Henry Radio 5K Classic Blower Modifications


Posted on Feb 5, 2014

Back cover removed showing the power supplies upper deck and the original Dayton 2C915A (220vac - 140cfm blower) mounted to the underside of the cabinet. The RF deck enclosure was removed. Upper deck of the power supply with the original blower removed. From left to right you can see the Filament transformer, HV filter cap in the rear, Bleeder resistors (back right) and the Relay/Control circuit


Henry Radio 5K Classic Blower Modifications
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transformer (front right). After a great deal of research and measuring, I chose a EBM G2E120-AR38-43 (click link for catalog - 1MB PDF file - see page 19) blower as a replacement for the Dayton. The new blower uses a split capacitor motor which is much easier to speed control by using a capacitor in series with one of the motor leads. Another advantage is the `External Rotor` design which places the motor in the center of the squirrel cage. The motor runs very cool. The EBM blower has a cast aluminum housing and zero maintenance ball-bearings in the motor. This picture shows the air switch mounted. Henry uses an air switch to turn on the tube filaments and relay power supply only when sufficient airflow is present to cool the tubes. End view showing the air vane attached to the air switch. The new blower has a much wider squirrel cage which allows it to move more air at a slower, quieter speed than the original Dayton blower. After dealing with all of the vibration problems of the original blower, I decided not to take any chances with the new one. After more research I found a company that makes small Anti-vibration Mounts ( Part # 62490-2 ) that were perfect for my application. Brad, K7ZSD, made the mounting plate for the new blower out of 3/16" aluminum plate. After further experimenting, it became obvious that an extension arm on the plate would be necessary to properly distribute the weight of the fan. Here`s a side...




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