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Another 813 Build




 
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Author Topic: Another 813 Build  (Read 5773 times)
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W1RKW
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« Reply #75 on: March 17, 2019, 05:04:41 PM »

I have an enclosed rack that I acquired from Joe/WB1AIU which is the home of GORT.  The rack is 4.5ft tall and is 24 inches deep. I mounted it on heavy duty wheels. Between the rack and the hardware installed in it, it's about 250lbs. It has 19" rails both in the front and in the rear.  I took advantage of of the rear rails by installing perforated angle iron between the front and rear to be used as sliders for the 4 chassis support sections of the transmitter. There are 2 chassis's with transformers and there is no way that the front panel of each chassis will support itself let alone trying to install and remove those chassis's by removing and installing the mounting screws. That would take to people.   The rails provide support and unstress the front panel and I  am able to remove/install each chassis by myself.  
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Bob
W1RKW
Home of GORT. A buddy of mine named the 813 rig GORT.
His fear was when I turned it on for the first time life on earth would come to a stand still.
w8khk
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This ham got his ticket the old fashioned way.


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« Reply #76 on: March 18, 2019, 08:03:21 AM »


I have a question for the group related to the screen clamper, etc.  

**Update:  Never mind - question answered offline.

T

Tom, after thinking about your question and because I did not arrive at any valid hypothesis on my own, I refrained from commenting prematurely.  But I (and possibly others) would  like to hear what you learned offline about the behavior of the screen grid voltage and current when using the combination of fixed and grid-leak bias as the grid current changes.  (I was out of town for a few days, hence the delay in my comment.)

Thanks in advance for taking the time to elaborate!
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Rick / W8KHK  ex WB2HKX, WB4GNR
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"Let's go sailing, Tommy!" - Yaz


« Reply #77 on: March 18, 2019, 08:37:17 PM »

Hi Rick,

Actually I wasn't really satisfied with the answer I received and didn't want to waste any more time on it.  I decided the next time I fire up the 4X1 rig I will see for myself exactly how the screen current responds to grid drive as the grid leak bias increases.  It eventually settles at 280 mA with full grid drive and with the Variac-driven screen voltage adjusted right, but the path it takes to get there, I don't remember... :-)

T
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Frank / WA1GFZ says when he's working near high voltage, as a warning he sings this song by Jay and the Americans: "Come a little bit closer, you're my kind of man, so big and so strong, come a little bit closer, I'm all alone and the night is so long."
w8khk
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« Reply #78 on: March 18, 2019, 09:31:56 PM »

Thanks for the explanation, Tom. 
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Rick / W8KHK  ex WB2HKX, WB4GNR
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