Re: [MV] Radio Antenna + Hi-Tension Lines.

Richard Notton (Richard@fv623.demon.co.uk)
Thu, 26 Aug 1999 22:52:21 +0100

-----Original Message-----
From: T. Hintopoulos <hint@northnet.org>
To: Andreas Mehlhorn <a.mehlhorn@t-online.de>; Richard@fv623.demon.co.uk
<Richard@fv623.demon.co.uk>
Cc: mil-veh@skylee.com <mil-veh@skylee.com>
Date: 26 August 1999 13:21
Subject: Re: [MV] Radio Antenna + Hi-Tension Lines.

>
>This "BLOCKING CAPACITOR" I have been reading about, is merely a design
>implementation of the RADIO MANUFACTURER. These folks were not looking at
>Hi-Tension contacts with the antennas. They are looking at making the radios
>work.
>
Any mounted antenna contact with any power line is to be avoided at all costs.

It is not the case that the blocking capacitor is a quick fix to radio
operation.

The typical radio trucks and radios used by British forces were specifically
equipped with blocking capacitors on the carrying frame or used the tuning
variometer as a means of isolating the antenna, you will see this external
component is not used in the static, ground mode of operation in typical
British/Canadian/Australian radios.

Considering the typical low height 440V 50Hz supply in Europe the usual 0.01µF
5KV capacitor looks like just 4ohms at the radio frequency of 4MHz but 318,000
ohm to the power line, thus passing just .0014A with 400V RMS applied and only
.035A at 11KV, this voltage being well above the continuous rating of the
typical device but a second or two of contact would not likely lead to
catastrophic breakdown. It is the nature of capacitors to behave as wattless
resistors with an applied AC voltage.

None of us have any business or need to drive non-serving MV's around with very
large vehicle antennę mounted and in the UK this is traffic offence anyway as
definitive laws exist for vehicle height including any aerials.

Richard
(Southampton UK)
Technical Director - South Coast Comms Ltd
G3ZOE.

===
To unsubscribe from the mil-veh mailing list, send the single word
UNSUBSCRIBE in the body of a message to <mil-veh-request@skylee.com>.