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  • November 14, 2019, 12:55:53 PM

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Author Topic: Some Unusual History  (Read 3258 times)

Online FLOYD CARTER

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Some Unusual History
« on: August 13, 2019, 05:16:41 PM »
I think it was in 1956.  I lived in Downey, CA and not far from Bob Dunham's fledgling ORBIT R/C business, which was run from his home.  Bob asked me to come over and share ideas on R/C equipment.  He wanted to produce a ten-channel R/C outfit, but he was having trouble getting his receivers to work properly.  Well, I ended up re-working his receiver design to make it more sensitive.  At the time, all radio control stuff was operated with tuned reed banks.  A 10 channel reed bank would control five servos.  I bought the best reed bank I could find, and built this receiver for Bob.  He later changed some of my transistors to smaller ones and he had a printed circuit board made up.  I never learned how many 10 channel radios he finally sold, but must have been quite a few.  The best servos made in those days were by Howard Bonner.
"Growing old is easy.
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Offline Shorts,David

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Re: Some Unusual History
« Reply #1 on: September 12, 2019, 11:24:36 AM »
We're those the radios that if you yelled at just the right frequency you could make the service move? I started rc about 82, when everything had moved to 72 mhz.
How about c/l, what was your first plane?

Online FLOYD CARTER

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Re: Some Unusual History
« Reply #2 on: September 15, 2019, 10:34:58 AM »
Reed transmitters had 10 audio tones modulated onto an RF carrier (Amplitude Modulation).  Each audio tone activated a resonant reed on the receiver reed bank.  Each reed had contacts (like a relay) connected to a servo amplifier.  A small current passed through the reed contacts to the servo.  Two tones per servo, like elevator--up and down--and absence of any tone command caused the servo to return to neutral.  There was no "trim".  Servo trim had to be adjusted on the ground by adjusting linkage.

Reed type servos required three separate voltages;   + 3 volts,  - 3 volts and  - 1.5 volts.  The battery pack was SEVEN cells, either alkaline or NiCd.  Quite heavy!

The transmitter had 10 buttons for control.  Or else  five "telephone type" lever switches.  Controls were either Neutral, or else Full Control, one side or the other.  "Proportional" control could be simulated by pulsing the switch On and Off rapidly, causing the control surface to "dither" between neutral and full control.

Managing a reed bank R/C was much more difficult than the later Proportional radios.  Precision R/C flying was nearly impossible.

My first C/L plane was an old free flight model converted to C/L.  It was called "Spook 48".  That was 1945.
"Growing old is easy.
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AMA #796  SAM #188  LSF #020

Offline phil c

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Re: Some Unusual History
« Reply #3 on: September 17, 2019, 06:12:03 PM »
I had an Orbit 10 channel reed set around 1970.  Was getting into RC for something different, while building combat planes for fun.
I actually flew a plane with it.  There were still some very helpful guys in the Twin City club.  Some were still flying reeds, digital proportional was just getting affordable.
I remember one time watching one of the better flyers flying with a reed setup, and somebody else had the back of the transmitter off, re-tuning the reeds so it could be landed.

Later on I built a MAN outfit and learned to land.  Initially though it was exciting.  One kind of windy day I was having problems keeping the plane pointed upwind back to the field.  It finally got so far away I could barely see.  The best all around flyer in the club grabbed the transmitter and another guy had binoculars and was telling him which way to turn to keep it coming back.  The controls are reversed, so it's tricky.  They did manage to get it back in one piece to a nice landing, than God.  More money than I could afford to lose.
phil Cartier

Online FLOYD CARTER

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Re: Some Unusual History
« Reply #4 on: September 19, 2019, 01:02:24 PM »
Phil.  A 1970 Orbit 10 channel reed outfit might have been a later revision of my original circuit.  I'm not sure who helped Bob Dunham with later electronic design.  Bob was not capable of electronic design.

For those who might have known Bob Dunham, he died of lung cancer.  He smoked almost constantly.

One of my own early home brew R/C outfits was a 10 channel reed system with a very large transmitter.  It was often necessary to weekly re-tune the audio generators in the transmitter because they would drift slightly, and the reed bank in the receiver was very narrow-band.  Just a few cycles off frequency and the reed would not vibrate!  It was common to lose one or more channels while flying due to circuit drifting.  Crashing in those days was common due to radio problems.
"Growing old is easy.
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AMA #796  SAM #188  LSF #020

Offline dennis lipsett

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Re: Some Unusual History
« Reply #5 on: September 19, 2019, 01:47:16 PM »
Phil.  A 1970 Orbit 10 channel reed outfit might have been a later revision of my original circuit.  I'm not sure who helped Bob Dunham with later electronic design.  Bob was not capable of electronic design.

For those who might have known Bob Dunham, he died of lung cancer.  He smoked almost constantly.

One of my own early home brew R/C outfits was a 10 channel reed system with a very large transmitter.  It was often necessary to weekly re-tune the audio generators in the transmitter because they would drift slightly, and the reed bank in the receiver was very narrow-band.  Just a few cycles off frequency and the reed would not vibrate!  It was common to double 1 batteries labolose one or more channels while flying due to circuit drifting.  Crashing in those days was common due to radio problems.

In 1967 I was at the far east nationals in  Tachakawa AFB Japan. It was an armed service  contest with a chance to go to the nationals in the USA. Bob Dunham and Zell Ritchie were the C.D.'S of the Meet. I was still flying single channel R.C with an upgrade to Royal servos and combined with a receiver and 3 servos and 11double A batteries soldered in the appropriate voltages for each function made for an interesting heavy set up. Transmitter was a Hinode which had a system that beeped every time time you keyed the button. Made it easy to count out the pulses to get the right control movement
   To the point I had 2 really informative chats with both Bob and Zell and they were gracious enough to spend time answering my inquisitive questions. Mr Dunham asked why I did not have an Orbit outfit and I had to answer that I would love to have one but at $435.Dollars plus an additional $35.00 for the 4th servo precluded my owning one of his radios until I left the service and got a good paying job as the service was starvation wages. That was when Orbit made the 3+1 analog radio
I never did get one as I built a few World Engine radios, Heath and Royal  also when I got out.
But I fondly remember the 2 of them and their enthusiasm  for the hobby.

Online FLOYD CARTER

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Re: Some Unusual History
« Reply #6 on: September 19, 2019, 06:01:11 PM »
Possibly not many are familiar with the name Bob Dunham.  But since I breought it up, and there were responses,  I'll fill in a bit more.

Bob Dunham, of course, was best known for starting and operating Orbit R/C products.

He got into R/C, but he was first a C/.L flyer.  I first met Bob in 1947.  We were both charter members of a new model club called "South Gate Skylarks", located in (what other?) South Gate, CA, a suburb of south Los Angeles.  Another charter member was Tom Lay Jr.  Tom's dad and uncle were C/L flyers, too. Tom Lay Jr. was just 9 or 10 at the time, but he could fly control line.

Anyway, Bob Dunham flew mostly speed models in the late '40s, and did OK at stunt.  In the mid '50s, Bob Dunham and I lived in Downey, CA about the time he began Orbit R/C.  He got me to look at a design for R/C receiver and transmitter.  I made some changes to his schematic diagram and I then built a receiver for testing.  His transmitter design seemed solid, so I didn't try to change it.

By the time I had finished college and I moved away, I lost contact with Bob.  When I finally wrote a letter many years later, his wife wrote back about his passing.
 
"Growing old is easy.
 Staying old is hard"
AMA #796  SAM #188  LSF #020

Offline Larry Renger

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Re: Some Unusual History
« Reply #7 on: September 21, 2019, 08:38:34 PM »
For about $120, now, you can buy a park flyer that would blow any of that stuff away....in spades! We have come a long way.
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Online bob whitney

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Re: Some Unusual History
« Reply #8 on: October 04, 2019, 10:04:07 AM »
in 1966 Bob Dunham and John Brodbeck were the C/D'sat the Tachakawa meet.after the contest was over Bob was putting on a show and I talked him into letting me fly his plane that was quite a thrill. .Brodbeck asked me why I was using S/T's I told him that was all I could get. when I got back to Hawaii there was a K&B 15 and 29R waiting for me.  both great guys

rad racer

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