[BC] Modulation Monitors...

[Robert Meuser]

Must disagree, Burt.

The FCC uses a scope for both AM and FM modulation measurements. The 
original discussion was limited to AM operation where a scope is the 
best way to check modulation. I agree that positive modulation  is a 
little more difficult to observe but then I know of no station that 
observes the positive modulation rule.  Harold stated a while back on 
one of the lists that from his records no station has ever been cited 
for positive over mod.  I know of major stations in the top groups that 
will not accept equipment that does not do at least 145% positive mod. I 
have never accepted at TX that does less than 165% positive mod and have 
never run a TX at anything less than 150%. My antenna systems are 
contractually speced for 200% mod with continuous tone bursts.

R


Burt I. Weiner wrote:

> Any station that does not have a properly working modulation monitor 
> for their transmitter/s is fooling themselves and whoever is 
> responsible should have their head examined.  If you think the 
> bargraphs on the front of the transmitter are going to tell you what's 
> happening, you're wrong.  A scope is fine to a point but it won't tell 
> you if you're modulating 115, 120 or 125 percent positive peaks under 
> dynamic program conditions.  You cannot resolve modulation close 
> enough with a scope under program conditions.
>
> Burt
>
> At 01:11 PM 7/18/2006, you wrote:
>
>> From: Alan Alsobrook <radiotech at bellsouth.net>
>> Subject: Re: [BC] Modualtion Monitors (do we need them?)
>> To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
>> Message-ID: <44BD25FD.7010800 at bellsouth.net>
>> Content-Type: text/plain; charset=us-ascii; format=flowed
>>
>> You don't need a "modulation monitor" but you do need to have a method
>> of determining your modulation.
>>
>> Modern processors do a good job of keeping the modulation consistent and
>> limiting at their set point, but you need something to determine that
>> you have them set correctly. If caught in violation, without a means to
>> determine modulation not only could you be written up for the over
>> modulation, you can add unable to determine modulation. 73.1350(c)
>>
>> Bailey, Scott wrote:
>> > To the group:
>> >
>> >     How many of you, (excluding the big Class A stations) that take 
>> care
>> > of stand alone AM's, have or use a modulation monitor?  In a previous
>> > conversation with Dennis at KKTY on this list, he made mention he
>> > doesn't use one. He relies on his Orban 9300 to take care of not over
>> > modulating.
>>
>> -- 
>> Alan Alsobrook CSRE AMD CBNT
>> St. Augustine Fl. 32086 904-829-8885
>> aalso at Bellsouth.net
>
>
> Burt I. Weiner Associates
> Broadcast Technical Services
> Glendale, California  U.S.A.
> biwa at earthlink.net
> K6OQK
>
> _______________________________________________
>
> Do you have a BDR? http://www.oldradio.com/bdr.htm
>