Topband: Silent Feedline for RX antennas

[W0UN--John Brosnahan]

RG-22/U,   RG-22A/U,   RG-22B/U are the designators for the
Twinax cable that looks like RG-213 (RG-8).   It is 95 ohms
impedance.  Proper connectors are harder to find surplus
than the coax--but can be bought for $20+ if I recall properly.

RG-22B/U is the non-contaminating jacket version.   If I were
buying surplus cable I would insist on this version.

I used a few thousand feed for low noise in an HF ionospheric
sounding interferometer that I build at Arecibo about 12 years ago.

The receive array was some very short (crossed) dipoles, close to
the ground.  So they were very inefficient.   I went to the balanced
RG-22B/U to keep the noise floor as low as possible because of the
proximity of all of the computers and transmit equipment.

This was not built at the dish, but rather at their HF heater facility
at Isolote, which was destroyed in floods a few years ago when
the pumps that kept the region above the water table failed.

73--John    W0UN