[AMRadio] Source Broadcast Xmtrs

[Bob Macklin]

Bandwidth for communications quality AM is +/- 3KC. Commercial AM broadcast 
transmitters have more bandwidth than this. Close to +/- 5KC.

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message ----- 
From: "Bernie Doran" <qedconsultants at embarqmail.com>
To: <ka4inm at tampabay.rr.com>; "Discussion of AM Radio in the Amateur 
Service" <amradio at mailman.qth.net>
Sent: Saturday, June 11, 2011 4:48 PM
Subject: Re: [AMRadio] Source Broadcast Xmtrs


>" big iron limits the fidelity in ways that a rice box doesn't" what an
> interesting view, rice boxes cut off the lows and also cut off the mid and
> highs  300 to 2100 seems typical, so I guess if the definition of fidelity
> is 300 to 2100 then perhaps the big iron does limit fidelity.  of course 
> now
> someone will chip up and say we can only use 3 kc bandwidth, or that we 
> need
> to conserve bandwidth, does it wear out after a period of time?
> ----- Original Message ----- 
> From: "Ron Youvan" <ka4inm at tampabay.rr.com>
> To: "Discussion of AM Radio in the Amateur Service"
> <amradio at mailman.qth.net>
> Sent: Saturday, June 11, 2011 6:32 PM
> Subject: Re: [AMRadio] Source Broadcast Xmtrs
>
>
>> John Lyles wrote:
>>
>>> Alas, as Don Chester replied, 1 kW and smaller AM tube rigs are getting
>>> scarce. However, small mom-and-pop stations are still there on local
>>> channels in smaller communities, barely hanging on, with tube
>>> transmitters and backups. If you live in such areas, such as I do in
>>> northern New Mexico, recommend getting to know the management, or the
>>> local contract engineers who take care of these. Nowadays, one engineer
>>> could maintain 5-10 stations. Sometimes all the engineers are friendly
>>> enough to invite you to their get-togethers, such as Friday lunch at a
>>> cafe.
>>
>>   As a broadcaster of over 48 years experience I don't understand the
>> fascination with plate
>> modulated AM transmitters.
>>   First I was a HAM wannabee when AM was king and the heterodynes were
>> both hideous and everywhere.
>> Frequently unavoidable on just about every QSO. *
>>   Secondly the "big iron" that everyone covets limits the fidelity in 
>> ways
>> that a rice box followed
>> by a one kW linear amplifier doesn't.
>>   Thirdly, USA HAMS are limited to 375 Watts unmodulated carrier, (1.5 kW
>> P-P) a one kW AM
>> transmitter can produce one thousand Watts of unmodulated carrier.  (so
>> you need to cut it back)
>> * everyone disappeared when SSB took over (what ever that is) as did the
>> heterodynes when I got a BFO
>>   Early commercial and locally built AM transmitters were often a low
>> power modulated transmitter**
>> followed by a linear amplifier
>> ** frequently using Heising modulation
>>
>>   Ron KA4INM  73
>>
>>> I have gotten two of my rigs from the AM forum listings over the years,
>>> and one from a local station that wanted it moved out quickly. They are
>>> now relocating their TX to a new tower, so they called again last
>>> Friday,"help move this thing". A little Harris solid state, an old solid
>>> state MW1 Gates, and a rare and horrible ITA1000. A ham friend is
>>> helping move the transmitter site, hopefully he will get the ITA. The
>>> others will stay in service on BC Band. So by helping them out,
>>> transmitter gets recycled.
>>
>>
>> -- 
>>    Ron  KA4INM - You can't fool me ...
>>                       ... I'm a moron.
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