5 Watts & 2 Time Slots or 10 Watts & 1 Time Slot

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drey7

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Hello. I am looking at some radios --- TYT MD-390 and TYT MD-398. The MD-390 is 5 watts with 2 time slots, and the MD-398 is 10 watts with 1 time slot. Does anyone have any thoughts as to which might be a better choice and why?

I know the time slots have affect communication through repeaters, but I don't really understand what effect having 2 time slots vs 1 time slot has on ones ability to communicate.

Thank you.
 

N4KVE

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With 2 time slots, there can be 2 conversations happening on 1 freq at any given time. One on TS1, & the other on TS2. That's the beauto of DMR. So if you live in North America,, you would get the radio that uses 2 time slots. Don't know about other countries. That TS 1 only thing was the problem with that new Baofeng $70 dual band DMR radio.
 

drey7

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Thank you. I guess that is where I am struggling. I understand... I think.... that the time slots is the sharing of the frequency... and you must pick a time slot to 'join' one conversation or the other, right?

So... if I am only going to have 1 conversation, why would I need 2 timeslots? Does that mean a unit with 1 timeslot could only hear 1 of the conversations and would never know about the other one? Do the units that only have 1 timeslot understand 2 timeslots and only use the first one... or do the conversations on those units use up both time slots because they 'don't know any better'?

I assume that means radio to radio wouldn't really be affected.... but if you wanted to use a repeater... it would be better to have a radio that understood how to (and used) 2 timeslots?
 

N4KVE

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Thank you. I guess that is where I am struggling. I understand... I think.... that the time slots is the sharing of the frequency... and you must pick a time slot to 'join' one conversation or the other, right?

So... if I am only going to have 1 conversation, why would I need 2 timeslots? Does that mean a unit with 1 timeslot could only hear 1 of the conversations and would never know about the other one? Do the units that only have 1 timeslot understand 2 timeslots and only use the first one... or do the conversations on those units use up both time slots because they 'don't know any better'?

I assume that means radio to radio wouldn't really be affected.... but if you wanted to use a repeater... it would be better to have a radio that understood how to (and used) 2 timeslots?
While someone else is having a conversation on TS1, you could be talking to someone on TS2. This is why you would want a radio that does both time slots. DMR radios that only do 1 time slot shouldn't be imported into the USA.
 

jonwienke

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With the ability to only use one slot you would miss out on half of the channels. You might be able to use local and not international or vice versa.
Actually, radios that can't handle dual timeslots won't talk to repeaters at all. They can only talk to other single-timeslot radios in simplex mode, and waste about 50% of the battery power when transmitting. The DMR digital modulation and voice encoding scheme only requires the transmitter to run 50% of the time--33 milliseconds on, and then 33 milliseconds off. This allows 2 radios to transmit on the same frequency; one transmits for 33 milliseconds, then it shuts off and the other radio transmits for 33 milliseconds. The MD-380 and MD-390 work this way, so they can talk to repeaters, and they use about 50% of the battery power in digital mode they do in analog FM mode.

The MD-398 is a stupid design; it transmits continuously. Instead of shutting down after 33 milliseconds and waiting 33 milliseconds before transmitting again, it rebroadcasts the first 33 milliseconds' data in the second 33 millisecond time slot, which wastes battery power and guarantees repeater incompatibility because the handheld has to stop transmitting in order to sync with the repeater and receive signaling, status, and control data from the repeater. The Baofeng DM-5R does the same thing, so I wouldn't recommend either radio.

If you get the MD-380 or MD-390, you get a radio that complies with DMR standards and does everything except trunking, and uses battery power much more efficiently.

Also, going over 5-7 watts with a handheld is unwise due to RF exposure.
 

KE4NYV

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"Single timeslot" radios are only Tier I DMR. They are essentially useless unless you're talking to another Tier I user directly. Just because it says it has timeslot 1, that doesn't mean you can talk on a repeater on just timeslot 1. Tier I does not support repeater operation at all.
 
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