Sirio CX455 455-470MHz

[leawoodcops]

I bought Sirio CX455 455-470MHz UHF GMRS Base Antenna
For the house 

3/4 Wave UHF antennas for base station service made of hi-quality materials to get the maximum efficiency and the best performance.

Features:

Base station antenna, Mono-band
Low-gain, Omnidirectional
Protection from static discharges DC-Ground
Made of aluminium alloy 6063 T-83
Electrical Data

Type: 3/4 Wavelength coaxial J-pole
Frequency range 455-475 MHz
SWR less than 1.5: 455-475 MHz
Impedance: 50Ω
Radiation (H-plane): 360° omnidirectional
Radiation (E-plane): beam width -3 dB = 60°
Polarization: linear vertical
Gain: 2dBd - 4.15 dBi
Max. power (CW) : 250 Watts
Grounding protection: All metal part are DC-grounded, the inner conductor shows a DC-short
Connector: N-female

The Carlos Repeater is 27mi from my house 

Height: 170′

And 

Montgomery, TX  repeater 
26mi from my house 

Height 200'

Can I hit iit with this antenna at my house (Navasota) with a 50 watt radio
I have cm400 with n Connectors and the antenna will be about 20 ft in the air and there are some hills 

[WRWE456]

I don't see why not. That is not very far for GMRS as long as there are no hills between your antenna and the repeaters. In fact 5 watts should be enough. I live on a 500 foot hill and with a roof top J-pole can easily reach 30 miles simplex using Wouxun KG-935G+ handheld to the same radio in a mobile set up using a mag mount antenna. That's just furthest we have tested, I think it would reach much further given line of sight conditions.