ATU rebuild

AM Radio discussion. Directional arrays are FUN!
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Deep Thought
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Re: ATU rebuild

Post by Deep Thought » Thu Nov 08, 2018 8:24 pm

I'll accept either a whine or a beg. No need to go overboard. :mrgreen:

If you give me a description of the tower and what is on it, I can model it and get pretty close to the right phase shift for optimum bandwidth without having to do a full sweep.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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Dale H. Cook
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Re: ATU rebuild

Post by Dale H. Cook » Fri Nov 09, 2018 6:43 am

Deep Thought wrote:
Thu Nov 08, 2018 8:24 pm
... I can model it and get pretty close to the right phase shift for optimum bandwidth without having to do a full sweep.
Deep has significantly better software tools than the rest of us. I can only do that the old fashioned way, with a bridge and a Smith chart. :wink:
Dale H. Cook, Contract Engineer, Roanoke/Lynchburg, VA
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grich
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Re: ATU rebuild

Post by grich » Mon Nov 12, 2018 12:04 am

Deep Thought wrote:
Thu Nov 08, 2018 8:24 pm
I'll accept either a whine or a beg. No need to go overboard. :mrgreen:

If you give me a description of the tower and what is on it, I can model it and get pretty close to the right phase shift for optimum bandwidth without having to do a full sweep.
Thank you...I won't whine because my wife HATES whining. My kneepads are on standby in case groveling is needed. :lol:

According to the 1991 license, radiator is 67m tall (122.4 deg at 1520kHz), 24" face angle-iron tower. Resistance 425 ohms, 1.53 amps antenna current for 1kw output. Nothing else on it now except tower lights fed by SO cord and a newer Kintronics 3-section lighting choke.

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Deep Thought
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Re: ATU rebuild

Post by Deep Thought » Mon Nov 12, 2018 8:30 am

What is the transmission line length? I can take that into account when adjusting the network for best bandwidth at the transmitter end.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

grich
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Re: ATU rebuild

Post by grich » Mon Nov 12, 2018 10:57 am

325 feet of 7/8" foam

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Deep Thought
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Re: ATU rebuild

Post by Deep Thought » Mon Nov 12, 2018 2:37 pm

Here you go. I ran it twice, once with a base impedance close to what the measured data shows and once with the theoretical base impedance. You can match either with the same components. The current ratings need to be multiplied by 1.6 and the voltage ratings need to be multiplied by 6.0 to account for peak modulation and safety factors.

Let me know if you have any questions or need anything else. Good luck!
Attachments
test1.pdf
ATU Design
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Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

grich
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Re: ATU rebuild

Post by grich » Tue Nov 13, 2018 12:16 am

Thanks, Deep!

I'll be picking away at this project over the winter in between other problems, but I'll let you all know how it goes.

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