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Knight T-150 Rebuild

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Author Topic: Knight T-150 Rebuild  (Read 631 times)
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« on: May 31, 2019, 08:34:35 PM »


   I have begun reworking a Knight T-150. I'm about to take out the transformer and test it while repainting the cabinet and cleaning up the chassis. At this stage of the game I want to ask about the transformer and the chassis.

   As for the transformer - it looks good from the top and bottom. The sides that show the lamination of all the steel plates has some rust. Looks like surface rust to me. My instinct is to hit it with a wire brush and then give it some sort of clear coating to prevent future rust. Here's the question: Is there anything negative that could result from doing this? (trapping heat, sealing moisture inside?Huh other things I haven't experienced yet??)

   As for the chassis, I think (reckon) its some sort of simple steel sheet metal with a flat silver paint on it. Did they plate it with anything? The front panel has a big warp on one side and needs to be flattened - any tips on how to do this?

    Any help appreciated, Thanks, Bruce (N3RIK)

   Addendum follows:
                .........Thanks for all the responses.  I just attached 3 pictures of the project


* knight t-150.jpg (1555.58 KB, 3041x2373 - viewed 62 times.)

* knight t-150 mk2.jpg (1626.13 KB, 2901x2754 - viewed 47 times.)

* knight-t150 mk 3.jpg (1020.69 KB, 2083x2382 - viewed 59 times.)
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« Reply #1 on: June 01, 2019, 02:01:55 AM »

this may be worth reading - spectral purity problems
AC0OB - A Place where Thermionic Emitters Rule!
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« Reply #2 on: June 02, 2019, 01:20:01 PM »

My experience with the T-150 is it has a robust power transformer compared to some of the earlier HeathKit transformers.

Some surface rust on the exposed laminations is no big deal. I would brush it very lightly and paint it flat black for max heat dissipation.

The main chassis is steel but with what coating I do not know. The front panel on mine is brushed aluminum.

As Rod mentioned, there were some problems with the VFO but they can be mitigated with some component changes as shown in the .pdf file.

I only put tube shields (painted flat black as well) on the 12BY7A and the 12AX7A.


Phil - AC0OB

* Knight T-150 AC0OB Modifications Schematics.pdf (833.61 KB - downloaded 41 times.)

"What kind of Koolaid do they make you drink in the Physics Department?" Charlie Epps to Dr. Larry Fleinhardt, NUMB3RS   Smiley

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Your best isn't as good as you can be.

« Reply #3 on: June 02, 2019, 02:17:37 PM »


If you replace the 6DR7 with a 6EW7 you may want to look for one of the "fat bottle" versions.


* 6EW7 fat slim.png (303.64 KB, 485x568 - viewed 57 times.)

Fate does not protect its worshipers any more than its deniers.

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« Reply #4 on: June 03, 2019, 12:03:53 AM »

I had a T-150A I built as my first rig in 1964.
Upon power-up, the diode connected to ground in the HV voltage doubler power supply shorted.
(Bang!) A friend had the same problem a month later with his T-150A.  If I recall correctly, Knight
only used two diodes in that supply.  They had great faith in the diode manufacture's specs,
I suppose.  A wire-wound resistor released its sand, but the transformer survived.

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