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Class E Transmitter Progress




 
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Author Topic: Class E Transmitter Progress  (Read 1046 times)
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ka1tdq
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« on: March 06, 2021, 10:40:22 AM »

Boy, have I been busy! It's been a while but progress does continue with the 8-FET transmitter. I decided to make a series of YouTube videos as I go along. It's not really a tutorial - Steve's website has all the detailed instructions, which I do cite. But, there are literally no YouTube videos out there to sort of chronicle building one of these beasts, so here's my stab.

Video 1: Intro to the project and talk about the phase splitter / duty cycle adjust board

https://youtu.be/j4F0KA-qlE8

Video 2: Demonstration of the phase splitter and talk about next video for crystal oscillator as signal source

https://www.youtube.com/watch?v=SpoEd438Xsg


Jon
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K4QE
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« Reply #1 on: March 06, 2021, 07:18:42 PM »

Nice work, Jon!  Looking forward to the upcoming videos.

73, Tony
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73, Tony K4QE
AG5UM
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« Reply #2 on: March 06, 2021, 07:30:36 PM »

Great idea Jon, to chronicle the build with videos, I enjoyed the videos, looking forward to following along with your build. Good job. Keep up the good work.
Donnie/AG5UM
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wb6kwt
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« Reply #3 on: March 07, 2021, 08:32:37 AM »

Thanks Jon, nicely done. Your camera person is doing a great job also.


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ka1tdq
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« Reply #4 on: March 07, 2021, 11:45:12 AM »

Thanks all! There aren't many builders doing class E stuff in America. I'm guessing 20 people. I enjoy this sort of thing and may be the only current project out there. Sit back and I'll try to keep you entertained.

Kuddos to my wife with camera duties.

Jon
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ka1tdq
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« Reply #5 on: March 07, 2021, 11:45:47 PM »

I am actually almost finished with the oscillator for the 3rd video. It's shown in two pictures attached to the first module. Come to find out, 7740 KHz crystals are common enough on eBay and are twice the frequency for 3870 KHz. I'm waiting on the remaining parts to arrive to finish.

The first picture shows the stand I built for the transmitter itself. I welded up a mount beneath the transmitter that'll hold 4 meters (IXDD bus voltage, drain voltage, Iphase1 and Iphase2). The cabinet on the left will hold the power supply and analog modulator. On top is my antenna tuner with all components mounted at 90 degrees from each other.

Jon


* IMG_0454.jpg (1325.94 KB, 2016x1512 - viewed 76 times.)

* IMG_0452.jpg (1079.79 KB, 2016x1512 - viewed 87 times.)

* IMG_0453.jpg (1029.04 KB, 2016x1512 - viewed 85 times.)
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ka1tdq
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« Reply #6 on: March 11, 2021, 10:31:39 PM »

I finished the oscillator plug-in module and it works correctly with the phase splitter. The first photo shows one of the output square waves along with the clock input. The second picture shows both output square waves.

I'll post video when my wife has a chance to record it.

Jon


* IMG_0462.jpg (1425.95 KB, 2016x1512 - viewed 70 times.)

* IMG_0463.jpg (1368.15 KB, 2016x1512 - viewed 75 times.)
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ka1tdq
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« Reply #7 on: March 13, 2021, 01:17:25 AM »

Here's the third video in the series:

https://youtu.be/iWRlX0hVlrw

Jon
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ka1tdq
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« Reply #8 on: April 03, 2021, 10:32:04 PM »

Here's where things stand now and the 4th video is coming. I've changed the design a little bit on the modulator shelf to also incorporate a negative peak alarm, a negative peak keep-alive circuit, and a pre-modulator overcurrent trip. I was trying to come up with ways to trip on overcurrent but they all weren't very practical. So, I ended up borrowing from Steve's a little bit, but simplifying it for my application. Sorry Steve, but you WAY over complicate things. Aside from the RF deck stuff. That's pretty much how it has to be.

Some parts from DigiKey for the overcurrent trip are on backorder and I want to finish that before I do the video.

Until then, keep busy, partake in some indulgences, and keep the BS below a 7.

Tootles!

Jon


* Modulator and Power Supply.jpg (1740.83 KB, 2015x1511 - viewed 34 times.)

* Overcurrent Trip.jpg (2209.04 KB, 4031x3023 - viewed 39 times.)
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ka1tdq
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« Reply #9 on: April 11, 2021, 10:11:30 AM »

Getting ready to assemble the analog modulator. Here's the layout. My finger is pointing to the simplified overcurrent trip circuit. The power supply is all done.

I'm going to try using epitaxial diodes in the negative peak limiter. They'll be stacked for easy mounting as shown with a TO-220 style resistor on top.

I'll shoot the video after my wife gets back from Vegas this week.

Jon


* IMG_0659.jpg (3105.41 KB, 4032x3024 - viewed 17 times.)
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