ateur ▁services ▁making ▁the ▁qui eter ▁frequencies ▁near ▁the ▁band ▁limits ▁more ▁des irable ▁. ▁Finally , ▁the ▁ 1 2   M Hz ▁split ▁requires ▁high ▁quality ▁and ▁more ▁expensive ▁du plex er ▁devices ▁to ▁isol ate ▁the ▁repe ater ▁receiver ▁from ▁the ▁repe ater ▁transmit ter ▁when ▁sharing ▁a ▁single ▁anten na ▁( as ▁most ▁repe aters ▁do ) ▁whereas ▁the ▁ 2 5   M Hz ▁split ▁provides ▁sufficient ▁frequency ▁separation ▁such ▁that ▁separate ▁anten na ▁for ▁transmit ▁and ▁receive ▁with ▁ 2 0 ▁feet ▁or ▁more ▁of ▁vertical ▁separation ▁often ▁works ▁well ▁and ▁elimin ates ▁the ▁need ▁for ▁expensive ▁du plex ers ▁as ▁long ▁as ▁the ▁repe ater ▁transmit ter ▁is ▁limited ▁to ▁ 1 5 ▁to ▁ 2 0 ▁w att s ▁of ▁output ▁power . ▁ ▁With ▁the ▁explos ion ▁in ▁popular ity ▁of ▁Next el ▁ph ones ▁with ▁a ▁push ▁to ▁talk ▁feature , ▁the ▁market place ▁has ▁seen ▁a ▁flo od ▁of ▁newer ▁ 8 0 0 ▁and ▁ 9 0 0   M Hz ▁commercial ▁mobile ▁rad ios ▁that ▁are ▁designed ▁to ▁the ▁following ▁specific ations : ▁ 8 0 0   M Hz ▁Rad ios : ▁Trans mit : ▁ 8 0 6 ▁- ▁ 8 2 1   M Hz ▁and ▁ 8 5 1 ▁- ▁ 8 7 0   M Hz ▁Rece ive : ▁ 8 5 1 ▁- ▁ 8 7 0   M Hz ▁ 9 0 0   M Hz ▁Rad ios : ▁Trans mit : ▁