TCS Crystals and Crystal Socket Adapters      

         In my Hamilton TCS manual dated 14 February 1944 the crystal was listed as a CHF-40130, I am not sure which type of crystal holders are installed in the above photo but perhaps FT-249. Note that the crystal holding plate is in place and held by two thumb screws. A close up of the plate is shown below.

        Some military collectors have found that the FT-249 was utilized for the most part in the TCS.

        I found several of these MX-9 holders which are similar in size to the FT-249 buried in a box under a table at a hamfest. Obviously not for the TCS and used in a system that had the transmit and receive crystal(455 Kc IF) in one holder and utilized one socket for transmit and receive. (See Mike Morrow KK5F comments below.)

|        .155 pins, two pins- one for each crystal blank.

        A very robust crystal holder, crystals mounted on each side.
                                        EPay photo

                This might be an original TCS crystal see Mike Morrow KK5F comments below.

         Mike Morrow KK5F comments:   "The crystal unit for the TCS-series, according to the TCS-7, 9 to 12 manual Navships 900,291-1B (15 NOV 44) is the navy type-40068. That is what mine are (COL-40068). The CHF-40130 unit mentioned in your Hamilton manual must be some variant that Hamilton devised. This nt-40068 unit is not quite equivalent to the FT-249, if for no reason other than dimensional differences: - The nt-40068 HxWxD is 2.1875" x 1.375" x 0.9375", - The FT-249 HxWxD is 2.125" x 1.5625" x 1.185". The nt-40068 also has a flat side on the lower right pin...I can't tell from the photo if the FT-249 does. The photo you label "Ebay photo This might be an original TCS crystal" shows a nt-40068 TCS crystal. You can see clearly the flat side of the lower right pin.
        The Bendix MX-9E crystal shown is, as stated, a two-crystal unit. This particular example was used for channel 4 (4575 kHz) of the ten-channel AN/ARC-9. The AN/ARC-9 is the Bendix RTA-1B. Only commercial model numbers appear on the AN/ARC-9, but it was procured for nine standard USAAF frequencies, plus one channel that varied depending on if the unit is an early or late model." Mike / KK5F


        Info on the ARC-9 can be found at



         Two different holders of unknown origin are shown above. One appears to be a COL-40068.
                       Photo by Mike Morrow KK5F

                  "Attached is a close up picture of a COL-40068 crystal, marked for use in the transmitter." KK5F

        The the question why the flat pin? On the Diagram below it is labeled ground but in the TCS it is the "grid" pin.
                                         Photo and scan by Mike Morrow KK5F.               
Also, from NAVSHIPS 900,291-1B (14 NOV 44), is a figure with the mechanical details of the navy type 40068. 73, Mike / KK5F


         Possible crystal adapter? ePay photo.


         FT-243 adapter


         The adapter was fabricated out of lexan and utilizes .160 diameter wire for pins , washers were soldered on each side of the lexan to hold the wire in place and standoffs used to elevate the crystal holder.

         Not pretty but works.

         HC-6 adapter. NOTE the position of the adapter pins in the socket, each socket as two positions but only one is active..


         And old trick, I spot soldered a 20 ma bulb in series with the crystal to check for total crystal current, in this case it was very low. The crystal appears to be in the wrong position on the socket but there is a jumper underneath. Future article on crystal current in ER.

         Closer view of the 20 ma bulb and temporary solder joint.

         Practical wiring socket diagram.

        Red arrows indicate the active pins, black is ground.  Active sockets pins will indicated 60-70K to ground when selected. (Power is off)

         Note: When using crystal control on the transmitter there is NO capability to spot your crystal frequency on the receiver. I made a small modification in the power supply to allow spotting of the crystal as well as monitor the transmitter keying. See the index for this mod.


          Note: The TCS does not have a crystal calibrator, a crystal near the intended frequency of operation would be handy.


         Crystal holder clamp. Scale: four squares = 1 inch
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