Heathkit AO-1 Audio Oscillator w DC Offset Switch, Probe & Manual – Serviced, Tested & Calibrated

This Heathkit AO-1 Audio Oscillator with a DC Offset Switch has been serviced, tested and calibrated by Steve McKinley of Atlanta Tube Amp and it's ready to go! It comes with a probe, spec sheet and schematic.

As part of its service, the power supply multi-capacitor can has been replaced/upgraded as well as the coupling capacitors. In addition, all the ½ watt carbon composition plate load resistors were replaced with one-watt metal oxide ones for greater consistency, tighter tolerance and better heat absorption. All other resistors were checked and replaced if out of spec. Also, the DPDT Sine Square wave switch was replaced as the original one was broken.

It was calibrated at modern voltage (122VAC) to give the most pure and stable sine and square waves.

In sine wave mode, there will always be some DC at the output in this design due to the NFB applied from the output back to the cathode of the AF amplifier stage. Therefore, the voltage at the cathode of this stage will appear at the top of the 50K output level control, producing a DC component in the output. As DC can sometimes be useful, a DC Offset Switch was installed to be able to turn the DC output on or off.

Spec sheet, schematic and ¼” probe included.

Why would you get this one? You might be able to can get a HP or Wavetek for less but it will have all the age related servicing issues and needs (ex. unwanted distortion, worn out and broken parts, etc.).

This is NOT one of those “untested, estate sale, my uncle was a TV repairman and he used to use it” audio oscillators.

With its service, testing and calibration, this Heathkit AO-1 Audio Oscillator is a winner and is ready to go!

Get it before someone else does.

Packed, insured and shipped via UPS.

Tektronix oscilloscope not included.