Wednesday, November 8, 2017

2017 Update: VHF Repeater on air!

The repeater is back up, albeit in need of a little work. It's in a new location with a new antenna pattern. Coverage favors downtown Birmingham and covers the entire UAB campus, and has emergency power.

Wednesday, August 31, 2016

2016 Update

We are still here, not much to post. Tower was removed from CH19 by the university before paint could be applied about a year ago, after the top section rusted through the previous year's paint. The repeater atop the hospital remains in that location, but since access requests have been denied, the repeater has been taken off the air (turned off) until an emergency results in the necessary access being provisioned. Steps are underway to move the repeater to an area that is under campus control due to necessary changes as a result of effective building ownership.

As always, a human can be reached at We encourage membership, but much like the Freemasons, if you want to be one, you have to reach out and make first contact.

Thursday, December 29, 2011

New Repeater Installed!

Hi All!

This is my first update in a long time. So, in the background, there's been a lot going on as far as putting the station together and a few other things. I spent a few dollars on a backup repeater and bought a new receiver drawer for the repeater, only to find out that I could have told the crystal manufacturer to set the crystals up for high-side injection instead of the stock low-side injection. Oh well, you learn. The Pion and Simon controller is programmed and in place, along with the station itself. It has been reunited with it's power supply and cabled up to the duplexers. I'll post pictures when I can get back up there. As it left the workbench, the repeater was putting out just slightly more than 50W from a 110W continuous-duty rated power amplifier. Once the new circularly-polarized transmit antenna is built and installed, the power will be raised to according to the radiation pattern of the antenna.

The repeater's coordination is at 50W, but that also assumes that it is vertical radiation only. Certain circularly polarized antennas radiate more power into the horizontal than vertical field or vice-verse. Technically, this is called elliptical polarization. If the antenna radiates 25% horizontal and 75% vertical, then I can bring the transmitter power up to about 67W. At 50/50, I can set the transmitter to 100W and still maintain compliance with coordination.

The repeater is mostly a shell of what it formerly was. Changing from "66" to "55" required replacing the transmitter, transmitter power amplifier, and the receiver. Fortunately, with the addition of the PSE-508-2, most of the cards in the station became unnecessary. The remaining modifications were made to the 10V regulator per the repeater controller web site, making this a very smooth deployment, considering the considerable research that went into checking the radio out and discovering the hold-up that was the receiver band selection.

The repeater controller also has a voice chip in it, and this will be used in the near future. But for now, it's up in the loft where it lives, 52W and 4.5KHz deviation...

For those who are interested in the technicals:

Courtesy tone is 1200 Hz, at 50% level
IDer is at 1000Hz, at 50% level.

This means you can check the deviation of the repeater using the IDer tone... which should be about 3KHz, plus ~750 Hz CTCSS deviation. Total deviation from the repeater, CTCSS and audio, is set to 4.5KHz, per GE specs. The repeater is a 110W GE Mastr II continuous-duty rated station.

Sunday, January 9, 2011

Tower Stripped

In preparation for the installation of new equipment, the tower has been stripped.

Saturday, February 2, 2008

UAB ARC Website Established

This is the website for The University of Alabama at Birmingham Amateur Radio Club, WB4TJX. This has been an active club at UAB since 1976. The club has a station, equipped with a three-element multi-band HF yagi, as well as a two-meter vertical (Cushcraft Ringo Ranger), and a repeater on 145.23 MHz (input -600KHz, 144.63MHz, PL tone 203.5Hz). The repeater covers most of downtown Birmingham, but due to terrain, does not provide coverage south of Red Mountain or north of Warrior.

For further information about WB4TJX, or the UABARC, please find our email address on QRZ.COM.

Repeater Coverage