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Converting a D-Star Hotspot to a Full Duplex Repeater

If you have a gmsk modem and put up a D-Star Compatible Hotspot, it is quite easy to convert this simplex system to a full duplex repeater that supports DPlus linking to other repeaters, reflectors and often to Hotspots, DVAPs and DV Dongles.  With other software, this same equipment can become an ICOM G2-compatible repeater that supports Callsign Routing.

Here's all you need:

Details:

Caution:  Inexpensive duplexers normally provide about 75 db isolation between Rx and Tx.  When running 50 watts or less, this is probably ok.  This type of duplexer requires a split of at least 3.5 mHz for VHF, or 5.0 mHz for UHF.  If you are hoping to get your repeater coordinated in the US, this split may or may not be acceptable to the coordinators.

If your repeater will be located at a high-RF location, for example on a commercial repeater tower, an inexpensive duplexer will not work for you.  You will need a high quality duplexer with 100 db or more isolation and possibly other equipment.  You can get lots of info from the internet, such as Repeater-Builder website.

My software for now is DVAR Hot Spot, so I needed to load Windows to my new PC, and I wanted a slimmed-down Windows installation.  In addition, since Compact Flash cards have a lifetime limit in write operations, I wanted Windows to avoid all hard disk writes during normal operation.  This page explains how I did that.

Configuration  

Step 1 - Connect the cable and configure the radios
  • Connect the female connector to the Hotspot cable from the gmsk node adapter board.  Be sure to plug the male cable marked Tx into the transmit radio, and the one marked Rx into the receive radio.
  • Tune the Rx and Tx radios to their respective frequencies, and depending on radio, set packet mode, etc.  If using a radio that's never been in Hotspot or repeater service, check the Radio Files folder in the Files section of the gmsk_dv_node Yahoo Group website for advice on how to configure.
Step 2 - Run NAWinCFG to configure for Full Duplex
Step 3 - Run NAWinTest
Step 4 - Change the DVAR Hot Spot settings to Repeater mode
Step 5 - Test it out
That's it!

Note:  I recommend you set DVAR's Callsign Server Settings to DUTCH*Star NLroot, so your repeater's callsign will show up on other DVAR hotspots who might want to connect or link directly to your repeater.  There is also a trick that DVAP and Dongle owners can do so they will also see HotSpots and DVAR Repeaters.  This trick is documented at DUTCH*Star DPNS  (click on the DPNS button).

My DPlus Repeater consists of:

Total incremental cost: $390 (new PC) or $210 (using spare PC) - in both cases using spare analog radios and an existing antenna and coax.

    Jim - K6JM

D-Star® is a registered trademark used for communication equipment (repeaters and transceivers) for amateur radio communications, and owned by Icom Incorporated.

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