[Boatanchors] 120 - 240vac and output

[Ron]

Sometimes I sit and read these posts and just shake my head.
The one great thing about the internet is that information can be 
available to a great number of people quickly.  The worst thing is that 
the wrong information can be passed just as easily.

I made no comment during the 2x 4x discussion but now with the 4 times 
your power to double your signal strength .....well ...that's enough.

Primary loss is calculated from I *2 x R not 2x or 4x.  In this case I 
is doubled and 2 squared is 4 so for this specific case , 4x is correct 
......but losses are from the square of the current.  All the 
assumptions so far assume that the secondary side or the high voltage 
transformer acts as a resistive linear load and that is not so.  Take a 
look at the  transfer curves for a 3-500z  and you will see what 
currents it draws 2KV compared to 2.2 or 2.4KV. Current drawn in the 
secondary is reflected to the primary .  When you work this problem , 
you work it from the secondary back to the primary ...not primary to 
secondary.

As far as the 4x power to double signal strength ...it ain't so.  
Doubling signal strength will add 3 dB to your signal strength.  I 
suppose if your signal is 1/2 S unit then adding 3dB would double it but 
when your signal strength is S7 , doubling your power gives you a signal 
of S7.5 as an S unit is 6 dB.
I'll agree about the extra 200 watts ....it won't make a difference.

Come on guys, if your going to post information , remember that a lot of 
fellows will read your stuff and then pass it on.
I can't tell you how many guys will sit and argue a point about some 
information gleaned from some post they read a week or two years ago 
that was just wrong.
---
Ron




Ray Friess wrote:

> What Vic says is true....   AND another thing to remember along with 
> it is that that extra
> 200 watt difference is not going to make a BIT of difference in your 
> signal strength.   The
> receiving station wouldnt be able to tell the difference in your 
> signal if you went from 1000
> watts to 1200 watts.    In fact, the scientific fact is that in order 
> to DOUBLE  your signal
> strength.. you have to FOUR TIMES your power..    so adding an 
> additional 200 watts to a
> 1000 watt signal is not going to make a bit of difference.... even in 
> the worst of QRM or
> band conditions....
>
>
> Vic Rosenthal wrote:
>
>> Gary Schafer wrote:
>>
>>> Think about this for a minute and you should be able to figure it 
>>> out yourself. The only thing that changes in the amp whether it is 
>>> run on 120 or 240 is the primary configuration of the transformer. 
>>> The rest of the amp knows nothing of the difference. Filament 
>>> voltage is the same and plate voltage is the same.
>>>
>>> With a however here, The plate voltage may be a little better 
>>> regulated (may not drop quite as much) because of a little less 
>>> voltage drop on the house wiring on 240 volts. 
>>
>>
>>
>> But keep in mind that the reduction in plate voltage due to primary 
>> voltage drop will be FOUR TIMES greater on 120V than 240V.  The 
>> primary voltage drop will be twice as great, since the current is 
>> double (given the same wire size, etc.). Since the transformer will 
>> need to multiply the voltage 2X more, the drop will be 4X what it 
>> was.  If you have a 120V circuit using no. 8 wire going directly to 
>> the service entrance, the effect will be much smaller; but most 120v 
>> circuits are not like this.
>>
>> This explains why people say they get 1200 watts with 240 V and only 
>> 1000 watts on 120, for example.
>>
>
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