Collins R-388 Receiver s/n 1005
This receiver has a different finish from all the R-388's I've seen before. It is a satin black paint, and has properly silk-screened lettering on it. It has the "break-in" switch which was added to most of the R-388's at the factory, but the lettering at this one was stenciled. I've been told that Collins did produce some with a "plain gray" panel, not wrinkle, for special use, but this is not the "St. James Gray". I can only guess at the origin of these panel details.
I did a complete cosmetic cleanup before I started work. All electrolytic capacitors were checked for ESR (equivalent series resistance). One, C223, an 8uf @ 350v, was bad and replaced. All tubes were checked, any that were marginal were replaced. The plug-in filter cap has a date code of 9-51 on it. The PTO was 7kc out from end-to-end (in 1000kc). This was usable, but not desirable. The PTO was removed, the 2 bypass and the one feedback capacitor were replaced as preventive maintenance (the bypass checked very leaky when removed). The compensating coil had one turn removed to improve linearity and span. After reassembly it was checked and found to be only 1kc out from end-to-end, and linear within 2kc max. deviation, and no more than 1kc between adjacent 100kc points. The work sheet may be seen below. A complete alignment was performed, and a 3-wire line cord with new 250vac bypass capacitors installed. The top and bottom covers, and the 2 tools are included. The phenolic end of the capacitor tuning tool has one ear broken off, but could be reworked.
As you can tell, the pictures don't consistently represent colors, and may not show all details as they are not high resolution. It's the lighting and/or the camera's fault. I've included plenty of pix for your viewing pleasure.
here's the worksheet on the PTO work, it's kind of blurry, but the bottom line shows the final calibration at each 100kc point, the right hand end was the start point at 3000kc.
To see some of my other work on Collins equipment, with the PTO work in
click HERE and HERE and HERE
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