Full restoration of my 1953 Heathkit AT1 transmitter

1953 Heathkit AT1 CW transmitter during various stages of restoration

Video link below showing the AT1 operational on 3.535Mhz at 12 watts into an MFJ-260C 50 ohm dummy load


The following pictures show the 1953 Heathkit AT1 transmitter in various stages of full restoration. Full restoration consist of full disassembling the transmitter, restoring the chassis, and reassembling the receiver with all new components. Major components such as variable capacitors, wafer switches, oscillator and band coils, meter and metal support brackets were cleaned, painted when needed, and reused. The AT1, when purchased from the seller, had a 2E26 final tube that a previous owner installed to replace the original 6L6. The 2E26 and associated circuit components were removed and the final amplifier circuit was return to its original 6L6 Final Amplifier design. The power transformer was known to be bad, it overheated quickly after power on. A new power transformer was obtained from Hayboer Transformers of Grand Haven, Michigan. Testing of the restored AT1 transmitter occurred without any problems. The transmitter was tuned into my MFJ-260C 50 ohm dummy load and indicated 12 watts output on my Heathkit IM-102 watt meter. The output signal monitored on my Kenwood TS-520S tuned to 3.525Mhz, produced a clean and stable keyed signal. Initial Final Amplifier only keying was tried and found to work. However, after careful consideration it was determined that keying both Oscillator and Final Amplifier was the best keying method. I have no desire to modify my AT1 to increase power output.

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 Front view as received        Rear view as received           Wiring view as received





Bare chassis & coil                Sanding clean up           Finished painted painting

bracket before paint prep         before painting                 Metallic Copper





New tube sockets                   Band coils mounted      New Power cord and fuse





New power transformer        Chassis wiring begins     Completed chassis wiring





All tubes in their sockets        Operational rear view        Operational front view