Cubic Communications CDR-3250 VLF-HF Communications Receiver Fan Noise Solution Part II
Cubic Communications CDR-3250 VLF-HF Communications Receiver Fan Noise Solution Part II
This post will furnish additional detail about installing a quieter and more efficient rear panel fan in the Cubic Communications CDR-3250 VLF-HF Communications Receiver.
As I mentioned in the previous post, the duct/standoff/adapter can be made from wood. I chose solid pine because I had some in my offcuts box; plywood would be a good choice too.
The dimensions of the duct are: 75mm H x 60mm W x 15mm D as shown:
The holes are 55mm diameter (fan side) and 45mm diameter (receiver grille side). The hole on the receiver side had to be smaller in order to accommodate the 42mm bolt hole pattern of the OEM fan, while leaving enough material around the fastener holes for a sound mechanical joint. In addition, I happened to have 45mm and 55mm hole saws available.
I drilled appropriate pilot holes in the wood to accommodate countersunk head wood screws on the receiver side, and used a small amount of wood glue in each pilot hole (just prior to attaching the duct) to act as thread-locker. The duct was notched on the fan side to accommodate the power wires. The wires were routed through the notch in the duct and through the grille and then plugged into the OEM plug as follows:
Both of my 3250’s have been retrofitted with quiet fans, and the result is a dramatic reduction in background noise in my radio room. Finally, as the CDR-3280 is a desktop version of the the 3250, the retrofit should apply to the 3280 as well.
Shaun Merrigan
