Difference between revisions of "VHF Radio (task)"

Latest revision as of 08:57, 28 May 2008

Task: Diagnose and fix or replace Marine VHF Radio System.

Winter 2007 Status

When acquired, Nevermore had a 3-foot long VHF antenna mounted at the top of the her mast. The antenna has no make, model, or identification markings of any kind. The female UHF connector was badly corroded, the antenna wire looks like it's been bent a few times, and the coax cable is badly cracked and disintigrating.

The VHF radio itself is a very old model but seems to receive and transmit.

Spring 2008 Status

Coax Cable

5/25/2008: Two new coax cables have been run through the mast. They are "Marine Grade" RG-8X:

New coax specs:

• 16(19X29) stranded tinned-Cu center conductor
• Foam dielectric
• Type IIA white marine jacket
• Nominal Impedance 50 Ohm
• Velocity of propagation 78%
• Outer diameter .242"
• 98% tinned Cu braid.

Antenna

5/26/2008: A new female UHF connector was installed on the base of the antenna and the antenna was tested at 156.450 MHz at 5 watts of power. The VSWR was measured at 2.5:1. This is too high, so a new marine VHF antenna will be ordered.

5/28/2008: New VHF Antenna ordered: Digital Antenna 200 Series: 222-VW

• 3-foot stainless steel antenna mast
• Quick antenna mast disconnect
• Connector: UHF female (SO239)
• Impedance: 50 ohms
• Max Power: 100 watts
• 3dB gain
• VSWR: < 1.2:1 @ 156.8 MHz

Product Literature: File:DA 3ftVHFAntennas.pdf

Radio

Testing of the radio will commence after the cable and antenna have been replaced and Nevermore is back on the water with her mast upright.