Local DMR changes, simple UHF solution

  Just a short while ago, I was notified that the main local DMR repeater -- 442.425+ -- has switched networks. Previously, we had an odd situation where the main .425 machine was on the DMR-MARC network, while the low-coverage 442.075+ repeater was on the K4USD network. Now, both repeaters are on the K4USD network. 

  The differences might seem superficial, but this means that all of the code-plugs (and local radios) will need to be modified. Here are the main details: 

• "Local 2" (TS2, TG2) is now TS2, TG 3127 (time slot 2, talkgroup 3127, for those unfamiliar with DMR abbreviations). This links the St. Paul and Minneapolis repeaters into one local "channel", and allows any new repeaters that go on the air to easily link into one common "channel". 

• "TAC 310" is now on timeslot 2, instead of TS1. This makes a lot more sense. TAC 310 is the "channel" that users are supposed to QSY to for extended conversations, rather than "tying up" the major talkgroups. "World Wide", for example, has a limit of two-minute QSOs. With TAC 310 on the same slot as these major talk-groups, switching to TAC 310 just gets you wiped out by any traffic whatsoever on the most popular "channels". The down-side is that using TAC 310 wipes out the Local "channel", but that's much more preferable considering the low level of local traffic. 

It was pretty easy for me to make these changes to my radio, but I have a Connect Systems CS-700. Those with Motorola radios (using proprietary and licensed software) might have a more difficult time making these simple changes. Your best option is to contact KE0NA (Dave), as he has the latest software and is quite willing to help get people on the air. 

Though this change is a bit inconvenient, it's well worth it and will make future expansion as painless as possible. 

On a personal note, I made an upgrade to my DMR station. Up until now, I've had to operate out of my living room while on DMR to take advantage of the exterior antenna. With just an HT running 4W, reaching the repeater at the East Bank campus has been "hit or miss" using the duck. Using a mobile whip in my study has worked fairly well, but I've still had others report intermittent packet loss (where the signal becomes garbled) when using this arrangement, especially when there is activity on the local VHF .850 repeater. One of the remote receive sites for the .850 is located in close proximity to the DMR repeater, and it can slightly "de-sense" the 442.425 receiver when the received signal is weak. Four watts running out of an indoor mobile whip in Plymouth qualifies as a 'weak' signal. 

What I did to change this was to buy a cheap ($20) tripod used to mount photographic lights, and attaching a simple three-element UHF Yagi to it. A test with NH7CY (Jason) this afternoon proved that the solution works, even while there's activity on the .850 machine. 

On the plus side, I can also use this for my 40W TYT UHF mobile in my study, allowing me to reach other UHF repeaters (and GMRS repeaters) much better while working at my computer. 

Certainly, a three-element UHF Yagi is pretty easy to make and to customise for your own situation, but I already had this one sitting around. Besides being a nice and effective solution for apartment-dwellers, it easily folds up for portable field work on UHF and can operate in either horizontal or vertical polarisation. Since UHF has much better building penetration than VHF, almost anyone can copy this solution to greatly improve their HT range on UHF without using an outdoor antenna.