Class C RF Power amps and C4FM P25

[AL7OC]

Am I correct in saying that existing class C power amplifiers for FM repeaters can be used for P25 phase 1 C4FM modulation? I presume that we can replace existing old FM repeaters with dual mode FM/P25 repeaters and utilize existing RF amplifiers. That would making upgrading some amateur repeaters sites to P25 more economically feasible.

It is also correct to say that a linear power amp is needed for P25 phase 2 applications due to the non-constant RF envelope?

Thanks for any insite or advice.

-Pierre

[Wowbagger]

A Class C can do C4FM, as there is no amplitude information.

As for P25 Phase 2: technically, there is no such animal yet (the standards aren't done), but it will be a constant amplitude TDMA system, so again, a class C amp should be OK.

Moto F2 is also constant amplitude TDMA, so again, Class C should be OK.

There are specs in the P25 standard for a non-constant amplitude signaling format (CQPSK), but that is not seeing wide usage, precisely because of the need for linear amps.