I recently acquired a piece of test equipment that was lacking on my test bench. As I work on a lot of old radios and as old radios have capacitors that are either bad or suspected to be so a decent capacitor leakage tester that operates at the voltages found in old vacuum tube equipment would be very useful to have. I’ve been wanting one for a while.
This Knight R/C tester was part of the gear retrieved from our recent trip to Medicine Hat where I picked up the RCA AR-88F. The little Knight was in quite good physical condition. Not perfect but more than good enough. The only real flaws were some marks on the front panel, as you can see in the photo below.
This is a multi-function unit. It would not only test capacitors for leakage but it is also an R/C bridge. I have a good L/C bridge and good multi-meters so those functions had no appeal to me. But a leakage tester? Now that was useful. And this one went up to 450V, which is perfect for the old radios I have.
I brought it to life and found that it worked! An excellent starting point! The 6E5 “Magic Eye” tube appeared to be in excellent working condition. In a piece of test equipment this is not surprising as it would have had very limited use on someone’s test bench. In a radio receiver that was on for many hours over many years this would not likely be the case.
The interior was clean and nothing was amiss on the top side. Of course it would need the wafer switch contacts cleaned. Nothing was missing, scorched or modified.
Knight equipment were kits made by Allied Radio. This one was well put together. Whoever did it did a very good job of it. The underside was also in very good shape. The paper capacitors would have to go, naturally.
The tubes, a 6X4 full-wave rectifier and the aforementioned 6E5 is properly called an electron ray indicator. RCA marketing called it a Magic Eye which I think is a damn stupid name but that’s what you get when you ask sales and marketing types for their opinions. Both tubes tested good on my basic little BK 606 DynaJet tube tester. Transformer voltages checked out and the power supply output voltages were good.
Meaning all this thing needed was six new capacitors and its’ wafer switches’ contacts cleaned. This was fun and easy work and once completed the little Knight RC tester worked like new!