[AMRadio] Source Broadcast Xmtrs

Mon Jun 13 16:02:28 EDT 2011

The MBL-1 was targeted to shortwave broadcasting. I put the beta on a 
modified Marconi 250 Kw transmitter owned by the BBC. It had some very 
aggressive tilt and overshoot compensation capability. It could be made 
to be very loud. It also had an adjustment to keep low frequencies out 
of the clipper. The one important feature was that it moved any audio 
frequency shaping to the limiter's input. The transmitter would ideally 
be flat from below 1 hertz to at least 3 times the upper input frequency.

Two other hot boxes are the Orban shortwave Optimod (there has to be a 
ton of those surplus)and the hard to find Gregg Labs processor.

On 6/13/11 3:48 PM, Dennis Gilliam wrote:
> Indeed, and CRL was made just down the street from the station I retired
> from.  They made a great limiter for AM, and never forget the DAP-310 from
> KO6NM, either.
>
> 73DG
>
> On Mon, Jun 13, 2011 at 12:39 PM, W2XJ<w2xj at nyc.rr.com>  wrote:
>
>> Good low frequency response is important if broadcast style processing
>> is used. The major name processors from the 80s and on used LF
>> compensation to adjust tilt on clipped peaks and increased to amount of
>> usable modulation. Those equalizers were designed to match the typical
>> plate mod transmitters around at the time which went down to somewhere
>> between 30 and 50 hertz. A 300 hertz cut off is far from adequate when a
>> good processor is used before the transmitters.  If you want a screaming
>> processor, try to find a CRL MBL-1.
>>
>> On 6/13/11 2:47 PM, Dennis Gilliam wrote:
>>> I suppose it all boils down to what you want it to sound like, and the
>>> 'wick' behind it.
>>>
>>> Telephone audio is 300-3000 HZ more or less, done that way to get through
>>> without any frills.
>>>
>>> Lots of military and ham rigs use that paradigm so as not to use too much
>>> (pick one or more) weight, power, bandwidth eTc.
>>>
>>> It gets the job done.  So does riding a bus vs driving a nice car.
>>>
>>> BC audio is 50 to 10K or more usually, and needs a healthy carrier behind
>> it
>>> to get through.
>>>
>>> Run what you brung, conditions and the other guys' RX will set the scale
>>> anyway.
>>>
>>> 73DG
>>>
>>>
>>>
>>> On Mon, Jun 13, 2011 at 11:37 AM, Ron Youvan<ka4inm at tampabay.rr.com>
>>   wrote:
>>>> rbethman wrote:
>>>>
>>>>> The frequency response is MORE than adequate for the human voice.
>>>>> The audio input transformer is rated from 400cps to 3500cps.
>>>>     That depends on whether the audio is limited to 400cps to 3500cps or
>>>> flat from 400cps to 3500cps.
>>>>
>>>>     As much as anything else the voice sound is controlled by the
>> microphone.
>>>> --
>>>>      Ron  KA4INM -   Every HAM should have at least one desk MIC,
>>>>                      it's the perfect place to hang the cans when
>>>>                      CW is "arm chair copy."
>>>> ______________________________________________________________
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