[Boatanchors] 120 - 240vac and output

[Ray Friess]

The 4x power to double signal strength that I was referring to was the 
power output of the
transmitter or linear..       In other words, if I want to double the S 
meter reading on the other
guys receiver from, say, S 4 to about S 9,  and I am running 100 watts 
.... then I generally need
to go to 400 watts to get double that reading on his S meter.     Again, 
increasing my power
output from my linear from 1000 watts up to 1200 watts is not going to 
make me one bit strong
in the other guys receiver or his S meter....   GENERALLY.
     I say generally because if I am running that extra 200 watts into a 
beam with a 9 db gain...
while he wont see a doubling of my signal strength over 1000 watts into 
that same beam, he may
see an S unit difference, which can make the difference between a 
contact or no contact...
especially in a pileup....    Still, to me it wouldnt be worth the worry 
or extra effort to run 220
into my shack just for my linears.   I would, and do, use 115....



Gary Schafer wrote:

> Sometimes it's nice to have information police. It is good for 
> entertainment value if nothing else. :>)
>
> I wonder what the transfer curves look like for 3-500Z's in an SB200? 
> I believe that was the amplifier being discussed. Maybe there are 
> transfer curves for the filaments too? I believe that was being 
> discussed.
>
> The 2X and 4X is a way to get in the ball park with differences as 
> there is 2X the current in a 120 volt circuit from what there is in a 
> 240 volt circuit and there is 2X the voltage step up in the HV 
> transformer in a 120 volt circuit compared to a 240 volt circuit for a 
> given amount of power. If we know the primary voltage drop on the 120 
> volt mains we can figure what it is on 240 volts without too much 
> trouble. Much easier than trying to figure out what the resistance of 
> the mains in your house all the way back to the pole just so you can 
> use I squared R to calculate. Vic is on the mark here.
>
> This was I thought more of a generic discussion on 120 Volts verses 
> 240 volts and how it affects voltage drop. We did not get into 
> transformer losses either which play in the problem.
>
> Part of the discussion was about tube life on 120 verses 240 volts. I 
> assumed that arose from the question of filament voltage-- so my 
> simple answer about that.
>
> As far as signal strength doubling with 4 times the power, that can be 
> correct. It all depends on what your perspective is on what double the 
> signal strength is. If it is one of 2X the power then 3 db of course 
> would be correct. If it is one of 2X the voltage then 6 db or 4X the 
> power would be correct. Without qualifying your statements you are no 
> more correct than Ray was.
>
> It is not always necessary to write reams of information to answer a 
> question. It can always be elaborated to death and no one wants to 
> read it anymore.
>
> However you do add another perspective which I would think is of value 
> too.
>
> Happy thanksgiving,
> Gary K4FMX
>
>
>
> Ron wrote:
>
>> 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.
>>>>
>>>
>>> _______________________________________________
>>> Boatanchors mailing list
>>> Boatanchors at mailman.qth.net
>>> http://mailman.qth.net/mailman/listinfo/boatanchors
>>> ** List Administrator - Duane Fischer, W8DBF/W9WZE **   ** For 
>>> Assistance: dfischer at usol.com **         $$ For vintage radio info, 
>>> see the HCI web site $$      http://www.w9wze.org 
>>
>>
>>
>>
>
>
>
>
>