[Bits #20] The KNIGHT Audio and RF Generator - Some History, Schematics, and Operation of the KG-650

I picked up this two-tube RF generator in an "unknown" condition because it was only $5, and because it came with a paper schematic. Having the schematic was handy, because I also bought a spare NOS 6C4 tube that turned out to be a fantastic decision. The one in the generator didn't work. The other tube in the generator worked fine. Got lucky, I guess.
I did a bit of an investigation of this generator, looking up some historical prices and advertisements, then went on to turning it on and trying it out. Two mods were made by the previous owner (could have been the original builder), and both were reasonably good mods.
The modulation output works exactly as expected, and the audio output is strong. The RF output works best in band D, but apparently the waveform is typical of these machines. The frequency accuracy of the dial is still pretty good, and that's all you need to debug an RF chain that expects modulation.
This video took just under two months to put together in my spare time. A lot of time was sunk into the intro animation. Simple looking things aren't as straightforward to get working as you'd expect. I hope to incrementally improve on this intro in later videos. For the thing I was trying to model, watch the very very end of the video. I will be very impressed if anyone can pinpoint exactly which building it's in (hint: it's in a public location with lots of foot traffic).
If you've actually taken the time to read through this entire blob of text, you should subscribe to the channel! Help me hit 1000 subscribers (284 at time of writing. Hey, it's slow going, ok? Thanks!).

[@ericnichols4987]

If you cut off the center pin of a PL-259 flush with the phenolic insulator, it fits those connectors perfectly!

[@fixitman347]

I see a future electronic engineer, here.

[@danm3188]

Nice vid overall. My $.02 you didn't ask for and probably don't want...
I did feel the Streetview of the old Allied building and extra details of finding an old catalog & value in current $ all seems like filler. Seeing the actual catalog entry was worthwhile and a nice addition though. Also, the transition to another video detailing the functioning of the generator was a bit jarring and could have done with better audio leveling. Might have been better to just mention the results, with maybe a couple screenshots, and include links in the details.
FYI, easier to just replace the old connectors with modern BNCs and more useful in the long run. Building the specialty cables seems like more work and $, plus you're left holding onto extra cables, either getting mixed in with regular or having them stored separately, all instead of just using regular BNC. They're also a better design and easier to use than the old ones. Can always hold onto the originals to reinstall them if it turns out the original parts really matter somewhere down the line, but that's not hugely likely with most of these inexpensive old kit devices.

[@Benzina124]

i have one that looks like that one. But the needle indicator is misalign with the varicap. with the varicap fully closed the need should be in a 180º angle?

[@electronicbytes5428]

I just checked, with the cap fully closed, the needle should point all the way to the left, lining up with the bottommost tick mark below 160KC. With the cap fully open, it points to the opposite end of the dial.

[@omorganstudios]

Add link to schematic...

[@raybennett8399]

What size are the connectors just got the same generator this Ray

[@danodata]

What is the tube tester that you are using?

[@dreamsaremaps]

What kind of audio output does this thing make? Or is that just a pass through? I’m a synthesizer guy and just saw one locally for cheap, wondering if it can be abused to make some noise? Sorry for the off topic question, but thanks in advance!

[@ericnichols4987]

It's a fixed 400 Hz oscillator, and a pretty decent sine wave.