Hello all,
Here is some required reading for everyone. As we connected up our packet radio modems today, we need to learn how to use them! On the links page, I added a URL to an
Introduction to Packet Radio. It is a good read on what a packet modem does and how to use it. Please read this (at least the first two chapters) before our next meeting. We'll be getting those two packet modems talking to each other!
For the loop antenna that we made today, here is a refresher. We reviewed two types of connectors used with antennas: PL-259 (male) and SO-239 (female). PL-259 connectors are usually attached to feeds to antennas and SO-239 connectors are usually on the back of an amateur radio. (In the case of one of our radios, the SO-239 connector was labeled as "ANT". Easy, huh?) Also, remember that an antenna connector has a "tip" and a "ring". The tip is what usually carries the radio energy received at the antenna. The ring provides the ground for the antenna, to ensure the antenna is effective. In the case of a feed (the wire between the radio and antenna), if the feed were coaxial the ring would act as a shield around the tip to reduce interference, much like your cable TV coaxial wire.
To make the loop antenna, we cut a piece of wire to a division of 2 meters, the wavelength of the frequency band we're working on. The division we chose was 1/4 wave, only because I didn't have much wire hanging around! A better length would've been 5/8 wave (1/4 wave antennas aren't that great in terms of efficiency), or 1/2 wave, or the best -- a full wave (which would require a 2m long wire). In our case 1/4 wave was enough since the radios are so close together. So, we took 1/4 of 2m, which equals 0.5m, the length of our 1/4 wave antenna wire. I had a ruler with inches, so we converted 0.5m (50cm) to inches (50cm / 2.54cm = 19.7) ~ 20 inches.
We cut a 20 inch piece of wire, soldered one end to the tip of a PL-259 connector and the other end to the ring of the PL-259 connector. A random wire antenna would've just had the wire connecting to the tip of the PL-259 connector and no connection to the ring. A loop antenna is more efficient (not only because ours was a division of 2m) because it makes a complete circuit, from tip to ring (ground).
Mr. G.
NFA Ham Radio Club
Comments
Anthony Girasoli
Dec 3, 2009
Hey everybody,
I was able to get the PC packet modem to respond. You need to set the terminal settings to 9600 bps, 8 N 1. I tested it by connecting to RASON's BBS at 145.030 (N1NW-7). I'll show you at our next meeting and you can try communicating with their BBS to see what a packet BBS is like. I brought in a power supply for the Commodore 64 (C64) so now the C64 works. Unfortunately, the PAKRATT-64 packet modem does not work. I'll take the PAKRATT-64 home and see if I can fix it.
Mr. G.
kurttetrault
Dec 3, 2009
R.I.P. Pakratt64! I have a softmodem on my linux laptop and i presume that it works, I'll try to remember to bring the laptop to the next meeting, I was trying to bring it to the last one...
If there's anything you guys want me to look for that I might have (you name it I probably got it) I'll take a look for it and see if I can bring it in.
Kurt
Anthony Girasoli
Dec 4, 2009
Excellent, Kurt! I know you love Linux, so check out FBB... it's a free packet radio BBS that can run on Linux (even DOS!) http://www.f6fbb.org/
Also, I opened up the PAKRATT64 last night. It had a blown fuse. After replacing the fuse I noticed that one of the transistors was smoking. Uh-oh! I tested the transistor and it's bad. So, I'm going to order a new one, replace it, and let's see what happens...
kurttetrault
Dec 7, 2009
I often wonder where you get things like transistors and vacuum tubes here in 2009...
Also, on the FBB webpage, I am unable to download the compiled Linux distribution or the source code.
Anthony Girasoli
Dec 8, 2009
Kurt, you would be surprised. You can still get new tubes as musicians still use them in their amplifiers. They say tubes give a more "warm" sound than transistors. It is also very easy to get used tubes at bargain prices ($2 or less) that still work because tubes can last a loooooong time. There aren't many parts to a tube except metals, glass, plastic, and a vacuum!
Transistors are still widely available and wicked cheap (sometimes 20 cents). People still need them for repairing circuits, learning how circuits work, and even for amplifiers like in your stereo system.
As for the FBB software, you will need to use a FTP client to download the software. Did you also try one of the mirrors with an ftp client? LMK. http://www.f6fbb.org/udload.html
kurttetrault
Dec 10, 2009
You're going to have to show me which packages I need to get, I can't tell heads nor tails of the file names, x700b27-29.tgz for example. I confess that I'm really no good at linux, but I'm learning.
I've heard a lot about how vacuum tubes don't last very long at all? Perhaps you can enlighten me on this, and if I don't think I'll break it, I might bring in one of the tubes from my 20's era console radio and try to decipher what kind of replacement I need...