[MRCA] BC-654/SCR-284 project 2.1 power supply

[Ray Fantini]

I received some shiny new VBP-1 solid state inverter last week and set about solid stating the power supply packs for the BC-654/SCR-284 radios. Have a total of four PE-104 to convert, two of them were NOS having never been used. Had a box full of vibrators with only one that worked. With the exception of one power supply, they all had bad dry filament rectifiers (4A1) so all of them got new full wave bridges that are installed in the same location as the old dry rectifier. The new bridge is wedged in there with no mechanical attachment.  With using the new VBP-1 replacements I had to install a couple diodes (NTE-125) to be the new bias and B+ rectifiers being this was done mechanically by the old vibrator. A lot of others who did this want to put it on the same plug as the solid-state replacement but I think it works just as well to install them on the vibrator socket. You can see all this in the attached picture. And I also changed the contact side of 4C1 that appeared to be a hash bypass capacitor acrost 4T being did not expect any hash from the diode.
For installing the VBP-1 assembly I cut open a bunch of vibrators keeping a one-inch skirt on the socket to facilitate installation and removal. You only need three wires with the VBP-1 and the card itself is about the size of a postage stamp so using twenty-two-gauge wire that supports the assembly so it can sit right in the center of the housing.
Everything runs great so far, the VBP generates no heat and appears to be quiet where the old mechanical vibrator did interduce some vibration into the frame.
Interesting thing about chopping open vibrators, couple of them were NOS and all reviled corroded contacts. The internal padding was soft and removable on some but on the others the internal padding had appeared to melt all over the assembly. Have no idea why.

Ray F/KA3EKH

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