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Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!ihnp4!ihu1h!parnass
From: parnass@ihu1h.UUCP (Bob Parnass, AJ9S)
Newsgroups: net.ham-radio
Subject: Re: FM Optional Add-Ons for HF Receivers
Message-ID: <331@ihu1h.UUCP>
Date: Sun, 2-Sep-84 03:25:47 EDT
Article-I.D.: ihu1h.331
Posted: Sun Sep  2 03:25:47 1984
Date-Received: Mon, 3-Sep-84 10:41:16 EDT
References: <4343@brl-tgr.ARPA>
Organization: AT&T Bell Labs, Naperville, IL
Lines: 37

x
  > 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?

       The FM detector option allows my	 R70  to  detect  NBFM
       signals	within	the 100	KHz - 30 MHz range.  I use the
       FM  detector  mainly  for  cordless  phone   listening,
       although	I used it initially for	monitoring 10 meter FM
       activity.  The FM detector would	be  useful  if	a  VHF
       converter were placed ahead of the R70.

       From reading the	R70  instruction  manual,  it  appears
       that this receiver can be connected to an optional ICOM
       VHF converter in	such a way as to  permit  direct  fre-
       quency readout using the	display	section	of the R70.  I
       haven't yet seen	any ICOM converters offered  for  sale
       in the US.  Maybe European netnews readers can add some
       insight here.

  > 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.

       Yes, the	1947 vintage SX-42 was a  hefty	 toy!	I  too
       wish  Hallicrafters  had	seen fit to permit all band FM
       reception.

-- 
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Bob Parnass,  Bell Telephone Laboratories - ihnp4!ihu1h!parnass - (312)979-5414