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Old 11th July 2019, 03:50 PM   #571
w5jag is online now w5jag  United States
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I hooked up the cheap eBay AD9850 DDS module last night.

It comes with nothing, no instructions, no pigtails, no encoder, so I had to spend a bit of time hooking that stuff up, which kept me from being able to spend much time playing with it.

I don't know what the correct voltage is, but this one is best at about 8 VDC. Below that, you get output, but can't see the display. Above that, the display will fade after a minute or so.

These are advertised as 0-55 MHz, but this one has only a 125 MHz clock chip, and the useful upper limit maxes out at about 41 MHz, or so. So, it should really be advertised as 0 - 40 Mhz.

This one has kind of an interesting feature, in that as the the encoder is spun faster, the tuning rate advances, much like a real radio. I installed a non detent encoder on this ( because it is what I had in stock ) so it has a nice feel, but for mobile use, I think a detent encoder will be a better choice.

There is an RF board on the back of the DDS board. This one has a non descript SOT-89 chip that just says "RF" on it. THe gain is set wrong for frequencies around 20 MHz, as shown in the FFT. There is a jumper that can be removed to turn the gain down in this range, but I have not played with that, yet.

FFT's attached in the 5 MHz and 23 MHz range ( low and high side injection for converting 14 MHz to 9 MHz ) and you can see that the 23 MHz signal is about ten fold stronger than the 5 Mhz side, and horribly distorted as a result. 5.X Mhz looks good, only harmonics of the fundamental show up on the FFT.
Attached Images
File Type: jpg 5 Wave.jpg (156.6 KB, 84 views)
File Type: jpg 5 FFT (1).jpg (175.9 KB, 83 views)
File Type: jpg 23 Wave.jpg (142.9 KB, 84 views)
File Type: jpg 23 FFT.jpg (163.1 KB, 83 views)
File Type: jpg IMG_20190710_201145451.jpg (194.5 KB, 81 views)
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Old 12th July 2019, 12:09 PM   #572
jackinnj is online now jackinnj  United States
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Originally Posted by Tubelab_com View Post
We haven't had that kind of standing water here, just newly formed rivers running where streets used to be. Not much of it has made even the local TV news, but there are several videos on Facebook, one with an unoccupied car being swept down the street by the water.

The creek behind our house runs from the Ohio rive,r past us, then all the way into Pennsylvania (20 miles). The sun can be shining here, but a strong storm or snow melt 10 miles to our east can flood our backyard. So far that hasn't happened in this storm series.
George - you would find McCulloughs book “Pioneers” to be very interesting - your neck of the woods from the 1770s to 1850’s.
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Old 12th July 2019, 03:59 PM   #573
w5jag is online now w5jag  United States
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Disabled the gain compensation for the 20 something MHz band.

Looks better. I'll use the RP to look at it when I get a chance.
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File Type: jpg IMG_20190711_202128185.jpg (160.9 KB, 23 views)
File Type: jpg IMG_20190711_202047966.jpg (153.9 KB, 17 views)
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Old 16th July 2019, 01:13 PM   #574
w5jag is online now w5jag  United States
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https://apolloinrealtime.org
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Old 16th July 2019, 01:19 PM   #575
gpauk is offline gpauk  Scotland
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Great link - thanks!
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Old 16th July 2019, 01:30 PM   #576
jackinnj is online now jackinnj  United States
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Interesting -- I remember going outside and just staring into the sky after this was over.

I don't think we got a color TV until 10 years afterward!
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Old 16th July 2019, 02:24 PM   #577
w5jag is online now w5jag  United States
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Unified S-band - Wikipedia

References 1 and 4 are pretty interesting reading. The command module ran a 20 watt carrier.

I recall reading that some Ham was able to pick up one of the lunar backpacks with a giant corner reflector antenna - they were in the UHF aero band - 273 something MHz, IIRC. Pretty good DX.

edit: W4EJA

Eavesdropping on Apollo 11
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Old 16th July 2019, 02:37 PM   #578
Tubelab_com is offline Tubelab_com  United States
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I don't think we got a color TV until 10 years afterward!
I had the only color TV in the neighborhood. It was a 1957 vintage Emerson (RCA built) that I had rebuilt with a 60's vintage all glass CRT. My bedroom was the old garage with some carpet (bare concrete, bare feet, and hot chassis electronics DON"T mix). There were 30 or so people stuffed into it in the middle of the night to watch that first live color broadcast from the moon.

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I recall reading that some Ham was able to pick up one of the lunar backpacks
There was an older ham who had built a large dish antenna with lunar tracking to receive the LEM to Earth transmissions. He had recorded them to analog tape and he would play them to an audience in a forum meeting at the Dayton hamfest in the early 2000's. His completely independent transcription of the events helped dispel some of the "it never happened" conspiracies. Don't know what happened to it all when he passed.
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Old 16th July 2019, 05:42 PM   #579
gpauk is offline gpauk  Scotland
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Yes, I also knew someone who also recorded a lot of the transmissions. Which ought to have dealt with the "fake news" brigade - but the always just come up with some other nonsense. You can't win!
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Old 16th July 2019, 06:12 PM   #580
gerhard is offline gerhard  Germany
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Interesting -- I remember going outside and just staring into the sky after this was over.

I don't think we got a color TV until 10 years afterward!
We in southern Germany can stare tonight, too. 2/3 Lunar eclipse.



BTW. I have not forgotten you. I have built up the first 3 pieces; the post
amplifier was oscillating. That was coupling over the analog mux, I could
fix that with isolation resistors. Expect mail early next week.

Gerhard
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