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Re: RXOffset on a JumboSpot/ChinaSpot

Posted: Sat Jul 27, 2019 12:32 pm
by KE0FHS
FYI, Daniel, K9NPX, has a good article on using MMDVMCAL to get more exact RXOffset (and TXOffset) settings for a DMR radio:
http://www.k9npx.com/2019/02/hotspot-of ... n.html?m=1

Re: RXOffset on a JumboSpot/ChinaSpot

Posted: Fri Aug 30, 2019 9:34 pm
by kd2lh
Be picky about the vendor you're acquiring a Chinese made JumboSpot MMDVM HS Hat from (either simplex or duplex versions).

Be sure that they are using a quality, and preferably US made reference oscillator chip. These tend to be more temperature stable. Look for boards that properly manufactured to comply with the opensource standard board.

Use a consistent packaging, preferably something metal that can passively dissipate heat. I have the tiny Raspberry Pi Zero-W board running both simplex and duplex style MMDVM HS Hat boards in compact metal cases.

I have several of these running, and they all have slightly different MMDVMCAL tested offset frequencies.