Geoff_H

Just a reminder, do not remove oxide from electrical contract surfaces with carborundum (emery) it attaches small quantities to the surface and will oxidise with electrical current.

In the 1970's when we first used computers in industry for control we would get many failures, almost always on computer board connections, we would always carry an ink rubber to remove oxides, more often happening in we weather. We were told by plug manufacturers that 30,000 psi connection pressure was needed to prevent high resistance connections. I believe that earth connections should be checked regularly, particularly after a wet period like the east coast is experiencing

I think that you maybe right. Is there a difference between the shield and the ground plane. My experience is with instruments.

It should have the shield wired to an instrument bus via a dedicated connection. However the installer may have connection the shied to earth at the aerial. The thing to do is only earth one shield end.

Brendan the shield is best earthed at the tx/rx module. The antenna end shield is best isolated from the chassis of the aircraft. If the shield is earthed at both ends you will get an earth loop current in the shield, this loop current will radiate inside the aircraft and interfere with most devices. It is also recommended to check that an accidental earth is not happening at the antenna and a solid earth exists at the rx/tx module.

Check your cable shields for earthing. Must be earthed solidly, and most importantly at one end only.

Not totally sure but I expect that it has to do with the on/off control circuit. The battery is one huge Capacitor. I expect that the others have a amperage demand circuit and use that to control. I think that the Capacitor one uses a simpler control circuit using the Capacitor and the resistance of the cables to the battery in an RC delay circuit that would give the frequency of the on/off operation. Why the control doesn't have an inbuilt Capacitor is don't know, but I am guessing it is to do with the size of the box

I expect that the Capacitor is to give the MOSFET a voltage level at which to switch off. When the Capacitor discharges into the aircraft electrical system iits voltage will start to drop, the control circuit will see this and turn the MOSFET on. When the Capacitor reaches the voltage of the set voltage for aircraft operation the control system will turn the MOSFET off. This cycle continues as required.

Another technique is the same as inverter technology. It uses switching using Mosfets. If you use resistance for control a large amount of heat will be produced. In essence the .Mosfet will switch on and when the output reaches the desired voltage the Mosfet will switch off. It does this as often as the time for the outlet voltage to drop to a predetermined value. On and off will be very quick at low power and very long at high voltage. Efficiency low at low power settings.

Second sentence should read: The non permanent magnet alternator/ generators regulate the magnetic field strength of the rotating field to give a stator voltage of 12volt

Not exactly the same. The non permanent magnet alternator/generators alternator the magnetic current of the rotating field. The stator voltage is then a function of rotating flux density and velocity. The relay was altering the field current. With a permanent magnet rotor the field flux is fixed, the velocity varies so the output voltage varies with rpm, so you have to convert the output voltage to 14volts (or 28volts depending on system). It is just the same as a phone charger that converts 110 or 240volts to 5/12volts automatically.

Doesn't it depend upon whether the output from the alternator is below or above 14V?. I think that you are right but if you use straight resistance you may have a heat dissipation problem. Yes I agree that the oscillation frequency is high, that way only a small transformer is needed. In the 1970's I had a job that needed 5volts from a 24Volt supply. Two racks of many 2n3055's tied together, then switch mode became available, one small package 1/10 the panel space and no heat issues.

If I understand it correctly the way a permanent magnet generator works is the same as a switch mode power supply. The AC voltage from the generator that will be speed dependent. This voltage is rectified and a large capacitor charged. A control circuit will turn a power transistor on and off through a transformer at a rate that will give an output at the aircraft system charging voltage the rectify this ac voltage and connect the rectified output to the system. Well in a similar way to this.

I was thinking about buying an 80% complete Starlet, this would be like buying an advanced kit phone. Only 80% to go lol. So I looked at what needed to be purchased, cowling, fabric props fuel system radios paint, the 80% to go looked good. Then I priced these components, including freight, it would be cheaper to buy an already flying one.

I have a Chinese lathe. A dead copy of an American lathe. However it needed adjusting of the lathe from new. The Chinese However did not know the material composition of the critical parts. A high tensile steel part was copied as mild steel, the zero backlash devise is now useless. Sorry I don't share your acceptance of the Chinese propaganda that they can make good things. Look at their NPT threads are NP no T.