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Post by Admin on Sept 18, 2019 1:51:23 GMT
Digging through some of my yesteryear toys I pulled out of the pile the circuit board for a Remco Caravelle.
Anyone remember that toy from 1962? It was a George Jetson looking cabinet, sky blue and when you're 10 old years and fascinated by radio it's really cool.
It is a combination AM regen receiver and AM transmitter. It has a desk mic and a telegraph key. Would transmit about 100 feet, voice and keyed tone, with a 3 foot rod antenna.
Anyway, I had one way back then and a few years ago bought a couple from Ebay as well as the spare circuit board.
I recapped the board and tried it out. Not bad for a 3 transistor free running oscillator RX/TX almost 60 years old.
I have so much old stuff like that. I need to setup a museum so I can make some room here...
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Post by station8 on Sept 20, 2019 17:31:48 GMT
Howdy Bob:
A blast from the past, wow some good ole stuff!.
I have some stuff or schematic from the blast from the past as well.
1) Graymark 533 am transmitter ( 4 + 3 manuals & schematic )
2) Radio shack Science fair kit ( 3 + schematics)
3) Mox Vox am tx ( complete in great shape missing manual )
4) LPB am tx (mint condition )
I been trying to collect old am tx when I had extra money
But things has changed!.
Station 8
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Post by thelegacy on Sept 21, 2019 20:00:41 GMT
What would happen if you were to make an ATU and put a 10 Ft antenna on it? I wonder what would happen then.
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Post by Boomer on Sept 25, 2019 0:31:45 GMT
I started with a Science Fair AM Broadcaster, nice, though it didn't have the bite of the older kits as far as range, I found it hard to get outside of the house with it. I envied those starting with Knight Broadcasters, but you can't beat a radio station for less than ten dollars when you're a 12 year old. I think I got mine as a gift and didn't even have to earn for it.
I've seen info about the Caravelle, they did nice things with a simple circuit. All of those old AM beginner transmitters were just tuned circuit oscillators, and not all that stable to begin with, and had incidental FM that happened along with the AM, and that limited the loudness you could get out of it.
Legacy, I wonder if your idea of ATU and 10 foot radiator would help the stability. If the high-Q series coil was coupled to the oscillator's tuned circuit coil, it might help to stabilize the oscillator so it wouldn't 'FM' as much. We'll have to look into it, to help those with vintage gear like Knights and Science Fair.
Boomer
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Post by mark on Sept 25, 2019 0:41:33 GMT
Posted a picture of this.....nice. Didn't know they made a transmitter like this back then. A radio and transmitter together. How did it sound with music?
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Post by Boomer on Sept 25, 2019 2:44:24 GMT
Thanks WMRK, that looks sweet.. like a real control center with class, even the plaque that carries the Caravelle name is shaped like a AM modulated carrier.
Any kid into space shows like Jetsons and Lost In Space would love to sit at their very own command center like that, I can picture it myself.
I'd also be interested in what kind of range it has, type of antenna and things like that. Can you use the code oscillator out over the air and broadcast CW?
If you had a friend with another unit like it, you could do two way communication with them.
The only thing I could think of that would be close would be the Radio DJ with cassette player and attached mic that was made to look cool. It broadcast on 1610 AM, and doesn't have a receiver in it.
Boom
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Post by End80 on Sept 25, 2019 4:14:33 GMT
Posted a picture of this.....nice. Didn't know they made a transmitter like this back then. A radio and transmitter together. How did it sound with music?
Didn't realize it was a receiver too. There's a story about that transmitter I find kind of interesting - It was what Rush Limbaugh used for his first broadcast experience, as a kid he talks about it in his book "An Army of One". Also about 10 years or so ago when he was a guest on William Shatners (Captain Kirk) show called "Shatner Raw Nerve" on the Biography Channel, Rush presented that Remco transmitter to Shatner... 
SHATNER: You brought something with you here you wanted to show me to discuss.
RUSH: I did. My parents, despite what I told you earlier about being frightened of my being on the radio, gave me this for Christmas when I was nine years old. This is a Remco Caravelle, and it actually transmits —
SHATNER: It transmits?
RUSH: It transmits on an AM frequency of your choice for 500 feet. And I would take this up to my bedroom and play records and play deejay —
SHATNER: To the house.
RUSH: — to the house, and my mother and dad would sit down and listen to me. It sounded like — the quality was horrible, but I was on the radio.
SHATNER: And did they indulge you?
RUSH: They gave me this for Christmas.
SHATNER: Isn’t that something. Let’s give little Rushie a prize which he’ll grow out of and go on to college. We know that he will.
RUSH: I had quit the Boy Scouts and the Cub Scouts. I was a quitter. I’d quit everything conformist I was supposed to do. This is the one thing I didn’t quit, radio, so they indulged me, “At least he’s showing some stick-to-itiveness.”
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Post by station8 on Sept 25, 2019 13:45:43 GMT
Howdy y'all:
Here are some classic kits I had!,
I had the radio shack science fair kits
28-209 this am tx I got to go pretty far about 1-3/4 mile antenna was 20 feet in air NO GND!.
( Output transistor was capable of only 50 mw top end ).
28-103 ( p kit is) tx I got some range it was not as far but I did not try other antennas I had
To see if I would get more range!. ( No gnd ).
I did this back in the late 70 to early 1980 in the test!.
I also had a Graymark 533 am transmitter too this a nice kit !.
Your tuner and antenna will make or brake you in range and signal
Do NOT let anyone tell you different!.
All there trying to do is discourage you from the hobby!.
If your NOT getting range it should also tell you your
Doing something very WRONG!,
So STOP take a breath and look a different aspect to fix the
Problems and take notes!.
Have fun with the hobby
Station 8
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Post by Boomer on Sept 26, 2019 2:00:32 GMT
Range
We all need more range, you're not kidding Station8! It's the holy grail of Part-15.
I didn't have range on my Science Fair, it was about 40 feet seriously!
The signal was blasting loud in the house and I thought all the neighbors would be listening, but when I went outside with a portable radio, I was in for a rude surprise, the signal dropped to almost zero, I could hardly hear it a few feet from the house wall.
I never tried the Science Fair's antenna outside of the house though, that's where you get the range.
I did get range though, when I wrapped the antenna wire on the kit around my mother's phone.
The signal then went down the street for a few houses at least, by a form of 'phone line carrier current' I found out. I didn't do a full range test though, I think I was playing records and had to get back before the song ended.
I had seen that there were a few Science Fair transmitter kits, I think the cost was as low as $2.95 for the P-Box version with 1 transistor, where I had the later deluxe version I guess, 3 transistors and a box coil you wound yourself, and a tuning capacitor to change the frequency.
Every one of the Tandy 'Electronics Labs' must have had an AM transmitter in it too, and I built those as well.
Boomer
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Post by station8 on Sept 26, 2019 3:18:01 GMT
Howdy y'all:
What I found with classic transmitters is that there like the new transmitters as well
You to know your tx output circuit very well then make your antenna accordingly!.
If your signal drop quickly you have a serious issue on matching and did a
Big boo boo and back to the drawing board you go.,
I found aluminum siding homes are the worst for the tx to get out
It happen with me in our old house we lived in I also finding out
Here with are 6 foot high galanvised chain link fence it effecting
My signal and range as well
Once I moved my 28-209 50 feet away from house put antenna up 20 feet
I could go to our mail box 300 feet away and had a full signal on my ge radio
I could go to my grandmother house at 1/4 mile away and on her ge radio day or
Night you could pick my station up clear on 1610 am
I like the classic tx they seem to be better like a time x watch!.
It's a shame slot of the company's are gone now
Have fun
Station 8
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