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World of Ham Radio 1997
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r7000_20.doc
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1997-02-01
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R7000.20
Part 1/2
A LOW COST PANADAPTOR
FOR THE R-7000
by Bob Parnass, AJ9S
A panadaptor, or spectrum display, is a device which
portrays visually the signals in a part of the radio
spectrum. Panadaptors allow radio listeners to "see"
activity on a portion of band without requiring the
listener to tune the receiver.
They are useful for detecting the presence of spread
spectrum signals or "hidden" signals riding on a sub-
carrier of a main channel. Panadaptors are invaluable
for detecting spurious emissions from transmitters, and
unwanted products caused when 2 or more signals mix.
Panadaptors most often employ a cathode ray tube (CRT)
for the display, and must be connected to the inter-
mediate frequency (IF) amplifier stage of a receiver,
at a point before filtering takes place.
The ICOM R-7000 2-2000 MHz receiver rear panel has a
phono jack for wide band 10.7 MHz IF output. A DC vol-
tage is also present at this connector and is used to
power an ICOM TV accessory.
I've seen mention of 3 panadaptors for the R7000:
1. John Biro's article on retuning a Yaesu YO901
Multiscope panadaptor for 10.7 MHz, restricted
bandwidth use. Selectable bandwidths of 20, 100,
or 200 KHz are available.
2. The Sherwood Communications SCA-7000 signal moni-
tor, priced at $1600, and reviewed in May 1987
"Monitoring Times".3 Bandwidth adjustable from 1
KHz - 1 MHz.
3. The Spectra-Display, priced at $350, which
requires use of an external scope.4 Bandwidth
adjustable from 200 KHz - 10 MHz. Optional
preamplifier required for 12 MHz wide sweep.
CONTINUED IN R7000.21