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Re: [Amps] AL-80B transformer tap

Subject: Re: [Amps] AL-80B transformer tap
Date: Mon, 23 Jul 2007 02:52:23 EDT
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In a message dated 7/23/2007 2:41:12 A.M. Eastern Daylight Time, writes:

So what  do you guys think, is the 245VAC tap the way
to go? Also keep in mind that  I have only done three
readings, the line voltage could drop closer to  240
under further grid demand. It was suggested to me by
KM1H to watch  the effects on the tube filament
voltage, but I do need a starting point,  and I am
quiet willing to admit that I lack experience. 

James - AD1L

Hi James,  You are VERY fortunate to have such "nice" line  voltage.  But to 
the point, the most important thing here is the filament  voltage.  You want 
your filament voltage to be 5 volts.  Eimac will  tolerate 5.25 volts, but you 
will get better tube life at 4.8 to 5 volts.   The thing to do is to actually 
measure your filament voltage using the 245 tap  and see what it is.  If it's 
high go to the 250 tap.  If it is spec,  you can stay with 245 tap.  The tube 
must be in the socket when measuring  and measure right at the filament pins 
of the tube socket.  As far as HV  goes, any tap is OK for that.  The lower the 
tap, the higher your plate  voltage will be.  You won't notice a difference 
of "on the air" signal but  you will get a tad bit more power out on a lower 
tap.  The filament voltage  will dictate. 73 Lou

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