Citizenship APT Instructions
 

Here are scans of the instructions that came with the radio.

Kenny,
If you only want to do a bench check or run a demo at a club meeting, a single 4 cell pack will suffice. The battery will need to have a decent amount of charge in it so the drain by the servo motors aren't noticeably affecting the reference voltage. Otherwise the servos may not run as smoothly as they should. Here's a sketch of the plug wiring.
Tom

http://www.rcuniverse.com/forum/atta...mentid=2107795

Tom,

Thanks for this bit of information. I am assuming that the separate battery packs are used so that the receiver will have a more stable voltage - is that correct?

Kenny

Kenny,
Actually, it's also for (perhaps more so) a section of the servo amp circuitry that wants a stable voltage. As the instructions tell you, using a common battery for the receiver and servo reference (while using another battery to run the servo motors) is "acceptable". Reason is because they both draw very low current (relative to the servo motors) therefore allowing the battery's voltage to have no noticeable instantaneous drop. That also explains why Citizen-Ship says you can use a lower capacity battery for these (the Rx & servo ref). A servo motor under a heavy load will draw a relatively high current and will bring the battery's voltage down, at least while the load is present and especially if the battery's charge state is on the low end. Remember we're talking about relatively small batteries here - not your 12 volt car battery that has tons of amp-hours. Also remember that when the Citizen-Ship analog radio was introduced, ni-cad battery cells were were still a relatively new item and not the higher capacity, more reliable cells used by RC'ers today.

Anyway, that's my theory / explanation and perhaps someone may want to elaborate and explain why the old servo needs the reference voltage. But don't let any of this scare you away from using a common battery pack to test out you radio. Even if the pack is run down while operating the radio, it won't harm the circuitry. Might not be good for your airplane if your flying it, however! I've used the one pack method to test both my 3 and 5 channel Citizen-Ship analogs.

Tom

The "analog" proportional Citizenship radio were really just fast pulse proportional systems with analog servos. Which is why only three functions were controlled, though a fourth servo could be added to add the CAR function (coupled aileron rudder). There are several interesting circuits and concepts with the C-S AP sets, but the were not on the market very long before cheap digital systems took the segment.

Most analog systems were closer to reed sets, since they encoded information with a frequency shift and used a frequency discriminator to provide an analog signal to the servos. Limitations of bandwidth, and inter-modulation between control tones also pushed some analog systems into a time sharing scheme to add additional control functions.

HighPlains is correct. There is no 5 channel Citizen-Ship analog, only the 3 channel. Must have thinking about the digital version, and the 8 pin Deans power connector wiring is different for it.

Tom

There were two versions of the C-S AP system. The dual stick which was the first to market, and the two axis single stick about 6 or 8 months later. The same stick assembly was then used in the early DP-5 radios.

The point of my previous post is about the encoding scheme for their so-called analog radio. In effect it was really an extension of a galloping ghost (pulse proportional) radio, operating at a much higher pulse rate. Changing the throttle was with the RF either full on, or full off to move the throttle to high or low, with changes in pulse width for rudder and pulse rate for elevator. While the throttle was moving, I believe that the other two servos tended to move back to their fail safe position (to neutral). When C-S came out with their GG system later (NPT for nervous proportional transmitter), all they had to do was change the pulse rates down to match up with the Rands systems. At any rate, it was a clever way to avoid having to build frequency discriminators ( a device that turns a change in frequency into a change in voltage) with the usual heavy toroids in other true analog designs.

The pulsed RF was also modulated with a tone at about 3700 Hz, which helped prevent CB activity from shooting you down (most voice information over a phone line is under 3000 Hz. It's also why it can be difficult to tell the voices apart of siblings, because all the higher harmonics are gone.). Anyway I think the filter is constructed from the transformer in the receiver after the signal is demodulated.

While the included schematics showed two sets of batteries, there were some circuits around for using a single set with the addition of noise suppression components. The receiver may not have been very good in this design, or may have been designed to ignore all but strong signals, since they recommend a vertical whip for the airborne radio. But if you flew upwind, the plane should get close enough to regain control if it went into fail-safe.

All in all, an interesting design in the development of modern RC systems.

When I first acquired this system, I powered it up to see if it worked (it did). I listened to the signal on a communications receiver and remember thinking that it sounded very much like a galloping-ghost transmitter. I removed all of the batteries to prevent damage from leakage and it's been in storage for about 25 years. My intent was to install it and fly it... some day. I'm wondering if it would really be reliable or if I would be risking destroying &/or losing an airplane, engine and flight pack. I would be flying in a fairly remote rural setting, so I don't believe interference would be a big concern.

Before risking a plane with it, it should have a good going over by a skilled technician.
Jaymen (Jay Mendoza) has a lot of experience with that sort of thing. You might try him.

It would be interesting to see one fly. I was thinking about if I could remember any models flown by one in any of the old magazines. There was one in Flying Models that listed the C-S AP radio called the Sea Horse, but while plans were shown, no pictures of a finished model was shown. I think it was a Don McGovern design, most likely designed and drawn up to provide filler for the magazine that he was the editor for. Pretty sure he did this more than once.

I think there was also a system test flown and discussed in an issue or two of Grid Leaks. Seems to me that they were flying either an H-Ray or a S-Ray as the test ship with a .19 for power. With fail safe, an well trimmed out H-Ray doesn't really need a functioning radio to fly successfully.

I bought a single stick version about five years ago. I don't think it was ever flown. This is from a period of time where radios dropped quickly in price (by half) and digital systems simply blew everything else out of the market.

When I was learning to fly back in the early '70s, the man that was helping me had a C-S AP system that he flew regularly, not sure what model it was in, possibly an H-ray or a Tri-Squire. As I recall, he had pretty good luck with it.

Back in the 60's I bought one of the Citizen-Ship two stick APT systems. It was my first proportional set. It was not a very good quality set. The servos were as slow as reed servos. The servo cases were made of a soft grade of aluminum and bent in anything other than a perfect landing. The servo output arm bearings were a slot cut into the servo case so you spent a lot of time straightening the cases. The engine control stick was a switch like those in a reed system. Engine control was not proportional, rather, it was blipped back and forth like a reed system. The radio link was good. The problems were mostly mechanical. I was finally able to buy an F&M proportional and get away from the two stick setup with elevator on the right side and aileron on the left. Having ail and elev on the same stick was lots easier to fly and the servo mechanicals were far better.
Jamesf

The two-stick layout is an advantage for me - I fly mode-1. As for the other shortcomings, I'll be flying an old, slow, nostalgic floater, just to show the youngsters how it was back in the olden days...

Well.. this should get a lot of hits! LOL! But they probably round up to whole numbers!

I recently found a Citizen-Ship APT single stick, and did find very incomplete schematics on vintage RC Files for the APR receiver/decoder. Does anyone still have a APR and/or servos? I'd be interested in a possible purchase, but would gladly pay shipping both ways, to borrow a set, just to document the components. I suspect in this case, the tx will end up having the rates reduced, (or a new encoder) to be used with standard GG equipment.
If you know someone who has this gear, please let me know! Many thanks! Jerry