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Oakland

Page history last edited by Jeffrey Komori 10 years, 9 months ago

We are working on a site in Oakland to cover APRS 9600 Baud on 145.71 MHz as well as APRS 1200 Baud on 144.39 MHz.

 

Here is the view from this location (looking towards the SF peninsula):

 

David "Zonker" Harris, N6UOW, hard at work installing the antenna and doing a little tree-trimming:


 

We want the equipment used at our Digi/I-Gate sites to be robust, reliable and good "RF" neighbors. To that end, wherever possible, we will be using "Commercial Repeater-grade" equipment. Of course, funding is limited (I do have to pay rent and eat food, etc) so this isn't always possible.

 

To that end, we've selected the Advanced Communications Systems for our transmitters and receivers. They are crystal controlled radios and have crystal ovens for frequency stability.  Because they are crystal controlled radios, they lock onto the frequency instantly and don't "search" for the frequency like synthesizers do.  Also, there is no hash noise that a synthesizer would generate. The receiver units have extremely good front-end filtering and can withstand adjacent channel/band interference and still perform well.  The transmitters are 100% duty-cycle and can even withstand a no-load situation (coax or antenna failure).

 

We've selected the Stridsberg Engineering receiver multi couplers for sites that will function as dual (1200 & 9600 Baud) I-Gates to minimize local oscillator interactions between the receivers connected to the same antenna. This multi coupler has an active preamp to minimize losses due to splitting the received signal from the antenna to the two receivers.

 

To protect our investment, we've selected the Alpha Delta line of coax surge suppressors that uses a gas discharge fuse to help minimize lightning strike damage.

 

While considering the power for the radio and the computer, we selected the Apple "unibody" Mac Mini (Macmini5,2 / mid-2011 mini) since it uses an internal 12VDC@7A switching supply; bypassing the internal power supply allows us to use the same rack-mount 12 VDC power supply we use for the rest of the equipment by retrofitting the logic board interconnect with a header-to-Anderson Power Poles interface.

 

To power our station, an Astron RM-12A-BB linear 12vdc rack-mount power supply with built-in battery backup system is being used. A GSM sealed rechargeable battery (28AH) is attached to the power supply.  DC power distribution goes through the West Mountain Radio RIGrunner 4008H (a 12vdc power distribution power panel that uses Anderson Power-Pole connectors for input and 8 output with all ports protected by blade fuses). The power consumption measures in at approximately 33 watts continuous power.

 

 

The cubicle space of all this gear comes in at 10U (17.5 inches).

From top to bottom:

3U, ACS MR-4 Rack Receivers (144.39 MHz - 1200 Baud 

3U, ACS MR-4 Rack Receivers (145.71 MHz - 9600 Baud

1U, left side of shelf-Kantronics KPC-9612+, right side of shelf-MacMini

3U, Astron RM-12A-BB power supply

 

 

We have installed the following parts for this project:

 

Power:

Astron RM-12A-BB (13.8V, 12A intermittent/8A continuous rack-mount linear power supply w/battery backup feature)

West Mountain RIGrunner 4008H (12V power distribution panel using eight Anderson PowerPole connectors)

PowerSonic PS-12280NB (12V, 28AmpHr Rechargeable AGM Sealed Lead Acid Battery)

 

Antenna:

Hustler G6-270R (144/440 Dual-band High Performance Gain Vertical Antenna)

Times Microwave LMR-400 Low Loss 50 Ω Coax Cable

Times Microwave TC-400-NM N Male LMR-400 Crimp Connectors

Times Microwave TC-400-BM BNC Male LMR-400 Crimp Connectors

 

Data:

Apple Mac Mini (2.7GHz Dual-Core Intel Core i7), 8GB RAM, 500GB Seagate Momentus XT Hybrid 7200rpm/Solid State Drive)

Mac OS X Mountain Lion (standard edition, not the server edition)

JavAPRSSrvr v4 (Java based APRS-IS Software) 

TrendNet USB-to-Serial Adapter

DB9(Female) to DB25(Male) Adapter

Kantronics KPC-9612+ (dual port 9600/1200) TNC

Shielded Audio Cable from Heil Sound

 

RF:

Advanced Communications Systems MR-4 VHF Receiver Racks (144.39 MHz & 145.71 MHz)

Stridsberg Engineering MCA202M (Active Receiver Multi-coupler)

Advanced Receiver Communications Products P144VDG (receiver 24dB/+12dBm GaAsFET preamplifier)

Alpha Delta Communications low loss coax surge protector

 

We are ON-THE-AIR for both 1200 Baud on 144.39 MHz & 9600 Baud on 145.71 MHz as of July 27, 2012 at approximately 07:00 PDT  (1400z)!!!

 

          Click here for our initial 9600 track after departing the I-Gate site.

          I took a little drive from San Francisco through the GG Bridge to Marin over the San Rafael Bridge to Berkeley/Oakland down to Fremont/Milpitas and around to Mountain View to check 9600 coverage of the three 9600 I-Gates.

 

My test station, MTNVW-9 (9600 Baud, 145.71 MHz), is located in Mountain View and will be used for development and testing of new configurations of hardware and software.

 

Special thanks goes to George Lawton, KG6PFG, for setting up the JavAPRSSrvr v3.15b08 APRS-IS software on our Mac Mini under Mac OS X Lion (10.7) for us!

 

Also, thanks goes to Mike Wolters, K6MJW, for assisting in the installation of the Oakland I-Gate station and for setting up a 9600 I-Gate, K6MJW-6, for the South-East Bay 9600 Baud coverage

 

 

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