HAM Radio/Hardware Hacking

Teaching myself radio

Wed, 11 Jan 2012 08:47:06 +0000

So I looked up spark-gap transmitters, Poulsen Arc-Converters, and I'm working my way to vacuum tube tech. Most of this is learned off wikipedia.

What I'm looking for from you guys is info on:
+Antenna design
+Practical materials on building/designing primitive radio gear
+Anything else that's relevant, since I'm just getting my feet wet and can't even tell you what I'm supposed to learn

PC relay controler

Sun, 27 Nov 2011 03:44:55 +0000

I am interested in setting up a PC to control some relays.
I do not currently have any solid plans for what I will use this for
I will be using one of my unused PCs so OS installed would depend on what drivers are available.

I would like:
expandability - so far most of the stuff i have found online are projects that will only handle several relays. I would assume that I would eventually want at least several dozen relays connected, if not more.

internet access to activate relays, should be able to be accessed by smart phone - telephone access would also be a useful feature, but not really required (ability to control individual relays by calling into system - would be great to allow temporary access to a locked location, example for a maintenance worker)

ability to monitor status of individual relays

ability for individual relays to operate with a timer as well as being controlled by commands inputted on remote device.

does anyone on here have any experience in setting up any PC controlled relay systems?

Ham Radio Licenses at an all time high.

Wed, 23 Nov 2011 01:21:29 +0000

http://entertainment.slashdot.org/story/11/11/22/1523249/ham-radio-licenses-top-700000-an-all- time-high

Stupid power supply question

Wed, 16 Nov 2011 22:05:30 +0000

So I'm trying to put together a replacement power supply for a DVR I snagged today. The original was configured as such: ftp://files155.cyberlynk.net/uploads/Classic%20Recorder%20Power%20Pin%20Out.pdf

It needs to put out +12VDC, +5VDC, and -12VDC. At first glance, I'd think a plain old AT power supply would work fine, since it would put out +12VDC and +5VDC at more than sufficient amperages.

But what about the -12VDC? As I understand it, -12VDC is merely +12VDC with swapped polarity. But I don't know how I'd be able to get + and - out of the same supply without shorting its outputs to its grounds.

Can anyone enlighten me on what I'm missing?

--nwbell

Antennas

Wed, 16 Nov 2011 18:43:09 +0000

Anyone have recommendations on antennas? I have a city lot sized property with the house square in the middle. So roughlly 30'x50' in the front and back yards to play with. Don't really want to put a tower or flagpole up (will probably move once the market recovers in a few years) and am trying to avoid putting anything on my roof (am against drilling holes into a roof for fear of leaks).

Already have a pair of M2 Eggbeaters for satellite work that I still need to get the appropriate mounts for my roof eaves. Looking at a vertical somewhere on the yard since my ATAS-100 sucks ass being mounted to the house without a proper ground system which I'll probably install sometime after the first of the year.

Commercial Wireless spying hardware details leak

Thu, 03 Nov 2011 02:03:29 +0000

http://cryptome.org/0005/stingray-spy.zip

Stingray hardware that lets you find people using various wifi devices. Keep in mind the document scan looks like its from 2008 (but it was just leaked on october 27th)

Direction Finding

Thu, 21 Jul 2011 10:40:58 +0000

Any suggestions on DF setups or antennas? Looking around I found some interesting designs but some don't seem that practical. Adjustable is better, but currently hunting a 300-400mhz signal of unknown location.

I was planning on using something like this although I'd have to make the arms a bit shorter for my frequency (I think.)

What's needed for the multiple antenna setups?

Freq ID'ing

Sat, 16 Jul 2011 13:20:16 +0000

Scanning about with my R20 found something strange (to me anyway) what appears to be a trunked talkgroup at 3151mhz, I believe it's public safety related. I looked on the FCC, Radio Reference and CityFreq, and couldn't find anything.

Planning on setting it to VOX record on my PC and letting it hang out for a while. How can I track the talkgroup? Trunker + R20 + Optolinx or the Icom variant? Just try the separate channels?

Wideband Reciever

Wed, 29 Jun 2011 20:58:56 +0000

Well since I derailed my own thread from freq counters into wideband scanners I decided I should start a new thread before I get too far into it..

Attempting to find a reasonable priced wideband reciver!

I would love to find something like the AOR AR5001DU for cheap but I don't see that happening so I'm looking for used suggestions preferably less than $500.

I want to find, listen, and record to my pc.
Will be a desk unit so portability is not a necessity.
Maybe an SDR is what I need? (Something like a Icom IC-R2500?)
More frequency range and smaller steps is definitely a bonus.
I'll add more if I think of any..

Virtual Downcoverter mods? BC 8500 XLT

Wed, 29 Jun 2011 12:50:15 +0000

I was reading TICOM 3 and it mentions Virtual Downconverter mods, I have a BC8500XLT, the BC8500 is mentioned, but nothing about the XLT.
Unfortunately it doesn't provide much additional information on it.
Would it work on the XLT? (I think so)
What does it do exactly? (Changes 371.19-396.80 MHz, to 869.04-894.97 MHz)
How is it done? (Switch?)
Found this that indicates it should work on the XLT but it is a bit over my head:

Quote

swap the logic control lines that drive transistors

From the above and also of interest:

Quote

There are a couple of other things you can do with the BC8500 that we documented in the former RCMA Journal.

if anyone has a line on those too?

transmitting license

Sun, 19 Jun 2011 03:36:59 +0000

I didn't wana hijack some other guys thread so I made a new one....basically I would like to know the probability of transmitting lets say 20kms inside a large city in the USA without a license and gettign caught...anyone have any experience with this? Just curious as I don't have the means to do so even if I wanted to

Need schematic for FM transmitter ~100 Watt to start Pirate Radio Stat

Wed, 15 Jun 2011 14:25:38 +0000

Hello i need a schematic for a ~100+ watt FM transmitter. I want to be able to broadcast for 10-20 KM. 100 Watt should do the trick, right?
Anyways, can anyone provide a circuit?
I will be broadcasting on the 100MHZ Frequency band in the FM. My Antenna is mounted 50 feet above ground. Is this high enough?

I looked up at a transmitter, but I don't want to shell out $500 for this, i'd rather buy the parts and build it myself.

Please, I really want to do this.
Also, What length does my antenna have to be?
Yes, I will also stream it online so others can listen.

has anyone done anything with MRAM or FeRAM?

Sat, 23 Apr 2011 22:21:38 +0000

Just wondering with those nonvolatile technologies around if anyone has done anything with them. If they replace both RAM and hard drive (on a small embedded OS of course given the lack of memory on these things), won't programming be way different? After all a memory leak could seriously mess up your system and you can't just reset your way out of it... Just wondering how programming would adapt to that.

DIGIAC 3000 Computer Based Training System

Fri, 11 Mar 2011 18:37:28 +0000

Ok, so there a windows xp computer, running SP3. Attached to the USB is a serial/usb adapter which is running to a DIGIAC 3000 as part of an A-level electronics course. When the programing software is run, it generates the error: Check cables; Communication/Power error - or something along those lines. I can't remember exactly.
On the DIGIAC is a pic micro controller, on a development board.

Could anyone shed some light on how to fix it, or point me towards some manuals or something?

Desoldering Components with a Woodstove

Tue, 01 Mar 2011 13:16:54 +0000

I needed to desolder a bunch of LED dot matrix displays last night, and didn't want to resort to soldering iron + wick since there were 20 displays to be removed. I figured, people use electric skillets for reflow soldering, so I should be able to use my woodstove, right?

http://glitchwrks.com/desoldering.html

It worked perfectly...no boards-on-fire or smoke, and all 20 displays came off in about 15 minutes.