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Old 16th July 2019, 06:33 PM   #581
Tubelab_com is online now Tubelab_com  United States
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Which ought to have dealt with the "fake news" brigade - but the always just come up with some other nonsense. You can't win!
My own daughter sort of believed that the lunar stuff was faked. I had a discussion with her that involved explaining the technology available in the 60's and early 70's......the clincher, We watched one of the original Star Trek episodes. I explained that this was the best than Hollywood had to offer at the time, and would ANYBODY possibly believe that it was real? Yes Hollywood could create a convincing fake today.....not so easy in 1970.

It took some convincing to tell her that I was talking to a man in space on my ham radio setup too. "How do you know that he is really in space?" UH, a few of us at work built the walkie talkie that he had duck taped to the window in the Space Shuttle.

The first one was a hacked Motorola MX300 on 2 meters. There was an unpublished frequency that the astronauts used to talk to the Motorola Amateur Radio Club. The project was known as SAREX...Shuttle Amateur Radio Experiment. There were unpublished radios in space going back to the Skylab days. I think the club built an HT-220 for one of those, but I wasn't a MARC member at the time.

The first few missions flew under rather low publicity since nobody knew if it would work and if it would interfere with any onboard equipment. Early on the radio's power output was rather low, under 1 watt. In the later days there were so many people calling the shuttle at the same time on the same frequency, that they just heard noise.....like a CB set in the mid 70's.
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Old 17th July 2019, 04:26 AM   #582
benb is offline benb  United States
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Originally Posted by Tubelab_com View Post
In the later days there were so many people calling the shuttle at the same time on the same frequency, that they just heard noise.....like a CB set in the mid 70's.
Now that's a pileup!
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Old 17th July 2019, 05:57 AM   #583
Kay Pirinha is offline Kay Pirinha  Germany
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Originally Posted by Tubelab_com View Post
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.

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.

It wasn't before Apollo 14 that we had color TV broadcasts from the moon surface. Apollo 11 had a b/w camera with them, Apollo 12 had a color camera, but Alan Bean immediately damaged it during the installation procedure, Apollo 13 failed to land, and here we have Apollo 14!
Best regards!
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Old 17th July 2019, 08:06 AM   #584
gpauk is offline gpauk  Scotland
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Yes... try not to point 70s tech cameras straight at the sun....

Apollo TV camera - Wikipedia
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Old 17th July 2019, 11:00 AM   #585
Tubelab_com is online now Tubelab_com  United States
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It wasn't before Apollo 14 that we had color TV
The gathering at my house was in 1971. It must have been from the second EVA since it was at night or early morning. Of course memories from that long ago are somewhat fuzzy.


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a few of us at work built the walkie talkie that he had duck taped to the window in the Space Shuttle. The first one was a hacked Motorola MX300 on 2 meters.
I remember that one because the guy who actually took the radio to the Cape Canaveral launch site sat across from me in the lab. He had a large picture of the radio duck taped to the shuttle window in his cube for several years. The shuttle was still on the ground when the picture was taken, so it must have been from early testing.
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Old 19th July 2019, 05:34 PM   #586
w5jag is offline w5jag  United States
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I put the cheap DDS on the RP to look at it, and these are the results.

The first bunch is 5.2 MHz - looks pretty good to me, except for the harmonics, everything else is -70 dBm or better. Fundamental is +7 dBm. It is pretty convenient to have the readout direct in dBm; should make level matching easier. The white background screen is an alternate spectrum analyzer program available on the RP Bazaar.

23.2 MHz does not look as good, a little less output ( 0 dBm ) but other than the harmonic, and whatever is going on at 56 MHz, all the junk is still below -50 dBm. I have not bought any of those Epcos 23.4 MHz bandpass filters, but will probably get some since they are pretty cheap, and some rf amp chips, and take another try at a couple of watt broadband output to drive the linear.
Attached Images
File Type: jpg 5 FFT.jpg (127.1 KB, 55 views)
File Type: jpg 5.2 Oscope.jpg (121.8 KB, 53 views)
File Type: jpg 5.2 FFT alt (2).jpg (98.7 KB, 49 views)
File Type: jpg 23.2 FFT.jpg (145.9 KB, 49 views)
File Type: jpg 23.2 Oscope.jpg (119.6 KB, 49 views)
File Type: jpg 23.2 FFT alt (1).jpg (87.7 KB, 12 views)
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Old 22nd July 2019, 07:28 PM   #587
bluerooster is offline bluerooster
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Originally Posted by JonSnell Electronic View Post
RF transmitters are not really DIY projects
Yes they are
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as even a CB radio can deliver dangerous RF burns to those who tinker.
yes it can.
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I would join the RSGB or some recognised amateur radio group.
good advise.
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Any power like that is illegal in most countries.
First I've heard of that. 80W illegal!? I guess my 1.2KW needs to be reported immediately.
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Old 22nd July 2019, 07:59 PM   #588
benb is offline benb  United States
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Originally Posted by w5jag View Post
I put the cheap DDS on the RP to look at it, and these are the results.

The first bunch is 5.2 MHz - looks pretty good to me, except for the harmonics, everything else is -70 dBm or better.
I have to wonder, (how) does the spectrum change with frequency? What's the DDS input frequency? I can imagine it looking clean if you're generating an exact submultiple of the input (like f/10), but move around a little and there might be grass everywhere.
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Old 23rd July 2019, 12:09 AM   #589
w5jag is offline w5jag  United States
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In general, with the DDS, I only checked around 5 and 23 MHz, and the upper limit of the DDS, because those were the only frequencies of interest to me at the moment. I put it at 5.2 and 23.2 to get off exact multiples a little bit. I don't recall seeing any increase in junk as it is tuned around.

It is kind of an inverse of the Si5351, which tends to look better as you go higher in frequency.

The DDS looks worse as you go higher in frequency. It has an RF board to amplify the output, and this is where all those harmonics are coming from.

My measuring capabilities and experience are quite limited, so keep that in mind ...

I've actually considered using the DDS as a 5 MHz tunable, mix it with an 18 MHz crystal oscillator ( built those last summer with the LM375 chip ), band pass the output, and use that for 23 MHz high side injection. It should be pretty easy - the DDS output is +7 dBm for an SBL-1, and since the output will need to be attenuated a lot for the AD831 and NE602 inputs, the SBL-1 output port can be broadband terminated with a big 50 ohm pad, before the bandpass.

Edit: of course I thought this whole thing would be a three or four week project tops, so ....

Hope that helps.
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Old 26th July 2019, 03:03 PM   #590
w5jag is offline w5jag  United States
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If I want to make another single conversion front end, using one of the Mini Circuits SBL-1 DBM's; 5 MHz LO , 9 MHz IF, and 14 MHz operating frequency, do I need to be concerned about all of the harmonics coming out of the DDS?

Should I low pass / bandpass the LO before it goes into the mixer, or just let the crystal filter deal with it at the output?

Also, I think I have some level 13 SMD DBM's; what adverse consequences can I expect, if any, if I only have level 7 drive? Increased conversion loss?
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