The Ashwaubenon (High School) Tech Club

[147.075 MHz - N9DKH]

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The Repeater  147.075 + PL 107.2 / DCS 223

1994 - The Birth Of The 075

The 147.075 repeater was originally constructed by Andy, KB9ALN.  It consisted of a Motorola Spectra-Tac receiver, a Micor transmitter, the CAT-100 controller and a set of Waycom duplexers.  Also installed , was a converted Micor High-Band Preamp, and a Motorola repeater test set. 

We had a Realistic WeatherRadio Alert III interfaced to the controller so anytime there was a weather alert, a series of paging tones and voice message would go off.  "Weather Radio alert, check 162.550 MHz for information."

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It actually started off using an Alinco HT with a fried receiver as a transmitter, and Andy's Regency R-1070 scanner with a rigged COR as the receiver (and a strip line filter) with the CAT-1000 as a controller slapped into a metal cabinet that Chad junkpicked.  This was for testing and programming of the controller in Chad's basement.  Basically to keep Chad occupied while Andy did all the rest of the real radio work.

At this point it was mostly us using it, but we did have some people checking it out. It was hooked up into a homebrew Super J-Pole (developed by the Independent Repeater Association) while at Chad's house and surprisingly despite everything, it worked pretty well.  Later when we moved to the high school, we used a dual-band Diamond antenna.

The original repeater cabinet was donated by Dennis, KB9ABO. He gave it to us along with a UHF business band repeater that we ended up scraping or selling parts of it. They kept the fan from it though.  The club ended up getting a second cabinet donated to us from a guy in Chicago that Scott knows and we took a road trip down there to pick it up, but we never ended up using it.

Another nice feature that Andy took the time to do was make our repeater's outgoing tone (107.2 Hz) squelch crash resistant regardless of any radio's PL turn of method.  This always made listening a pleasant experience.  He accomplished this by a homebrew 555 timer circuit that would keep the transmitter up briefly after the encoded PL tone was turned off.

Club room at the high school:

As mentioned on the main page, the shack was in the back of Room 140 of the high school.  It was constructed to house the repeater and radio equipment, mainly as project by Paul Zochert. He was not a ham, but a friend of Chad's.   It was built with wooden studs and drywall, a plexiglas window, and locking door.  We had backup power installed from the school's generator, and a phone line installed for autopatch and remote repeater control.  

In the shack, there was a rigged a motion detector alarm and cabinet alarm to the repeater controller for added protection, which triggered a two tone and DTMF alert which triggered our Minitor pagers (which the mighty Zed [Steve, KE9LZ] tuned up for us). The pagers were also used as a LiTZ alert, weather alert, and general paging for fun. They were also occasionally used as an alarm clock for Chad, with the message "P A Y get up".


April 2005 - Repeater Rebuild

The repeater has been rebuilt as of April 2005.  The transmitter and receiver have been replaced by a Kenwood TKR-750.  The CAT-1000 controller will remain and a weather receiver with SAME technology has replaced the Radio Shack Weather Alert III.  

The weather receiver to programmed ignore some of the more annoying nonimportant messages. When a matching alert is sent by the weather service, it will be heard on the repeater as it will be retransmitted, much like how it breaks in on TV. For the duration of the weather event a special weather file with custom courtesy tone is loaded.

We have a 110 amp-hour back up battery system.  (We are the backup Brown County Skywarn repeater).  We have also configured an encode and decode digital PL tone of 223, as this is more pleasant to listen to than squelch crashes.  There will be other improvements as well.  You can now connect to the 147.075/R remotely using IRLP or EchoLink This is ideal for a number of members that have been transplanted or are frequent travelers.  Click here for information on how to do so.

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Present Day 147.075 MHz System Hardware

Aluminum - mono band  5/8 over 5/8 collinear , 7 dBd gain, shunt fed DC ground with a female N connector

1.5 dB loss at VHF per 100 feet

Coaxial line lightning protector 50-220 MHz, type: IS-50NX-C1 with female N connectors

4 cavity BandPass/BandReject Duplexer- 1.5 dB insertion loss, providing 45 dB isolation

20 db Gain (9 dB gain usable sensitivity),  1 db Noise figure - uses a high-Q tuned input circuit to pre-select the desired frequency range, restricting the strength of other out-of-band signals. 

Self-contained 25W continuous duty rack mount VHF base station/repeater.  Accessory/logic controller connector (25 pin) and test-speaker-AUX connector (15 pin).

Linear VHF repeater rack mount, thermally protected.  25/160 watt with RF Bypass relay and N connectors

Full-featured repeater controller. Remote base port, autopatch, voice synthesizer and with DVR

Programmable digital SAME (weather warning) decoder to provide NOAA audio retransmission and custom weather signaling.

Solid state, linear, low ripple, 50 amp continuous, 60 peak, rack mount with meters

Instant switching 40 amp continuous isolated backup power system, with 4 stage battery charger

Pentium III @ 1 GHz w/ 512 MB RAM running CentOS 5 with a version 3.0 IRLP board