[ARC5] BC sets and others.

[Geoff]

----- Original Message ----- 
From: "Rob Atkinson" <ranchorobbo at gmail.com>
To: "Geoff" <geoffrey at jeremy.mv.com>
Cc: "Robert Eleazer" <releazer at earthlink.net>; "ARC-5 List" 
<arc5 at mailman.qth.net>
Sent: Thursday, January 23, 2014 6:13 AM
Subject: Re: [ARC5] BC sets and others.


> On Wed, Jan 22, 2014 at 3:15 PM, Geoff <geoffrey at jeremy.mv.com> wrote:
>> I believe that is still inaccurate, but I invite you to do the legwork; 
>> Im
>> kind of busy these days getting customer repairs out the door.
>>
>> It is my understanding that the 10.2 kHz is the total audio bandwidth and
>> not each sideband.
>
> It is the total audio bandwidth but a double sideband AM signal has
> two sidebands each carrying the full audio response so the occupied
> bandwidth before any attenuation kicks in is twice the audio response
> upper limit.

** Im rather aware of how AM works since I use it almost daily but Im still 
under the impression that pre-emphasis was added to boost treble at the 
transmitter to compensate for the rolloff above 5 KHz.

Consumer grade receivers seem to have plenty of treble but lack the bass due 
to small speakers and insufficient inductance in audio transformers when 
used. Listening to a female on those sets can be downright painful (-;

Im still looking for that FCC citation.

>
>> In any case many antenna systems do not have much beyond a 10KHz BW, Ive
>> been at several stations and can listen to what comes out of the TX and 
>> also
>> what actually gets broadcast. The chopped sidebands are very apparent.
>
> Indeed, achieving a flat vswr curve over 20 kc is not easy especially
> with a phased system of two or more towers.
>
> 73
> Rob
> K5UJ


** It is not easy with a single short tower either especially as the 
frequency goes down and a 1/4 wave gets mighty tall.
Antenna network desigs are available that can even chop sidebands at the 
high end on a single full size tower.

Carl

>
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