Collins Collection
75S-1 Receiver
My 1959 75S-1 serial number 1036. Bought it on eBay.
The S meter zero pot (250 ohm) was found to be toast. I replace it with a NOS 200 ohm pot and changed the series resistor from 68 ohms to 100 ohms, 18 ohms shy of the original circuit series resistance.
I replaced V7, 6AT6 which is the Detector, AGC Rectifier, and first audio amp. This brought the receiver to life.
I adjusted the meter zero pot and the RF Level pot. I calibrated the 100Khz calibrator using 15Mhz WWV as stated in the 75S-1 manual.
I believe the CW filter is the 250Hz filter as it is quite narrow.
Excluding the Rejection Tuning not working, the receiver is performing very well on AM, LSB, USB, and CW on all bands. Video link below to see the receiver on 40 meters at night. The antenna is a 40 meter dipole up about 28 feet.
32S-1 Transmitter Serial Number 292
I picked this 32S-1 up on eBay. It appears to be in very good physical condition. There’s some dirt/dust on the chassis that needs to be cleaned up.
The P.A. Tuning shaft coupler set screw was loose causing the P.A. control to rotate 360. Tightened the set screw fixed that problem.
The EXCITER TUNING rotated but the slugs didn’t rise completely out of or back into the coil forms. I had this same problem with the above 75S-1 receiver. The rollers on both ends of the tuning assembly and the front ball bearings needed lubrication. I applied a small amount of “KROIL” using a cotton swab to the front and back rollers and to the front ball bearings. This fixed the EXCITER TUNING.
I haven’t powered up the transmitter yet. I want to give it a thorough visual inspection then perform some resistance checks first. If all goes well then I’ll power up the transmitter into a 50 ohm dummy load.
312B-4 Console
I picked this 312B-4 Console up on eBay. The paint is horrible. The cabinet paint before paint stripping.
All internal components and front panel have been removed and safely stored.
The 312B-4 Console cabinet after stripping the Gray paint using Citristrip paint remover then sanded preparation for painting. The inside Flat Black has been repainted.
516F-2 Power Supply
I bought this 516F-2 power supply from a ham in Texas. It’s all original and in excellent physical condition. I plan on replacing all of the electrolytic capacitors to bring it up to modern specs. It needs a bottom cover plate.
I originally thought of using a Heathkit HP-23A power supply but after reading what needed to be done to the HP-23A supply I decided it was best to go with the Collins 516F-2 supply as it’s designed to power the 32S-1 transmitter.
