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Collins 32S-1 Transmitter Main Control K1 Relay Replacement
My #1 Collins 32S-1 transmitter developed a problem with the main control K1 relay. I noticed there was no RF output even after loading (Tuning) of the final amplifier. I noticed the T/R relay K2 was not energizing in any transmit mode (TUNE, LOCK, PTT, or CW). The problem turned out to be one set of the main Control Relay K1 N.O. relay contacts were not making contact in transmit. Those 2 relay contacts must connect in order for the K2 T/R relay inside the final amplifier to energize, providing an RF path to the rear “RF OUT” socket. A gentle push on the outer contact in transmit resulted in K2 T/R relay energizing. I tried bending the outer N.O. contacts (#8 contact in the pdf file link below). While that worked, it only lasted a short while, a minute or two, and those contacts reverted back to not making contact in transmit.
There are no known sources for a more modern replacement relay for K1 so the only source tht I am aware of is a used K1 relay on a 32S-1 or 32S-3 transmitter parts chassis.
Removing the K1 relay requires first removing the final amplifier enclosure. There are 5 small Phillips pan head sheet metal screws to remove the to lift the final enclosure up and off of the chassis. Be careful lifting the enclosure as 2 of the enclosure hold down tabs can get caught up in the “Load” control pulley’s metal dial cord. Take your time, pay attention, and gently remove the enclosure.
The K1 relay has 2 small Phillips head pan head machine screws with small/short hollow metal stand offs. The screws are accessed on the top of the chassis. Pay attention when removing the 2 screws as those metal hollow stand offs can fall out when the machine screws are removed from the relay frame. Once the relay is removed you should have 2 small Phillips pan head machine screws and 2 small hollow metal standoffs.
I first pulled the solder terminal insulated covers back off of the relay solder terminals and back along the harness wires. Do not discard these covers as they will be reused once the relay wires have been reconnected.
There are 13 wires to remove from the relay, 3 on the relay coil terminals plus 10 on the individual relay solder terminals. The pdf file link below outlines each individual wire, wire color, and what solder terminals the wire(s) connect to.
Using a replacement relay from a 32S-1 or 32S-3 parts chassis, use care to clear/remove all of the wire residue from the relay solder terminals and ensure each solder terminal “hole” is clear of solder.
Check each solder terminal continuity using an Ohm meter and by manually pressing and releasing the relay armature with your fingers. The relay pdf file link below shows the “Energized” (solid Black Line) and “Non-energized” (Dotted Black Line) connections. You should see continuity in each “Energized connection. To view continuity in the “non-energized” connections, you must connect your ohms meter across those 2 terminals then press the relay armature with your finger. You should see continuity. Release the armature and the continuity measurement should disappear.
Pay close attention to the wire colors when reconnecting the wires to the relay solder terminals. I’ve listed each individual wire and wire color in the relay pdf file link below. Those numbers are mine and they are not found on the transmitters manual or schematic. I included what solder terminals each wire connects to on the K1 relay. The wires are “Stranded” so ensure the wires are fully twisted so the entire Stranded wire slides through the solder terminals and is bent flat against the terminal before solder is applied. Use just enough heat and solder to make a solid connection. There should be NO Solder Blobs!!! Once all the wires have been reconnected to the replacement K1 relay, recheck your work to ensure the correct wire color is connected to the proper relay solder terminal. If all is okay, slide the old terminal covers back over each relay solder connection, making sure the covers are fully seated over the solder terminals.
While you have the final amplifier enclosure removed, I highly recommend cleaning the K2 relay contacts. Use a piece of paper wet with contact cleaner. Place the paper wet with contact cleaner between the relay contacts and gently press the K2 relay armature with you finger and slide the paper between the contacts. Repeat the process until there is no dark streaks on the paper. Perform this cleaning process on each set of contacts.
The link below outlines the K1 relay solder terminals, each solder terminal’s wire color, and an explanation of 2 sources for loss of RF output. The “second” source for loss of RF output is the reason for replacing the K1 main control relay in my 32S-1 transmitter.
The 32S-1 K1 relay replacement is completed. The replaced relay is working perfectly and the 32S-1 transmitter is back up and working properly.
