RXOffset on a JumboSpot/ChinaSpot

MMDVM_HS Hat hardware
User avatar
KE0FHS
Posts: 1122
Joined: Wed Apr 11, 2018 8:40 pm
Location: Colorado, USA
Contact:

Re: RXOffset on a JumboSpot/ChinaSpot

Post 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
73, Toshen, KE0FHS
Playing with Pi-Star (unofficial notes about setting up and using Pi-Star):
https://amateurradionotes.com/pi-star.htm
User avatar
kd2lh
Posts: 33
Joined: Thu Aug 22, 2019 3:26 pm

Re: RXOffset on a JumboSpot/ChinaSpot

Post 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.
Post Reply