[OZAPRS] Maxon DM-2550 and TinyTrak3

Dion Bramich vk7ybi at yahoo.com.au
Mon May 28 20:27:59 EST 2007

The CD line doubles as a power save input I think, so if theres something

happening there its probably putting the radio to sleep.  I have 2  
trackers built on Maxon modules and TT3s with CD, with no problems.


On Mon, 28 May 2007 17:55:21 +1000, Michael Carey  
<michaelcarey at internode.on.net> wrote:

> Hi Everybody,
> I'm turning a TinyTrak3, Maxon DM-2550 and a Garmin GPS-15 into a
> transportable APRS tracker. So far my plan is to jam the whole lot, plus
> a small gel battery into a small Pelican case.
> I've made up a small LM-317 based regulator for the DM-2550, providing
> the transceiver with 10V. I also planned on using the carrier detect
> output from the DM-2550 to stop the TinyTrak3 from stomping on other
> transmissions.
> It's about here I have come across something weird... I'm powering the
> TinyTrak3 from the same 10V regulated supply as the DM-2550. If I apply
> power to the regulator (connected to both the DM-2550 and the TinyTrak3)
> the DM-2550 goes into a non-operational state, no transmit, no receive.
> I originally thought it was the fault of the DM-2550 and Garry was happy
> to swap it over, but it's the same story with the replacement.
> I've got a WXtrak/DM-2550 combo in a half built Peet Bros based weather
> station which seems to exhibit the same problem, but _only_ after I
> connected the CD line of the TinyTrak3 to the DM-2550. Without the CD
> line connected, there is no problem.
> If I unplug the DM-2550 and connect it up again, things are OK and will
> be as long as the power supply in maintained. And here is the weird
> part... if I run the combination from a 9.6V NiCd battery pack, I have
> no problems. If I power the TinyTrak3 from a seperate supply (prior to
> the regulator circuit for instance), it's OK as well.
> Has anyone in the list seen this problem with the DM-2550 before?
> Regards,
> Michael.
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