Electronics Projects Index

After transitioning to WordPress, I started writing up my newer projects as ‘blog posts’ rather than ‘pages’. Please find below a list of links to every electronics project related blog post:

Comments (4)

  1. Rich Ferraro says:

    Hi Scott,
    I read with interest your mods to the kg-650, as I have recently purchased one also. I know very little about hollow state repair and nothing about solid state, and am just a hobbyist newbie at this point. I am still collecting my diagnostic equipment at this stage. I can’t find a manual for the 650, not even BAMA. They are out of print and should be public domain, but people are selling them for about $25. I was able to get the schematic from BAMA. Don’t know if you could help me with a few questions? 1)Is the filter cap the 470 MMFD? 2)When you ‘scoped the 650 via the 3 pin (12AX7, yellow trace) and 6 pin (12AT7, blue trace) would this have been done using 2 separate channels? I have a Tekronix 2246A scope but haven’t used it yet, so I’m trying to figure how to do the same test you did. And finally 3)what is a 2M pot? I’m curious if that helped with the 12AX7 being over driven, and perhaps a little more detail of the installation.

    Thanks so much for your posting this information!

    Rich Ferraro

  2. admin says:

    Hey Rich,

    The filter capacitor is a pair of 20uF capacitors with a 2.7K resistor between them. It’s marked C3 on the schematic. While these are technically two separate capacitors, old radios will often locate them in the same metal can. It’s been a while since I tore into my KG-650, but I think this was the case. Yes, I did use two channels on my scope (I have a rigol DS 1052 digital scope). “pot” stands for potentiometer, and 2M means 2 megohm (2,000,000 ohms). I haven’t modified mine with the pot, though I do plan on trying it out. Basically the idea came from the NSElabs blog post that I linked in my blog post. It seems like a good idea, though while I think it’ll correct the overdrive, it might lead to an underdrive situation in other bands.

    Unfortunately, these old tube-based RF generators can be pretty mediocre when compared to a modern solid state design. I’m currently building a solid state RF generator described in the June 2014 issue of nuts and volts, and so far it seems a lot cleaner and more versatile than the KG-650.

  3. Michael Baseman says:

    Hello,
    Do you have a copy of the KG-650 manual that you could email me?

  4. admin says:

    Hey Michael, I don’t know if I have a link to the manual, but I do have one for the schematic: http://bama.edebris.com/download/knight/kg650/knight-kit-kg650-rf-signal-generator.pdf

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