Tuesday, March 17, 2015

Desense

I had a little problem with my ham radio setup at home. I figured I'd post about it here just for kicks. I have two "base" radios at home. One is a dual-receive Yaesu FT-8800R that I use to monitor local repeaters. My second rig is an Alinco DR-135 that is connected to my Allstar node. The antenna for my Yaesu is up in the attic above the garage. The antenna for the Alinco was in the garage below.

The Alinco is a 2-meter radio. I run it at 5 watts. When my Allstar node is connected to another node/hub, the Alinco transmits whenever there is activity on that node/hub. The output of the Alinco was essentially "desensing" my FT-8900. The symptom being that the FT-8900 suddenly became "hearing-impaired" whenever the Alinco was transmitting.

I typically monitor the Alinco radio from inside the house on my HT. And 5 watts is way more than I need for that. Unfortunately, regular mobile rigs don't usually go lower than that.

I tried moving the Alinco node radio into my office in order to gain a little more distance between the two antennas. But even on low power the RF got into some of the electronics in the room which made that an unworkable solution.

After considering a number of other possibilities, I decided to take the antenna off the Alinco node radio and swap it with a dummy load. I tried this last night and it seems to work really well. I located the node right in my office and the RF no longer interferes with any electronics. And the dummy load allows enough RF to pass where I can talk though it from my HT with no problem.

Sunday, February 15, 2015

Gear swapping

After concluding a couple of weeks ago that I wasn't going to be able to do HF here at home, I sold all my HF gear on eBay. I sold my Yaesu FTdx1200, my Buddipole and my Comet antenna analyzer. I also sold my Signalink (since it's intended use was on HF).

I got pretty good prices for what I was selling. I actually sold the FTdx1200 for only $45 less than what I'd originally paid a few months back. So I'm officially out of the HF business.

After selling all that gear I decided to make a few more changes. I have a node radio (a Yaesu FT-7900R) that I use with my Allstar node. I've been running it on 5 watts, but even 5 watts is overkill just for my local use. And it's certainly a much nicer rig than what is required for a node radio.

So there's this guy that obtains used commercial radios and resells them along with the necessary control cables for use as node radios for both Allstar and IRLP. You can't just spin a dial and put these radios on the frequency you choose. These radios must be programmed via special software for the frequency and tone you wish to operate on. And that's part of the service he provides.

So I ordered a GE MVS commercial radio for use as my node radio. And I requested he set the transmit power level to 500mw. It will be very sweet to have a commercial radio as my node radio that only transmits with 1/2 watt. Should be about perfect. I talk to my node radio with my HT on it's lowest power setting which also happens to be 500mw.

I had been toying with putting my current node radio (the FT-7900R) in the car, but decided against it. Instead, I bought a second Yaesu FT-60R for mobile use and put my FT-7900R up for sale on eBay.

My wife and I switch cars fairly frequently. So it is really better that I don't have something permanently mounted in a vehicle. What I will have is a mag-mount antenna in each vehicle. And I'll move my FT-60R back and forth as I switch vehicles.

Friday, January 30, 2015

Node relocation

I've learned a couple of things about running an Allstar node. Nothing too earth-shaking.

1. The mobile radio hanging off the node computer can spend a LOT of time transmitting. Typically a non-commercial ham radio is not rated for this sort of duty-cycle. But I'm hoping that having the power set to the lowest setting (5w) will make a difference.

2. I've been experiencing a high number of dropped cellular calls. I don't know for sure, but it seemed that most of the dropped calls happened while sitting 3ft from my node antenna. And these dropped calls probably happened while the node was transmitting. It is for this reason, as well as general RF safety that I decided to relocate my node to the garage (see pictures).

3. Technically I'm supposed to be monitoring the node at all times and have the ability to turn it off if need be. That is part of the definition of a "control operator", which every ham station must have. However when someone is using my node, they are transmitting and my node is not. When my node is receiving RF it is sending VoIP out over the net, but it would be the repeater or node on the other end of the connection that would be transmitting. And for that I would not be responsible to the FCC. The repeater or node-owner on the other end would. My node would only be transmitting what gets received from the repeater or node that is on the other end of the VoIP connection.  Of course the repeater or node-owner on the other end may block me (and be justified in doing so) if someone on my end is abusing my node.

As part of the move out to the garage I set up a spare router that runs the Tomato open-source firmware to act as a wireless bridge. It connects to the wireless router in the house via WiFi signal and connects to this PC via ethernet. It's not that different than having a wireless card in the PC, except that this PC runs an ancient version of CentOS Linux that probably has really iffy support for wireless cards. With the bridge it only needs to support the on-board ethernet.

Sunday, January 11, 2015

How to setup an Allstar Link simplex node

Check out these three links:

Allstar getting started info: https://allstarlink.org/getstarted.html

URI: http://www.dmkeng.com/URI_Order_Page.htm

Cables: http://www.uricables.com/

The Allstar folks are the ones who offer the ACID Linux distribution which has all the software you need to run a node. Much of it is preconfigured. It's essentially CentOS 5.11.

So, buy the URI and the right cable for your radio. Download ACID Linux and install it on an old PC. And hook up the radio. Then configure and adjust the audio tuning in the software.

Most all the configuration can be handled via the Allstar portal. You set the configuration there and and it actually pushes it onto your computer. You do need to setup port forwarding on your router for this to work.

If you wish to enable Echolink, you need to forward those ports as well. This software will do Echolink with very little extra effort. But you will want to change your callsign to have the -L suffix and switch it over to "sysop" mode.



Monday, January 5, 2015

Simplex node

Because of a recent VHF/UHF radio purchase, I ended up with a "spare" dual-band radio. And, I've been having some fun lately monitoring the WIN System on a local repeater (that is connected via IRLP). So I figured I might try my hand at setting up an IRLP simplex node. I've had some experience with IRLP in the past and have really enjoyed it.

However as I was looking into it, I started hearing about Allstar. That is an alternative to IRLP. It's a little cheaper to get started with Allstar, and it offers full-duplex operation. And it uses standard open-source VoIP software to do it's thing.

So here you see my main computer, and next to it is a $45 Goodwill special. It's a Core 2 Duo with 1GB RAM and an 80GB HD. Pretty wimpy, but more than enough to run the special Allstar Linux CentOS distribution. This Linux distribution comes with all the stuff needed to run an Allstar node and does the setup for most of it.

So I've applied for and received my node number. I went ahead and finished the Linux installation last night and that's all good.

The only things I had to buy (besides the computer) were the URI (USB Radio Interface) and the URI cable. The URI plugs into a USB port and the cable connects it to the radio.

Now patiently awaiting those last two pieces.

So in theory... once this is all complete... I should be able to sit on my couch with my HT and talk to my node radio in the back room which will control the node. I can connect to other nodes all over the world with a few DTMF commands. And the connection quality should be rock-solid and full-quieting.

Plus, I have a neighbor who is a ham. He should be able to use it as well.