AM-47.80mHz NAtO-CombatScene-Philadelphia

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catching this strange Humm over the AM in philly,,on a NATO freq ,,
anyone else can confirm,know what it may be?
never got this before,even yesterday..

freq-
47.80000AM
no tone-
 

prcguy

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Are you sure its AM? Modern mil radios cannot even go AM in VHF low band except for a few multiband units. I would expect narrowband FM on that freq (5 to 8KHz is the mil new spec) with a loud 150Hz tone which will make a heck of a humm in AM mode.
prcguy

catching this strange Humm over the AM in philly,,on a NATO freq ,,
anyone else can confirm,know what it may be?
never got this before,even yesterday..

freq-
47.80000AM
no tone-
 

mancow

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So, what is the proper bandwidth? I see 5, 6 and 8 in the multiband radios we are familiar with but never knew which one is the default Mil FM standard.


Are you sure its AM? Modern mil radios cannot even go AM in VHF low band except for a few multiband units. I would expect narrowband FM on that freq (5 to 8KHz is the mil new spec) with a loud 150Hz tone which will make a heck of a humm in AM mode.
prcguy
 

prcguy

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5KHz for compatibility with commercial/ham gear and 8KHz with 150Hz tone for mil gear.

Older mil FM equipment from the Korean war was 15 to 25KHz deviation and sometimes more. PRC-25s, 77s and 524s from the Vietnam era were around 12 to 15KHz dev and sometime around the 1980s they started to cut back the dev to about 8KHz for FM VHF low band radios.
prcguy

So, what is the proper bandwidth? I see 5, 6 and 8 in the multiband radios we are familiar with but never knew which one is the default Mil FM standard.
 

mancow

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So that explains why the kids I heard playing on a couple of PRC77s were just beating the hell out of the receiver in this thing (5800)
 

Hooligan

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I recall bandwidth being 30kHz, & they couldn't really start altering it until *all* fielded radios were compatible. I didn't even know it changed from 30 for SC use.
 

prcguy

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Not only will the deviation on a PRC-77 go beyond the passband of a narrow band receiver, the 150Hz tone is set around 3KHz which is almost full voice deviation for a narrow band rig.
prcguy

So that explains why the kids I heard playing on a couple of PRC77s were just beating the hell out of the receiver in this thing (5800)
 
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I prog'd the freq and tagged it,think i got it from the wiki,,maybe from Mt,,not quite sure,,

as far as AM-FM,,i had it set to auto,so just going by what the LCD told me,,
like i said,,not sure what it was,probably somthing benign,but i fig'd id fly i kite
and see if lightning struck..

i only posted because it was a strange humm-buzz with some blips at reg intervals
was curious and if anyne else picked it up..
 
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