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Trawling through some old posts, I realised that a while back someone asked me to put up some pix of some of my old gear - and I completely forgot about it!
Some of this has been posted before elsewhere, so apologies to those who've already seen it, but for the rest of you......
1965 - My first reliable radio:
This Graupner/Grundig Variophon/Varioton was a "bang-bang" system, each function requiring two channels. Left rudder was one channel, right was another, and so on. Unlike American "reed" sets which used a reed bank - something like the thing you find in music boxes - to separate the "tones", the Germans (Grundig and the similar Metz system) used electronic tuned filters. These could be bought separately in two channel modules. So you would get the basic receiver module (the red one), and then plug in channel modules, each module having two channels and controlling one function.
The transmitter was also modular. Mine started out as a 4-channel (2-function) outfit with one stick. I later added the second stick unit and the module for an extra 4 channels. I only bought one extra receiver module though, and only ever used 6 channels (3 functions - rudder, elevator and throttle).
The original receiver was a super-regen type (the small one separate in the photo), which only allowed one model in the air at a time. Later I bought the superhet receiver (larger red module in the stack) so that I could fly at the same time as my clubmates!
The servos are two Bellamatic 2s (self centering for rudder and elevator) and a servo-auto-matic (non-centering, for throttle). All the servos had slipping clutches to prevent overloading the motors!
The little grey modules on top of the receiver were to speed up centering. This was a relay receiver, and when in "neutral", the servo motors were shorted out. This made them very slow to return to neutral. The grey modules plugged in betwen the receiver and the servo and allowed you to adjust the centering speed!
The receiver required a 5-cell nicad (6v) and there was a separate 2-cell nicad for the servos (2.4v). The transmitter ran off 12 volts.
It was almost totally immune to outside interference, and being all electronic - unlike the American sets - any Grundig Tx would work any Grundig Rx without re-tuning! The American "reed" sets needed lots of fine tuning to achieve reliable operation, and a receiver would only work reliably when operated by its matched transmitter!
1968 - The mighty Bonner Digimite:
The radio actually dates from late '66, but I bought it second hand off another club member. I gave about £200 for it - probably the equivalent of over £2,000 today! Certainly enough to buy a very respectable second hand car!
Each servo was the size of a packet of cigarettes, required 7 wires to connect it to the receiver, had a linear rack output and a thrust of 8 lbs! They came in two varieties - end fail-safe for the throttle, and center fail-safe for the aerodynamic controls! The servos were completely symmetrical, and reversing was achieved by removing a servo, turning it around, and replacing it!
The receiver was the size of TWO packs of cigarettes strapped together, and required a 7 cell nicad to power it! Total airborne weight, about 28 ozs (just over 1 1/2 lbs)!
Very reliable!
I even flew a Kavan Jet Ranger and a Schluter Gazelle with this, though I did use an own design receiver and more modern servos! If you look at some of the old films I posted a while back, you'll see me flying with this transmitter!
The Digimite was the first "mass-produced" digital proportional system. There had been earlier digital systems, but they were only produced in small numbers. Other proportional sets of the time were all analogue, and limited to 4 channels as a result. The Digimite was the system that broke the mold, and set the standard for all the other systems that followed.
1971 - Sprengrbook 6 channel:
This was probably the most reliable and highest regarded set of its era! It was designed by Doug Spreng, a former American National Champion, who was living in the UK for a while. Doug was credited with having invented the pulse-width tracking servo, and hence the modern digital radio system. The fact that we still use the 1 to 2 mS pulse at a 50 or 60 Hz frame rate that he invented back in the early 1960's gives you some idea of the genius of the man!
The receiver used SCSs (Silicon Controlled Switches) as the decoder, and these were a bit temperature sensitive - they didn't like working below freezing! (No integrated circuits back then!) After one failed on me one freezing winters day, I bought a bag full of them from the local electronics shop, and spent a couple of days checking each receiver with a can of freezer spray, replacing SCSs until I ended up with 2 receivers that were happy in sub-zero temperatures!
The earlier "grey" servos had discrete amplifiers, and required a center-tapped 4-cell nicad to operate. The later (red) servos used an early IC amp and no longer required a center tap. These were some of the first "3-wire" servos.
Each servo had two linear rack outputs, working in opposite directions, and were mounted in black spring clips.
I used this in my first heli - a Morley 2B - in 1974.
And finally - a pair of Ace MicroPros from the early 90's:
These are computer programmable PPM sets, with very nice metal open-gimbal sticks.
Some of you may have seen the twin-stick one, as I often use it to fly the Lark. Its fitted with one of my home-brew 459 MHz Tx modules. The single-stick one has now been fitted out for 2.4 GHz, and is awaiting test flying!
These transmitters have some unique features, that are more advanced than anything currently available from other manufacturers. For example, there is an "auto-trim" button that, when pressed, re-centres the sticks to the point at which they are currently being held! You can vary the "slew rate" at which it achieves this, and can read the values off on landing to make the settings permanent!
The mechanical trims are "swapped" from the sticks - so the "ail" and "elev" channels are on the LH stick, and the "rudd" and "mot" trims are on the RH stick. This is so you don't have to take your hand off the stick whilst you adjust the relevant trims!
They have 8 model memories and 12 available mixers, plus a serial link to connect to a PC for either more storage or to display or adjust all the settings!
Sometimes, the old ones are best! (At least, that's what I keep telling the wife.....!)
Some of this has been posted before elsewhere, so apologies to those who've already seen it, but for the rest of you......
1965 - My first reliable radio:
This Graupner/Grundig Variophon/Varioton was a "bang-bang" system, each function requiring two channels. Left rudder was one channel, right was another, and so on. Unlike American "reed" sets which used a reed bank - something like the thing you find in music boxes - to separate the "tones", the Germans (Grundig and the similar Metz system) used electronic tuned filters. These could be bought separately in two channel modules. So you would get the basic receiver module (the red one), and then plug in channel modules, each module having two channels and controlling one function.
The transmitter was also modular. Mine started out as a 4-channel (2-function) outfit with one stick. I later added the second stick unit and the module for an extra 4 channels. I only bought one extra receiver module though, and only ever used 6 channels (3 functions - rudder, elevator and throttle).
The original receiver was a super-regen type (the small one separate in the photo), which only allowed one model in the air at a time. Later I bought the superhet receiver (larger red module in the stack) so that I could fly at the same time as my clubmates!
The servos are two Bellamatic 2s (self centering for rudder and elevator) and a servo-auto-matic (non-centering, for throttle). All the servos had slipping clutches to prevent overloading the motors!
The little grey modules on top of the receiver were to speed up centering. This was a relay receiver, and when in "neutral", the servo motors were shorted out. This made them very slow to return to neutral. The grey modules plugged in betwen the receiver and the servo and allowed you to adjust the centering speed!
The receiver required a 5-cell nicad (6v) and there was a separate 2-cell nicad for the servos (2.4v). The transmitter ran off 12 volts.
It was almost totally immune to outside interference, and being all electronic - unlike the American sets - any Grundig Tx would work any Grundig Rx without re-tuning! The American "reed" sets needed lots of fine tuning to achieve reliable operation, and a receiver would only work reliably when operated by its matched transmitter!
1968 - The mighty Bonner Digimite:
The radio actually dates from late '66, but I bought it second hand off another club member. I gave about £200 for it - probably the equivalent of over £2,000 today! Certainly enough to buy a very respectable second hand car!
Each servo was the size of a packet of cigarettes, required 7 wires to connect it to the receiver, had a linear rack output and a thrust of 8 lbs! They came in two varieties - end fail-safe for the throttle, and center fail-safe for the aerodynamic controls! The servos were completely symmetrical, and reversing was achieved by removing a servo, turning it around, and replacing it!
The receiver was the size of TWO packs of cigarettes strapped together, and required a 7 cell nicad to power it! Total airborne weight, about 28 ozs (just over 1 1/2 lbs)!
Very reliable!
I even flew a Kavan Jet Ranger and a Schluter Gazelle with this, though I did use an own design receiver and more modern servos! If you look at some of the old films I posted a while back, you'll see me flying with this transmitter!
The Digimite was the first "mass-produced" digital proportional system. There had been earlier digital systems, but they were only produced in small numbers. Other proportional sets of the time were all analogue, and limited to 4 channels as a result. The Digimite was the system that broke the mold, and set the standard for all the other systems that followed.
1971 - Sprengrbook 6 channel:
This was probably the most reliable and highest regarded set of its era! It was designed by Doug Spreng, a former American National Champion, who was living in the UK for a while. Doug was credited with having invented the pulse-width tracking servo, and hence the modern digital radio system. The fact that we still use the 1 to 2 mS pulse at a 50 or 60 Hz frame rate that he invented back in the early 1960's gives you some idea of the genius of the man!
The receiver used SCSs (Silicon Controlled Switches) as the decoder, and these were a bit temperature sensitive - they didn't like working below freezing! (No integrated circuits back then!) After one failed on me one freezing winters day, I bought a bag full of them from the local electronics shop, and spent a couple of days checking each receiver with a can of freezer spray, replacing SCSs until I ended up with 2 receivers that were happy in sub-zero temperatures!
The earlier "grey" servos had discrete amplifiers, and required a center-tapped 4-cell nicad to operate. The later (red) servos used an early IC amp and no longer required a center tap. These were some of the first "3-wire" servos.
Each servo had two linear rack outputs, working in opposite directions, and were mounted in black spring clips.
I used this in my first heli - a Morley 2B - in 1974.
And finally - a pair of Ace MicroPros from the early 90's:
These are computer programmable PPM sets, with very nice metal open-gimbal sticks.
Some of you may have seen the twin-stick one, as I often use it to fly the Lark. Its fitted with one of my home-brew 459 MHz Tx modules. The single-stick one has now been fitted out for 2.4 GHz, and is awaiting test flying!
These transmitters have some unique features, that are more advanced than anything currently available from other manufacturers. For example, there is an "auto-trim" button that, when pressed, re-centres the sticks to the point at which they are currently being held! You can vary the "slew rate" at which it achieves this, and can read the values off on landing to make the settings permanent!
The mechanical trims are "swapped" from the sticks - so the "ail" and "elev" channels are on the LH stick, and the "rudd" and "mot" trims are on the RH stick. This is so you don't have to take your hand off the stick whilst you adjust the relevant trims!
They have 8 model memories and 12 available mixers, plus a serial link to connect to a PC for either more storage or to display or adjust all the settings!
Sometimes, the old ones are best! (At least, that's what I keep telling the wife.....!)
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