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Some early digital proportional history

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Some early digital proportional history

Old 09-29-2007, 09:46 AM
  #51  
ukengineman
 
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Default RE: Some early digital proportional history

Encoder of the F&M Digital 5 was self starting. Red button was battery test on the meter. Cost of the early proportional gear was extremely high in real terms back then.
Old 10-05-2007, 01:52 PM
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jaymen
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Default RE: Some early digital proportional history

The modulation was the same on most post 1965 transmitters, but the frame rate, and neutral pulse width did vary on some models. 1.5 milliseconds and 1.7 milliseconds was used for the neutral pulse width, hence some servos will not quite center, but you can adjust the servo feedback pot to solve this.

On the AM stuff, as mentioned above, a pulse reverser like Ace, Royal, and McDaniels sold works fine. My servo cycler has a reverse pulse switch too.

The F&M Digital 5 had Digimite servos, failsafe type, Bonner circuit boards, I have one. There are 32 little balls in there, take it apart in a shoebox, or spend hours looking for them....... Yes, they are real slow. A split supply of plus and minus 3 volts(6 volts total) helps a little. The Bonner 4RS had 4 wire plastic cased, harmonic drive servos, but they too were slow. I had one recently, NIB, but sold it on eBay as it was just too flakey to deal with.

Sorry, I got confused, it is on FM receivers that the modulation pulses get reversed with high, or low side crystals....too many types of radios and I get crossed up!!

I should have know the difference between a Slylane and Skyhawk...having flown them in flight school, but I guess I'm slipping, there is no future to this old age thing!


The Sampey 404, and the earlier Astronics had a "start" button to kick off the ring counter, pretty crude but it was state of the art back then.

I heard recently that Bob Dunham had a little Taiwanese honey on the side, she worked at that bar in Garden Grove. He used to make alot of trips to the orient....hmmm, what was he up to??
Old 10-21-2007, 10:49 PM
  #53  
HighPlains
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Default RE: Some early digital proportional history

Well Russ, I guess that I will try your scheme of flying a modern airborne with a vintage transmitter. I picked up a '66 Kraft transmitter that's on 27 MC recently. I guess it will work with a Futaba R124H four channel AM receiver. I think I will replace all the electrolyic caps, redo all the internal wiring to the pots and battery, and add a new battery pack. That and redoing the logo, and it should work as good as new.
Old 10-22-2007, 12:13 AM
  #54  
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Default RE: Some early digital proportional history

High Plains, funny you should mention my idea - I flew the Shoestring this afternoon for the first time in four months with the 1970 MRC (Futaba) F-700 TX. Solid, flawless performance. The sticks are longer than I'm used to today, which gets a little crampy after a while.

I would be careful using the Futaba R-124. I tested one last year in the Wingo guinea pig. It had slightly less than half the ground range of the older R-114(now discontinued) about 90 feet compared with 200 feet for the R-114 with the Citizen-Ship DPT, antenna down. I flew it anyway, practically out of sight with no glitching, but I would check it out in some POS airplane first. Futaba only claims a range of 600 feet, but that's what they said about the R-114 and it's definitely a full-range receiver.

The R-114 AM is the way to go, but it's hard to find now. BUT, the HPI RF-2 receiver is in production and is an R-114 built for HPI by Futaba. I've used one and it works fine. Thanks to Frank Schwarz for sending me one for flight test. Ebay seems to have RF-2s all the time, and they can be had from Horizon Hobby new for 40 bucks, from A Train hobbies for 35.

Even as we speak, Ron Ellis is restoring a super clean Heathkit GD-47 TX I got off a certain auction site. From 1968, I think it was one of the last radios to use Bonner sticks.

Is your new Kraft identical in appearance to the metal box one you have on 72? What stick assemblies? Pictures please! Russ Farris
Old 10-22-2007, 12:43 AM
  #55  
HighPlains
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Default RE: Some early digital proportional history

Thanks for the receiver tip. I'll get the HPI RF-2 then.

The Kraft is a single stick with the rudder on the top rear of the case, rudder trim next to it, and throttle and trim on the right side. It needs the logo reapplied and a new handle on the stick for cosmetic restoration. Here is a picture from an old Kraft ad, and a picture of it next to the the two stick Kraft.
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Old 10-22-2007, 01:05 AM
  #56  
maxpower1954
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Default RE: Some early digital proportional history

Pretty neat, HighPlains! I don't think I've ever seen an control arrangement like that before. I would find that awkward to fly...Russ Farris
Old 10-22-2007, 01:13 AM
  #57  
HighPlains
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Default RE: Some early digital proportional history

Yes, I have to agree that it is awkward but possible. I certainly liked my series 70 Kraft single stick much more, as I flew with it for about 10 or 11 years. I've still got it in the original packing crate. What switched me over to two stick was pylon racing when I finger glitched the rudder during a turn and planted a plane. The "salad bowel" stick worked great for sport flying.
Old 10-22-2007, 04:10 PM
  #58  
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Default RE: Some early digital proportional history

What a neat pair of old Krafts, Highplains!
Old 10-23-2007, 09:05 AM
  #59  
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Default RE: Some early digital proportional history

The thing I have against the R114 is that it is only four channels.

I tested my F&M transmitter on it and verified that the first channel is actually dead (unused). That means I really need a six channel Rx.

The R114 decoder could be modified for additional channels, but it's not a real easy task....a bit of a hack. I presume from what you say, Russ, the HPI is the same.

It would be really nice to have a good dual conversion 6-8 channel 27mHz receiver. I had hoped Silvertone would have one, but even theirs is single conversion and a bit pricey.

[link=http://www.silvertone.com.au/mark22-smrx.htm]http://www.silvertone.com.au/mark22-smrx.htm[/link]

.....Edit: Maybe not that bad, though. My calculations put the price at around $112 American, and they do claim 10kHz bandwidth.
Old 10-25-2007, 02:08 AM
  #60  
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Default RE: Some early digital proportional history

Highplains,
I used to fly one of those Kraft single stick radios, every component of the system was gold anodized. The stick you are referring to was a aluminum rod drilled and tapped then attached to the assembly. As I recall it was maybe about three inches long, rounded on the end and anodized red. Got pretty good at coordinating rudder and aileron. Now that I think about it, the stick was probably one of the type used on the two stick radio but without the thumb grip. That was for the guys converting over from reeds who would fly proportional with their thumbs. Orbit did it right with the three axis single stick control. Finally, Kraft introduced the three axis stick with the introduction of the Gold Medal system in 1968.
Old 10-25-2007, 08:14 AM
  #61  
HighPlains
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Default RE: Some early digital proportional history

Thanks Michaelj2k. I have not found any good pictures of the transmitter, except for ads showing the Bonner stick assembly instead of the open gimbal. Any idea of the diameter of the rod, and was it tapered?. I suppose the anodized red was to match all the other levers.

The two stick has a ID plate on the bottom like all the later Krafts, with a serial number 2262 engraved on the plate. Due to the servos (KPS-9), it must have been produced at the very end of the series. The single stick has a sticker inside with I think (very very faded) typed on it the serial number 542. Not too many produced over a two year period, but I would think the single to be fairly rare.
Old 10-25-2007, 08:08 PM
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Default RE: Some early digital proportional history

Yup, I think it is a rare transmitter as everyone flying pattern preferred the Mode 1 or 2 two stick open gimbal radio while the single stick was sold to the sport flyers. As far as the stick diameter, the rod was a constant diameter, maybe 3/16 inch to 1/4 inch and from 3 to 4 inches long. It's been a long time and I'm not exactly sure but the dimensions are ballpark.
Old 11-02-2007, 04:19 PM
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Default RE: Some early digital proportional history

Lots of good information on this thread! I fly a Bicentennial Series
7 channel Kraft system regularly, 72 mHz & 53 mHz. Hope I never
have to give up the yellow tx's for new technology!

Kenny
Old 11-12-2007, 12:35 PM
  #64  
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Default RE: Some early digital proportional history

Maxpower1954,
You could try doubling the antenna length on that Futaba AM Rx. I believe it was intended for cars, so Futaba only gave it a half of an antenna.
That Rx is 1st choce for others using old 1960's vintage propo transmitters.
Old 11-12-2007, 10:30 PM
  #65  
maxpower1954
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Default RE: Some early digital proportional history


ORIGINAL: boberos

Maxpower1954,
You could try doubling the antenna length on that Futaba AM Rx. I believe it was intended for cars, so Futaba only gave it a half of an antenna.
That Rx is 1st choce for others using old 1960's vintage propo transmitters.
Yep, that was my thought as well, I did notice the R124 was about half the length of the R114 antenna, but I have two R114s and one RF-2, which is plenty for my vintage transmitter fleet. I'll try a full length antenna in my testbed Wingo sometime. Russ Farris

Old 11-13-2007, 02:17 AM
  #66  
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Default RE: Some early digital proportional history

Great reading guys! Brought back some memories. I came into this hobby just before the Ghosts Galloped up on the scene. I wanted a radio in the worst way but three kids literally ate up all my loose change so it had to wait. When Galloping Ghost radios came out with a price in my area I made plans to save some loot and get one. Before I got started saving for my GG, RCM ran the piece on Portportional radios that we could put together ourselves. That peaked my interest.

I read it through, but didn't absorb a great deal, but I wanted one. Then the writer of the piece, can't remember his name, began to sell Transmitters, Receivers and Servo parts for self assembly at a reasonable price, so my savings were Retagged for a RCM radio. About that time I saw a Heathkit ad about a 3 Channel Porportional radio kit, and it could be purchased "On Time!" I sent a money order for my first payment right then! They also offered a 4th Channel Conversion kit and I ordered that. This radio was that Vertical "Walkie Talkie" looking set, with a Single Stick configuration.

In a few weeks I was well into assembling my first Portportional RC rig, and a 4 Channel at that! The 4th Channel was added to the top of the Single Stick via a knob with a Pot inside. This became the Rudder. The stick itself controlled the Ailerons and Elevator. The radio sat in you hand which passed through an Elastic strap underneath. The middle finger of the left hand fell over a Trim type lever on the right side which was the Throttle. Very comfortable. I put in a lot of airtime with it over the years until it was outmoded.

A friend had assembled a World Engines 4 channel with a Single Stick about the same time. When he saw my Heath, he had me order the Heath Stick and Pot Add Ons and it fit the WE hollow stick just fine. He then had the identical control set up as on my Heath. He had a left over stick on the left side which was unplugged and unused, but he learned to live with it, as he like the single stick mode as I did. Reminded us of the stick on a J-3, so we learned to control our models a lot faster in that mode. I eventuall learned to fly two sticks when I began to Instruct others who were bringing me their 2 stick Airtronics. Had to learn to fly them before I could teach them! But we had fun, thanks to the guys who put all that wonderful stuff together for us to play with.
Old 11-19-2007, 04:53 PM
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Default RE: Some early digital proportional history

Did anyone ever mention that the single stick (open gimbal) were all about the same size. I went to a contest in Alexanderia (sp) LA where I saw Jim Kirkland, Lou Penrod and Ron Chidgey all flying Kraft single sticks. They all had an impact on R/C. Super people. The last job Kirkland had was with World Engines. During the finals at the NATS I was a flight line controller. Two line of 5 airplanes each. Marty Barry was the first in line and Jim Kirkland was the last. As the flying went each flyer was in front of a different set of judges. Anyway, Kirkland was flying and Marty was up on the other flight line. I put Marty on the clock and he turned on. Only problem was that Marty and Jim were on the same frequency but did not have any flags on their transmitters. Jim threw his transmitter across the runway as he thought it had quit on him. I don't know if he ever found out because he died that winter. Marty and I talk about that anytime we meet. By the way, they were on 6 meters and I fly on the same so if there had been flags on their transmitters I would never had put Marty on the clock. Memories.

Dwayne
Old 11-28-2007, 09:21 AM
  #68  
HighPlains
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Default RE: Some early digital proportional history

The reason that you have trouble using the Futaba R-114 is two fold: The sync pause/reset time for the earlier systems was different, as was the frame rate. Changing the sync cap in the decoder will solve that. Additionally, the Futaba receiver outputs a positive pulse to the servo. Some of the early systems used a negative pulse to the servo, so a pulse inverster would be needed...Ace R/C used to sell them. The other option would be to get a Receiver crystal that was cut 455 Khz higher that the channel frequecy for the Futaba(high side as opposed to low side crystal) to invert the pulse train going to the decoder.
I was thinking a bit about this Jay, I don't think changing the crystal frequency from low to high side would have any effect on the decoder output (ie. changing negative pulse to positive). However it should be a simple task to find the AM detector diode and reversing it to do pulse transformation.

On the other hand it's early in the morning and I'm not really awake yet.
Old 11-28-2007, 07:11 PM
  #69  
jaymen
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Default RE: Some early digital proportional history

Yeah, I must have had too many beers, would you not say!!! That only applies for FM, not AM, I think somewhere above I tried to correct myself, but alas..............

Speaking of beers, I have received a couple complaints about quoting people I interviewed on the more human side of certain r/c pioneers....it seems they have been offended by it. My take is that the human side is what makes a story interesting and the people in it real, not just some idolic gods, but a real people with the strengths and weaknesses we all have. I could appease the minority at the cost of denying the majority and just delete , or edit my posts above...but I think there are enough here who have enjoyed it so it will stand as it is.
Old 11-28-2007, 07:39 PM
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HighPlains
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Default RE: Some early digital proportional history

Well when I was studying electrical engineering, most circuits started out on bar napkins. One of the professers always converted the price of new IC's into the number of pitchers of beer we would have to give up to buy the part (back in the early 70's).

Engineering without beer? Unthinkable! (for almost anybody in their twenties and thirties).
Old 11-28-2007, 11:11 PM
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Default RE: Some early digital proportional history

Hello:
I have been folowing the F&M transmitter/Futaba Reciever incompatibilites. I have an F&M transmitter/Futaba Reciever. And know enough about electronics to be dangerous... I am an engineer and like to learn as much as I can. Ok...I know the transmitter "pots" feed into the encoder, the encoder puts the signal into pulse train with a sinc pulse then a varible time pulse for each channel depending on the position of the transmitter stick. This gets transfered onto a carrier which goes to the reciever. The reciever detector gets the signal and sends it to a decoder section and then syncs with the sync pulse and decodes the information. This decoded information is then sent to the servo by a signal telling the servo where to go. (If this is wrong let me know). For a new style reciever this is a dc pulse of .5 Volts that varies from 1ms to 2ms with 1.5 being the center that pulses every 6ms(I looked at it on my scope). If I am wrong on this please let me know.

Ok, from what I can tell the sync/pulse reset time is basically the first signal from the transmitter to the reciever. So one could either change the timing on the reciever or the transmitter? Also the Neg vs Pos pulse could be changed by reversing the diode detector in the reciever. So basically I would have to change one cap in the reciever changine the frequency of the detector and then reverse the diode making the pulse opposite from what it normally comes off. Is this what you guys think it would take to make them compatible?

Are there points in the reciever to pull the signal off the reciever so I can look at it? I guess I can just probe around but was wondering if they had factory points between the rf section and the decoder section.

Any help would be appreciated.
Steve
Old 11-28-2007, 11:40 PM
  #72  
HighPlains
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Default RE: Some early digital proportional history

that pulses every 6ms(I looked at it on my scope).
I'd recheck the scope time base. 6 ms sounds to fast for the frame rate of any transmitter. Maybe it is the time for the sync pulse, as they were in the 4-8 ms range.

There were also two different modes that systems operated with. One was a fixed frame rate, while the other had a variable frame rate. Both systems had advantages and disadvantages. Here are a few:

Fixed frame rate systems gave better servo performance. This was because the pulse stretcher circuit in the servo could be optimized for an exact frame rate. However, the receiver had to contend with a variable width sync pulse, and if all the channels were giving the minimum pulse outputs, this could be quite a long time (especially with more than 4 channels) or a very short time with maximum pulse widths. A large part of the problem is getting the time constants correct so the receiver can properly reset.

Variable frame rate systems always had the same length of sync pulse, so the receivers were more stable. If minimum pulses were send out, then the frame rate was quite short, and servos might start to buzz a bit because the pulse stretcher inside the servo would not have time to completely discharge before the next control pulse reached it. This caused high current drain (shades of digital servos). If the pulse stretcher was configured to avoid this one condition (all minimum pulse widths), then the servos tended to be very slugish when the frame rate slowed down (all maximum width pulses).

Ah, the joys of system engineering in the ANALOG WORLD.

I'd start at the decoder and work backward (especially if it has a simple IC decoder).
Old 11-29-2007, 11:21 AM
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Default RE: Some early digital proportional history

There have been some queries refering to the F&M Digital 5 Tx and its use with a modern Futaba AM Rx. As I have been working on this project the following may be of interest. Back in the 1960's I had a Digital 5 and I have recently aquired another identical system which I am restoring. grotto2 also has one and we have exchanged useful information. I have the Tx fully operational and have a jumper which enables choice between F&M mode and Futaba compatible. The frame rate is fixed at 35ms which is OK for the modern Rx. Although 5 channels, 7 are actually transmitted the first and last are fixed length guard pulses and are part of the F&M Rx failsafe system. The first pulse shifts all the others along one so as grotto2 has pointed out you would only get 3 channels from a Futaba R114. Also the first guard pulse on my Tx is very long and causes the Rx O/P's to jitter. In the F&M Tx all the pulses are diode OR'd together to the gap pulse generator. A good tip from grotto2 is to lift the first diode (I have a jumper here) in the chain which removes the first pulse. The R114 then works happily giving you motor, aileron, elevator and rudder - you just lose the aux channel. The Bonner Digimites worked on a 1.7ms centre so for use with modern gear you will need to make this 1.5ms. On the F&M Tx PCB there is a master trim pot for each channel and they can easily be adjusted to 1.5ms, these pots are quite fierce in their adjustment. I have attached (hopefully!) some waveforms of the Tx envelope, one shows a complete frame (about 35ms, display 5ms/div) another shows the 7 pulses in F&M mode (2ms/div) and the remaining one shows the first pulse suppressed for use with a Futaba Rx (2ms/div). The 5 channels are centred on 1.5ms. I hope to fly at some of the UK meetings next summer using the F&M Tx with a Futaba R114 or HPI RF-2 Rx.
Alan
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Old 11-29-2007, 10:58 PM
  #74  
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Default RE: Some early digital proportional history

Thanks for the information on converting the F&M transmitter to work with the futaba reciever. I opened up the transmitter and this is what I saw. Of course since I am an aero engineer and not an electrical I am as normal confused. A couple of questions. 1. Where is the diode that you are talking about on the board? 2. Where are you hooking up the oscilloscope? Er..this may be a little off topic but I think it would give at least me a place to start to figure out these old radios. Thanks for your time.

Steve


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Old 11-29-2007, 11:43 PM
  #75  
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Default RE: Some early digital proportional history

I don't think ukengineman will mind if I answer this since we collaborated on it.
The diode is the rightmost one directly under the left antenna mount screw.
I just snipped the lead off the top of the diode and then down flush with the back of the board.

Oh- You should be able to get similar scope traces by just placing your probe in the proximity of the antenna.
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