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Path: utzoo!watmath!clyde!burl!mgnetp!ihnp4!drutx!houxe!hogpc!houti!ariel!vax135!cornell!uw-beaver!tektronix!hplabs!hao!seismo!brl-tgr!wmartin
From: wmartin@brl-tgr.UUCP
Newsgroups: net.ham-radio
Subject: FM Optional Add-Ons for HF Receivers
Message-ID: <4343@brl-tgr.ARPA>
Date: Thu, 30-Aug-84 11:19:07 EDT
Article-I.D.: brl-tgr.4343
Posted: Thu Aug 30 11:19:07 1984
Date-Received: Sat, 1-Sep-84 13:07:28 EDT
Organization: Ballistics Research Lab
Lines: 22

Many HF receivers, such as the Icom R-70 and R-71, have an extra-cost option
of an FM detector mode. This is intended, I believe, for use in receiving
narrow-band FM used in certain ham bands. I am under the impression that
those bands are all above 20 MHz. Does anyone know if these FM options are
so contructed so as to only operate in this higher portion of the HF
spectrum? Or will they function no matter what frequency the receiver is
tuned to?

I ask this because older tube receivers, such as my old Hallicrafters
SX-42, which cover from medium wave up to 108 MHz, have FM modes which
only function in the higher bandswitch position(s), not at all
frequencies. I discovered this when trying to use this receiver toto
tune cordless phones using FM in the 1600-1800 kHz range. (I know I
can tune in AM using slope detection; I just wanted to use the for-real
FM mode if I could.) Since these new-style receivers have no "bandswitch"
as such (but maybe a MHz-selection mechanism), it would seem that the
FM option could be turned on independent of the tuned frequency. I
would appreciate confirmation of this supposition.

Regards, Will Martin

seismo!brl-bmd!wmartin     or     wmartin@almsa-1