[BC] BC] Some Input Needed Re: CBS 400, Mosely TFL-280

[KGDNFM1013]

Gates BC-5P - One with a power supply for a 10 KW transmitter on the
Modulator side is what led the FCC to put the 125% limit on positive
modulation.  REEALLY LOUD!

-----Original Message-----
From: broadcast-bounces at radiolists.net
[mailto:broadcast-bounces at radiolists.net] On Behalf Of DANA PUOPOLO
Sent: Tuesday, May 10, 2005 5:33 PM
To: Broadcast Radio Mailing List
Subject: Re: [BC] BC] Some Input Needed Re: CBS 400, Mosely TFL-280


If I recall that Gates rig also had two power supplies - one for RF and
one for the modulator.

That sucker was LOUD! I remember that top 40 WPRO in Providence, RI had
one for it main transmitter. Their 5 kW non d signal at 630 used to be
louder in the Boston suburbs than most of the Boston stations.

-D

------ Original Message ------
Received: Tue, 10 May 2005 04:17:27 PM PDT
From: "Phil Alexander" <dynotherm at earthlink.net>
To: Broadcast Radio Mailing List <broadcast at radiolists.net>
Subject: Re: [BC] BC] Some Input Needed Re: CBS 400, Mosely TFL-280

On 10 May 2005 at 12:16, Scott Bailey wrote:

> Bear in mind, those boxes were built before the early 80's
> term "Super Modulation" came about.  This is were the Commission 
> made it legal for AM's to do 125% positive modulation.  

Just for the sake of accuracy, the FCC didn't start "allowing" it. What
they did was make a rule to put on a limit because many had 
been hitting 150-175% positive since the late 60's. Previously, there
was no rule that prevented anything except exceeding -100% negative
modulation and required at least 80 or 85% (can't recall
which) positive.

In the late 60's Gates made a "special" version of the BC-5P2 
with the 10 kW modulator section of a BC-10P in it. Anyone want 
to guess why? <ggg>

Phil Alexander, CSRE 
Broadcast Engineering Services and Technology 
(a Div. of Advanced Parts Corporation) 
Ph. (317) 335-2065   FAX (317) 335-9037




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