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Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Hi folks
As a follow-on to the amateur radio thread I decided to post a few pictures of my radio equipment. Also because I want to figure out how to attach multiple images to a single post and whether you can add captions to them. (edit: you can add captions but it's a fiddle)
I welcome any comments and suggestions on how to improve my home made antennas
Images:
*2m rig, HF rig, HF antenna tuner.
*J-pole antenna for 2m made of copper wire, electrical tape and plastic drain pipe under test in the living room. Seems to work fine, can access several local repeaters. Will be moved to the loft.
*Guts of the home-made HF antenna tuner, made out of an ammo box and some nice capacitors off eBay.
*Middle bit of the 33ft dipole, with its 1:1 air cored balun. This was strung out through the apartment for testing, and moved into the loft as soon as it worked. It tunes up fine for transmission on 10, 14 and 18MHz, and works all right for receive on the other bands except 10m where it's completely useless. (it's exactly the wrong length)
*My most ambitious ham project, a partly home-made 13.8V switched mode power supply. I rebuilt a 5V, 50A Astec switcher for 13.8V, 20A and added extra RFI filtering.
Registered Member #16
Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554
Looks great Steve! Hopefully once I get my tower up, we can have a proper QSO. My new 135' dipole should be up in a few weeks atop a 70' tower. I'll post some photos of my shack over in the Amateur Radio Thread tonight.
My suggestion for better performance on the higher frequencies might be the biggest single turn magnetic loop you can possibly manage, and an Low noise preamp right at the feed point of the antenna. It might be more effective in that situation than a dipole. You need PSK31! 50w would easily get you anywhere in the world, even with a crummy antenna. I worked EM1EO in Antarctica on 14.070Mhz recently with 25w into a 66' inverted V up only about 20 feet.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
Nice set-up Dave. Your one of the youngest guys I know that is involved with amateur radio. One of my best friends in really involved in it, but he is about 75 years old! heh heh
Anyways, i've been planning on getting involved in amateur radio myself, but am more interested in the antique part of it - building old tube based transmitters / receivers.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Steve can I ask for schematic of that SMPS, i love to collect them You said its partially home-made so does it mean you have/you don't have a schematic..
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
I don't have a schematic. When I got stuck trying to get it to work, I called Astec and asked for one, but they said no way. They explained that they don't give the schematics out because they don't want competitors copying their designs. As a last resort, I tried explaining to the Astec engineer what I was trying to do, and he laughed and said I was nuts or words to that effect.
Well, I got it to work anyway, so Ha-ha Mr. Astec. Here is the archive thread that describes the mod:
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
I wa thinking to build my own high-power SMPS (over a kilowat) but I need planz ... lol..kidding... actually need core for the transformer for that amount of power, flyback cores are biggest (I have some really large ones) but they are still < 500W... I dont have indentical cores so paralleling them is not an option.
If I dig some SSMOTS out of junk (one day) and use their mighty core (few kW) to wind my own transformer.
I intend to copy most of computer ATX parts, use Sg3525 or TL494 or so and two IGBTs as drivers...
For low powers most interesting are computer atx SMPS, so its pointles to make something like that (cost few bucks in computer shop)
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Steve's Radio Shack
Here is the archive thread that describes the mod: 