Power transformer for old radio for sale. Characteristics:

- High voltage: 275-0-275 40MA - Secondary Power supply: 3.15-0-3.15 1.9A - Voltage: 0-4-5-6.3 1.5A - Number of valves: 4 - Primary : 230V - Power: 43VA - Measurements: Length 7.5 cm x Height 6.3 cm x Width 7 cm - Weight: 1.3 Kg - Measurements between holes: horizontal position: 6.2 x 5.7 cm, vertical position : 5.7 x 5 cm Made in Spain, high quality copper. The price is per unit. We have more transformers of different capacities. For more information, see the photograph. Ref. 1-17051 POWER TRANSFORMER FOR RADIO DEVICES, AMPLIFIER, INSTRUMENTS, SOURCES, ETC. DESIGNED WITH VALVES The fixing system is made up of two equal frames that uniformly press the core, avoiding any type of noise produced by vibrations. In the horizontal position, you get a wide base and a low point of gravity that allows mounting in places with limited height The vertical position is frequently used in old radio sets, mainly in all PHILIPS brand ranges and similar ones. Slots in the frames allow for attachment of some components, valve sockets, voltage changes, etc. that some manufacturers used to mount.  By disassembling the corresponding frame on the connections side, the transformer can be mounted in the trans-chassis position, also common in many radio and amplifier assemblies, especially those coming from assembly kits. This type of mounting requires a longer length of screws supplied. Once assembled, the frame can be removed to have better access to the connections, or kept for greater consistency in fixing.  POWER TRANSFORMERS FOR THERMOIONIC VALVE APPARATUS. The power transformer is responsible for converting the mains voltage applied to the primary of the transformer into the different voltages required in the secondary circuits. For this reason, according to current regulations, an insulation between both of them of 4000v must be guaranteed. The input socket must be protected by a fuse that supports the total power consumed by the equipment.  For example, model 17031 has a power of 65va. Applying Ohm's law we obtain a full load current of: 65va /230v = 0.28A.  Increasing this margin by 12%, the fuse in question for a normalized current value will be 315mA-L (slow blowing). The voltages supplied by the transformer are expressed in alternating current, AC (Alternating Current) and must be converted to current. continuous, DC (Direct Current) to power the different sections of the receiving or amplifier equipment. The rectifier circuit is responsible for this function and may incorporate a valve or semiconductor diodes.  The transformers presented here incorporate a separate winding for filament heating of the rectifier valve with 4, 5 and 6.3 V sockets. These voltages cover the majority of existing rectifier valves. The AZ41 is heated with 4v, the GZ34 with 5v and the EZ81 with 6.3v as an example of three very common rectifier valves in radios and amplifiers.  The winding described for heating the rectifier valve should under no circumstances be used to power other elements, since this It is connected to high voltage, DC.  The high voltage secondary is made with two windings symmetrically joined by a central tap.  The voltage and current value are determined by the number of valves to be powered.  It is recommended to take extreme safety precautions to protect yourself from possible downloads. The tension between ends of this winding is, in the largest of the models, more than 750v...  The secondary for the rest of the filaments and dial lamps is 6.3v with a central socket and labeled 3.15-0-3.15.  The central socket is connected to ground to avoid noise. (50 Hz hums.) Only if it is not rectified with a valve, the winding intended for the 6.3v rectifier can be used for other purposes, it can be connected in series or in parallel with other filament windings, adding the intensities or tensions of both.  For example, in the 17032 model we can obtain a 6.3v and 5A winding connected in parallel or a 12.6v 2A winding if we connect them in series. To choose the most suitable transformer model for our needs, the easiest method for a specific repair is its size, since this generally determines the total power required by the device. Having the measurements of the original we will only have to choose the most approximate one among the three offered. In the specifications of each valve, we will have the voltage and intensity values of the filaments and adding the values of all the valves that the device has, we will be able to choose between those offered. Generally, the 40va model will work for fixtures with 3 or 4 lamps, the 65va series for those with 5 or 6 valves, and the 100va series for those with 8 or more. The Philips brand radio receiver model BE-331A, mounts the ECH42, EAF42, EBC41, EL41 and AZ41 valves, powered by a transformer referenced F2589 with the following windings: 280-0-280v at 60mA, 4v-1A and 6 .3v- 2.5A. total 54va. The recommended transformer to replace will be 17031 since the lower model, with the same high voltage value, 17051, is limited in current in both the high voltage and filament windings. It can be mounted in a vertical position like the original Philips brand. As the materials used in the manufacture of these transformers are of the best quality and the design complies with current regulations, the voltages are more stable, with the difference between the no-load or loaded voltage being much smaller than in the old ones, which They used finer threads and windings with many more turns, negatively affecting the resistance of the windings.  The less resistance there will be less voltage drop across them and as a consequence less heat dissipation. Taking the Philips receiver mentioned above as an example, it requires a high voltage for the rectifier of 280-0-280v at full load and the original transformer supplies 295-0-295v at no-load, dropping 15V when the load is applied. The recommended transformer, reference 17031, provides 280-0-280v in no-load and will almost not vary at full load since only 60mA will be required when it can provide 90mA. In older tube-powered devices, a lot of heat is generated, which is dissipated by the lamps themselves and the resistive components.  Proof of the goodness of the materials used in the construction and calculation of these transformers is the working temperature that does not exceed 40ºC, well below what is required by the standard that accepts up to 60º.