[Boatanchors] Short Wave Broadcast Folks:

[Glenn Little]

That 100 KW station is not putting out 100KW transmitter power, but, ERP.
When I was engineer at a TV station, we installed the required 
digital transmitter.
The output tube generated 23KW of RF.
The gain of the antenna, the loss of the 2000 feet of 7 1/4" (or 
close) rigid line and the loss of the combiner gave us an ERP of 630 KW.

For HF, the gain will not be as high, but, the principal is the same.
They have a target audience and will concentrate their energy to that target.

When we had one of the two PAs off line due to a failure, we did get 
a call from the power company because our consumption was below the 
calculated lower threshold.


Also the power to a transmitter site should be 480V 3 phase or 
208/227V 3 phase.
Much more efficient for the rotating components ( blowers, pumps, etc.).

73
Glenn
WB4UIV

At 01:08 PM 4/16/2014, you wrote:
>I can't answer your question directly Dave but Commercial rates are 
>less than Residential.  Here we pay a yearly average of about 7.5 
>cents per KWH. Commercial, depending on the supplier will charge 
>from 5 to 15% less. Another thing about most of the stations to 
>which you refer,  many do not have a 24/7 schedule.
>
>I know of one that is a 50 KW station and they are on the air from 
>about 2-4 pm, depending on the day, until around 11 pm.  About 2 
>years ago they bought a digital transmitter and the engineer friend 
>of mine said it should cut the power bill by about 1/3 or more.  I 
>do not remember what they were paying or the KWH used but it was not 
>all that bad.  Remember, in most cases, they don't have overhead 
>costs of land or building payments to make.  Their only costs are 
>upkeep and maintenance of the building, grounds, tower and transmitter.
>
>Another consideration is they don't have monstrous interest payments 
>on their loans.   In most cases they borrow money from a fund the/a 
>church maintains for such things and the interest is very nominal.
>
>-----Original Message-----
>What's the "60 Hz to HF" power conversion efficiency?
>In other words- How many KiloWatt-hours does it
>take to run a 100KW transmitter for an hour?
>Anyone know?
>
>
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