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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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1st Dec 2017, 6:20 pm | #21 |
Nonode
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,562
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
Hi Bazz.
Yes that could be a little problem finding the correct socket at a reasonable price. I suppose it's feasible to make something suitable using individual sockets set in a resin to the lead pattern of the 6CW4. Regards Symon. |
1st Dec 2017, 6:23 pm | #22 | |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
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I'm sure someone on the forum has one. It's not a show-stopper, in any case. They're tiny and the leads need to be short because of the frequencies involved. It would be possible to make a case or solder directly to the pins.
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1st Dec 2017, 10:24 pm | #23 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,924
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
Of course, many of the Soviet Nuvistor clones have wire-ended connections. I've never used one, but it is probably quite a good idea. If you drill a hole through a piece of copper-clad board, you can sit the Nuvistor in that with the bottom of it just slightly higher than the copper. The leads then come out at 'component height' on the board. That's what I've done a couple of times with socket type Nuvistors. My last Nuvistor project was about a year ago, when Skywave and I were in pursuit of sensitive, wide-range RF voltmeters, an area where outcomes were mostly quite disappointing .
Was it just coincidence that this thread started with a mention of Voyager, and BBC4 showed a truly excellent documentary about Voyager last night? Don't think I learned much that was new, but sat riveted to the TV. One bit that was new was the last minute panic, prior to launch, which lead to them wrapping lots of wiring in the spacecraft using "Bacofoil" from the corner store just down the road from JPL. They conceded that some standard design and procurement procedures at JPL may not have been "fully" complied with during that activity! B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. Last edited by Bazz4CQJ; 1st Dec 2017 at 10:34 pm. |
1st Dec 2017, 11:30 pm | #24 | ||
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
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The other thing to say is that the table gives HF performance (shot and partition noise). For VHF and up you also need to take account of grid noise and grid input conductance. That is where valves like the 6AK5 score: at HF it is no better than many RF pentodes (and worse than some) but it deteriorates less as the frequency goes up. |
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2nd Dec 2017, 4:33 pm | #25 | ||
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
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Not everyone 'gets' this as this space listening isn't communicating intelligence/ what we define as 'meaning', but just as I enjoy the challenges of controlling unwieldy amounts of power electronically, so do I enjoy the other end of the spectrum, seeing uV or uA signals in a receiver front end!
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Al |
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2nd Dec 2017, 6:00 pm | #26 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,924
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
Curiously, there was a brief mention of one Voyager on the news today. It seems that the main thrusters, used to orient the spacecraft to point its antenna towards home, are degrading. So for the first time since 1980, they tried firing the backup set and they performed 100%. Way to go !
B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
2nd Dec 2017, 10:49 pm | #27 | |
No Longer a Member
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Location: Maroochydore, Queensland, Australia.
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
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Imagine how beautifully made this spacecraft is both with the physical construction and the electronics. Probably has radiation hardened TTL's for a lot of its logic circuitry and more than likely the entire craft does not contain a single electrolytic capacitor ! |
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2nd Dec 2017, 11:50 pm | #28 | |
Dekatron
Join Date: Nov 2006
Location: London, UK.
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
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Avionics wiring looms seem fascinatingly complex and intricate, to me, almost like a being... I remember seeing a cross-section of I think an Avro Vulcan, just incredible.
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Al |
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3rd Dec 2017, 2:56 am | #29 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
I've attached an image of a 1969 vintage Intelsat 3 satellite, which gives an idea of the internal construction standards.
I was told that one of my electronic dynamo regulator designs for vintage cars got built in the Intelsat workshops by an engineer who was a British car enthusiast, but I never got to see a photo of it, no doubt it would have been better made than anything I could have dreamed of. |
3rd Dec 2017, 6:05 pm | #30 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,924
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
Even more interesting; probably the biggest techonolgical secret this country ever had was the 1970’s-80’s “Chevaline” project. This was a UK-designed mid-life update for the Polaris nuclear missile. These days you can find endless pages about it via Google. But at the time, it was most secret, mainly because successive Governments hid the huge cost (mostly over-spend) from Parliament for the best part of a decade. Only Mrs T had the nerve to finally make it public.
There’s an overview here https://en.wikipedia.org/wiki/Chevalineand some pictures here https://fas.org/nuke/guide/uk/slbm/chevaline.html. Unfortunately no clear pictures of the electronics, but discrete components on solder-tag boards were predominant. It's important to recall, this unit was effectively a fully stabilised spacecraft, albeit one which spent a very short time in space! It was replaced by Trident around about 1992 and many people were “a bit surprised” that a number of the Chevaline vehicles (minus their shrouds and fully exposed as in the pictures above) were soon put on display in museums (I was there on the first day they were on display). After some months, however, these were hastily withdrawn from display, had various bits removed and then returned to the museums. Of course, these days, we just buy stuff from overseas. B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. Last edited by Bazz4CQJ; 3rd Dec 2017 at 6:11 pm. |
3rd Dec 2017, 6:08 pm | #31 | |
Dekatron
Join Date: Nov 2006
Location: London, UK.
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
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It was quite a careful dissection for my age and I kept the most impressive looking components and tried to find out what they did: not easy as I didn't have a mentor of any kind, but I was quite patient. I remember being very intrigued by the big multi-gang tuning capacitor as well as by the internal construction of the valves.
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3rd Dec 2017, 6:21 pm | #32 | |
Dekatron
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
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Someone asked him "How long will this equipment be live for?" He replied "something like 20 years" at which point his questioner said "if it takes 20 years from launch for your missile to hit its target your company's out of the contract!". Strategic nuclear missiles - do they come with an "Explode-by" date?? |
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3rd Dec 2017, 8:17 pm | #33 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
Just a tip if anyone wants nuvistors: look out for Tektronix 1A1 or dead 453’s with serial numbers less than 20,000. They have two socketed nuvistors in the front end and a whole world of reusable parts. If they are beyond repair it makes sense to recycle accordingly.
I’m ashamed to say I had six dismantled 1A1’s I got in an eBay auction for £5 which were stuffed with nuvistors and sockets. They went back on eBay thinking I’d never have a use for them. Went for £75. Nearly fell off my perch! |
3rd Dec 2017, 8:50 pm | #34 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
I'd like to stick up for the humble field-effect transistor.
There have been some very good FET-based VHF converters over the years. Many from a period now considered classic. They're in the RSGB handbooks, or the circuits of the microwave modules ones can be found. If you want to be very posh, you could clone one of the Mutek front-ends. Chris Bartram made a very good job of those. Low noise small signal VHF work is where transistors are getting into their strengths and valves are starting to have difficulties. In order to be a compleat electronics guy, you need to understand valve gear because there is still a lot of nice classic valve gear around. But you also have to understand transistor stuff because it has some great tricks up its sleeve and there is also some rather nice solid state gear around. Both sorts have some real stinkers, of course. David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
4th Dec 2017, 4:12 pm | #35 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
Must admit, for VHF converters I always liked the double-balanced-diode-mixer approach [MD108/SBL1 etc] - their strong-signal-handling capacity being a particular feature, important if you've got any powerful two-way or broadcast-transmitters in the area.
One of these with a low-gain RF amp [grounded-grid/gate/emitter stage according to taste?] coupled with loads of local oscillator drive to ensure the mixer really *is* being switched by what amounts to a square-wave, will get you going. I did once build a VHF converter with push-pull 6J6 double-triodes as RF amp and mixer, as the only way to hear 2-Metre signals when I was line-of-sight to the Blaenplwyf VHF Band-II transmitter and its hundreds of Kilowatts..... |
4th Dec 2017, 4:46 pm | #36 | |
Dekatron
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
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B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
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4th Dec 2017, 5:43 pm | #37 | |
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Re: Home brew converter to listen to Satellites, plus capture of Voyager TX by NASA
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Best not to discuss cars in these forums though.
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
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