[Milsurplus] Radio pic and early FM

[Mike Feher]

I agree, Kurt. I cannot see that being the reason for the military not using it back then. I got my ticket in '63 and started on 2M FM around '66. Used some modified GE units first then went solid state. Never experienced any so called "captured" effect.  73 - Mike 

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ 07731
908-902-3831

-----Original Message-----
From: milsurplus-bounces at mailman.qth.net <milsurplus-bounces at mailman.qth.net> On Behalf Of Facility 406
Sent: Saturday, April 19, 2025 3:37 PM
To: milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] Radio pic and early FM

> The aviation industry deliberately passed on FM because to the 
> "capture effect."  An FM set, stuck on transmit, can block an entire channel.
> This is bad news when your up in the air covering a large area.  On AM 
> you at least have a chance of hearing another weaker station.

I've heard this all my life.

And, living in Nevada, where stations are spread out, it's barely a thing.

My personal observations, across 2+ decades, many FM receivers/transceivers, it works like AM.  Hear one, hear two, or more, but, also like AM, when closer to a stronger one, the stronger seems to take over.

I can personally attest, for the FM broadcast band, 2m, and 440 MHz, there is little to no capture affect, just one station stronger than the other, and I observe it several times per week.

I also monitor airband comms, almost daily.  One can hear one, two, three, with varying levels of interference to each other, to completely blocking.  So, in this sense, AM will also "capture".

AM, FM, they work the same, strongest "captures", modulation doesn't matter.

Perhaps the "capture" thing was based on a particular model receiver, under certain conditions, and the notion stuck?

I tune AM/FM just the same, reception is just the same, and being in a sparse/rural area, it's a good thing, as I often listen to both AM and FM in the boonies, and on the fringe of reception.

Kurt



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