wmartin@brl-tgr.UUCP (08/30/84)
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
parnass@ihu1h.UUCP (Bob Parnass, AJ9S) (09/02/84)
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. -- ***NOTE NEW ADDRESS*** =============================================================================== Bob Parnass, Bell Telephone Laboratories - ihnp4!ihu1h!parnass - (312)979-5414
mikey@trsvax.UUCP (09/07/84)
#R:brl-tgr:-434300:trsvax:52800032:000:393 trsvax!mikey Sep 7 09:31:00 1984 The cordless phones that I have experienced were FM only in the VHF low band (49 Mhz). The 1600-1800 link were all AM. The new phones that are advertised as all FM use new frequencies recently allocated at 49 Mhz to get FM both ways. BTW, the phones that used 1600-1800 were carrier current AM for the base to handset and FM VHF for handset to base. Mike Yetsko KA5MJQ mikey at trsvax