RadioBanter - View Single Post - Phone line as SW antenna [12-Jul-06]

Steve · June 21st 18, 08:26 AM posted to rec.radio.shortwave

(William Mcfadden) writes:

[Last modified 12-Jul-06]

The latest version of this file can be accessed via my web page at:
http://www.rdrop.com/users/billmc

Phone line as SW antenna
Bill McFadden

Changes preceded by "|".

WARNINGS AND DISCLAIMERS

Connecting unapproved devices to phone lines may be illegal in your area.
Telephone lines present a potential shock hazard. Do not use this antenna
for transmitting. Use at your own risk.

INTRODUCTION

This article describes how to use a phone line as a shortwave receiving
antenna. Performance will vary depending on the kind of phone line you
have. Overhead lines usually make okay antennas, while underground lines
| usually don't. Phone lines carrying DSL service may be unsuitable because
| DSL operates over a wide spectrum. A phone line antenna will generally
pick up more power line noise than a dedicated antenna, so don't expect to
| use it for DX work. Nevertheless, I found that it outperformed the
| telescopic whip antennas built into many portables.

A reader sent in this suggestion: If you're concerned about connecting
the phone line directly to the receiver, try wrapping the phone cord
several times around the receiver's telescopic whip antenna instead.
Performance may not be as good as a direct connection, but it will
probably be better than the whip antenna by itself.

Someone else wrote asking about lightning protection. I haven't thought
much about it because thunderstorms are rare in my area. Most phone lines
have lightning arrestors on them where they enter the house, but the
lightning arrestors may pass enough energy during a lightning strike
damage a receiver. My suggestion is to disconnect the antenna when not in
use if you experience frequent thunderstorms.

HOW TO DO IT

The simplest connection is a single capacitor between the phone line and
receiver. The capacitor eliminates all phone line voltages, including
| ringing, so that they will not harm the receiver. The capacitor should
| be rated 250 volts or higher.

you might want to rethink that one. I would go with a working voltage of 500v (480 with diodes). Have yo considered using cat 5 cable. It is usually under the floor boards but most people just stuff the cable in the drop ceilings.

If you are picking up local AM or FM radio stations on the shortwave
bands, it is likely that your receiver is overloaded. Inexpensive and
portable receivers usually lack the filtering needed to eliminate this
interference, but you can make your own filters. Filters can also be
| purchased from shortwave dealers (see below for recommendations).

I couldn't agree with you more. Joe Carr seemed to have a thing for filtering out broadcast stations. Very similiar to what you mention...