of the term “super market.”
What about a “super radio station?”
Time for the delete key.
Total posts : 45366It is a very well known, much loved
analog AM/FM portable that is fairly
big, and takes 6 D batteries. It was
made by GE for many many years. There
are several versions.Now RCA makes it. I am very glad to
see that it is still around.By the way, on the crystal set, I heard
(at night with the 50 foot wire antenna);WTIC 1080 50 kW, Hartford, about 4 miles away
WRYM 840 125 watts, night, Newington, CT,
about 6 miles away
WPOP 1410 5 kW, Newington, CT, about 6 miles away
WDRC 1360 5 kW, Hartord, CT, about 5 miles away
WQBL834 1630 9 watts, about 1/3 mile away, in
West Hartford, CT and just barely,
W??? 1550 2500 watts night, about 7 miles away,
but with a 6 tower
directional array that is pointed away from
here at night. I can’t remember the call
letters, because they were just changed.The Litz Traveler can separate all of these
stations from each other.When I have the 150 foot wire up, I can hear WFAN,
660, in New York, NY, all day and all night. This
station is about 100 miles away.Best Wishes, Bruce, Dog Radio Studio 2
Total posts : 45366Bruce, your story tweaked my memory about my crystal set. My Dad gave it to me and it was a kit. I was about 6 or 7 years old and recall him and me working together assembling it. He insisted that I do the work and he read the instructions. I wound the coil with enameled wire on a paper cylinder. The top of the coil needed to be sanded to bare the copper for the sliding tuning metal strip. The crystal was a Galena chunk mounted in a lead pellet with the usual “cat’s whisker” arm. The earphone was a crystal (piezoelectric) type which was fairly sensitive and with an antenna strung across the room I could hear several stations. It worked pretty well.
Then came the enhancements. My cousin was an Air Force pilot and he gave me real headphones. These were not the usual tin diaphragm over an electromagnet type. These had a mica diaphragm connected to a variable reluctance movement mounted inside a magnetic yolk surrounded by a coil. These were so sensitive that if I touched the tip of the plug with nothing else connected I could hear 60 Hz hum induced from the power wiring in the house. These phones greatly aided in receiving weak stations.
Then I learned about grounds and antennas. We lived in a rural area with a wall crank type telephone so I used one side of the line as an antenna and the phone ground for the radio ground (the phone ring circuit used one line and the ground so they had installed a ground stake for the phone). Once I found the Galena sweet spot this radio really worked great. I didn’t know much about the danger of lightning but learned at about the same age when lightning hit the phone line and I watched an orange ball of plasma lightning came out of the phone mouthpiece, bounce across the room, and explode when it hit the TV set. Though at the time my radio was not connected to the line, after this I decided not to use the phone line as an antenna.
Neil
Total posts : 45366I can only stay a minute because I
have to go to work, but wow –isn’t that plasma thing also known as
ball-lighning? Oh man – I would have
been scared to death!For crystal radios – I still use the
little ceramic ear pieces. They don’t
last for ever. You have to replace
them once in a while. They say if you
can get a sound powered earphone from
World War 2 surplus stuff, they are
great. After I get all of these Part 15
projects done, I want to build a few
ham QRP transmitters. Then after that –
it would be a super-duper crystal set.I llke the ceramic earplugs because they
are loud and really inexpensive. They aren’t
the greatest, but the price is right.I night have a few other comments later. Your
story is really something!Best Wishes,
Bruce, Dog Radio Studio 2
Total posts : 45366If anybody has built a WAVE TRAP
for a crystal radio to help knock
down the strength of local stations,
I would love to hear your experiences.Also, I received one more station with
the Litz Traveler crystal radio today
on the 50 foot wire antenna.910 WLAT 5 kW, Farmington, CT about
5 miles away. Their pattern
fires away from me at night,
but they come in during the
day OK.So that’s 7 local stations. No too bad
for an unoptimized setup.Bruce, Dog Radio Studio 2
Total posts : 45366If anybody has built a WAVE TRAP
for a crystal radio to help knock
down the strength of local stations,
I would love to hear your experiences.Also, I received one more station with
the Litz Traveler crystal radio today
on the 50 foot wire antenna.910 WLAT 5 kW, Farmington, CT about
5 miles away. Their pattern
fires away from me at night,
but they come in during the
day OK.So that’s 7 local stations. No too bad
for an unoptimized setup.Bruce, Dog Radio Studio 2
Total posts : 45366I often found using that technique would not only help dampen the strong local signals but also affect the sensitivity as a whole even to the weaker signals I was trying to pick up.
I resorted to simply making the cat whisker unit narrow band in its range of tuning and built several to cover different sections of the band…solved the problem…plus it killed time making all the other sets customized to pick up specific sections of the band.
Sure was fun!! Still is!!
RFB
Total posts : 45366Yup. I can get a bunch of
gelena (sp?) no problem.So do you just make one
big coil and use a small
tuning cap for a certain
portion of the band? Or
do you take a 365 variable
and put a cap across it or?Too bad crystal’s aren’t cheap.
They would make a good sharp
tuned circuit. I suppose if
you had one particular station
that you really wanted to hear(?)The AF4K website does have cheap
crystals for the AM BCB. Not
having your knowledge, I am really really
in unknown territory here.Are you able to give me a few small
details on how you did it?Best Wishes,
Bruce, Dog Radio Studio 2
Total posts : 45366Best method was simply winding the coil specific to a given portion of the band. To further enhance the lower band sets, the coils would be large in diameter and winding count, and the mid to upper portion with smaller diameter coils. Sort of a “front end selective resonance tank” for each segment of the band. Variables were used as fine tuning more than direct tuning. A sliding contact arm across the coil was best for the direct tuning.
Naturally a very strong signal is gonna bleed through depending on how far away it is simply because a crystal set utilizing the energy of the radio wave itself..is not enough juice to power circuits like that found in IF sections of regular radios where the bandwidths can be finely tuned.
You can also try using a rusted razor blade and safety pin in place of the crystal, or the infamous germanium diode. A small cup of iron and copper filings will also work. A wide variety of different materials can be experimented with for the crystal.
Different materials will produce different results in both sensitivity, selectivity and frequency.
RFB
Total posts : 45366Well, I’ll probably have to make a
DX crystal set from scratch.You advice is very helpful.
I’ve got about 5 projects before that.
But the magic of the whole idea has always
made a big impression on me, ever since I
was about 7 years old.And when I was a kid, WDRC 1360, WPOP, 1410,
and WTIC, 1080, all in the Hartford area,
were really fun to hear. DRC and POP were
top 40. And TIC was just a great full
service station.Thanks again,
Bruce, Dog Radio Studio 2
Total posts : 45366Your welcome Bruce! I hope I have info everyone can find useful. 🙂
I spent hours peaking and tweaking those resonance tanks for my crystal sets. I even made one that was “universal”, where the different coil tank assemblies would simply plug into the set and with a minor adjustment to the slide arm contact, one main set with detachable resonance tanks for selective band listening.
One thing I really enjoyed about that last set I made was that I recovered a ton of radio bench space! 😀
RFB
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