I suppose I left the cake dangling in the pervious blog post by not posting any oscilloscope screenshots. Worry not, they are included in this post!
Before powering up the unit I tested the transformers insulation resistance with at 1 kV. My insulation tester did not measure any leakage current, so I felt confident I could power this unit up.
Now comes the challenge of applying mains power. I certainly don’t have a matching power cord for the power inlet on this function generator. I didn’t want to use alligator clips, because the contacts are exposed and if they were to fall off you have live contacts dangling around. I opted to try some shrouded crimp connectors.
Trying to increase the diameter of a butt crimp connector to mate to the power pins worked okay I suppose. Using a spade crimp connector was a far superior solution. I had to form the rolled contact ears(?) back just a touch in order for the connector to mate over a power pin. As a bonus, the connector shroud maintains a friction fit when mated to a power pin.
This worked well for a short-term test. Eventually a new power inlet connector will be needed.
I slowly brought up the line power to the unit with my variac auto-transformer. No smoke, only sine waves!
I bought this unit off ebay not being totally sure if it would function. However, I am just delighted that the function generator indeed does work!
The amplitude adjustment potentiometer is very scratchy and will likely need to be replaced:
Probing the BK3010’s output with a 10x Scope probe shows the unloaded response of the function generator:
As received, the THD of the sine output at 1 kHz was – 38 dB. This is just slightly worse than the datasheets 1 % THD specification for a sine output for frequencies less than 100 kHz. Granted, I may have bumped some of the trim pots when I was taking photographs, so it may have arrived in spec. After adjusting the VCO’s high-side current source for a 50 % dutycycle, I picked up 6 dB in sine THD. After adjusting the sine-shaper distortion pots 1&2 I was getting THD figures in the -50 dB range and below.
All in all, its a really nice keepsake instrument . With a little more TLC, these could be a daily use instrument too! (The switch contacts need some serious cleaning).
The BK3010 also got a chance to say hi to the new kid on the block, the MP750668
Thanks! I am having a blast taking a look at this instrument 🙂 The 182A looks really nice too! I like how the power indicator light, also lights up the frequency adjustment marker.