[Amps] 3-1000Z Filament Voltage Question

Tomm Aldridge KD7QAE at ARRL.NET
Sun Feb 20 11:06:06 EST 2005


'cept by then all broadcast stations will be in orbit...

N7HIY wrote:
> take a 220v line measurement twice a day for a week and record at peak 
> demand and low demand periods...look at max and min...may surprise 
> you..definitely do not want to go high on the filament voltage for the price 
> of a 3-1000 and avail...is your plate trans. tapped es will your amp hv 
> design handle a higher plate voltage?
> also may want to consider inrush current protection on the 3-1000z 
> filament...well worth the time es few parts..hi pwr glass envelope RF tube 
> production will end in 5-10 years even in China es Russia...then we will be 
> picking thru the dumpsters behind old broadcast stations
> 
> Cliff  N7HIY
> 
> ----- Original Message ----- 
> From: "R.Measures" <r at somis.org>
> To: <garyschafer at comcast.net>
> Cc: <amps at contesting.com>; <dajs at accnorwalk.com>
> Sent: Sunday, February 20, 2005 2:12 AM
> Subject: Re: [Amps] 3-1000Z Filament Voltage Question
> 
> 
> 
>>Possibly, but 7.08v is definitely low for a 7.5v filament.
>>
>>On Feb 19, 2005, at 11:14 AM, Gary Schafer wrote:
>>
>>
>>>Your meter calibration is probably off that far unless you have a very
>>>good one.
>>>
>>>73
>>>Gary K4FMX
>>>
>>>Dennis Sokol wrote:
>>>
>>>>I have a BTI LK-2000 using a 3-1000Z operating on 160. I can get 1250
>>>>watts out with 2700 volts and 750 ma key down. The tube seems to be
>>>>limited in current draw. I have seen more power out at a different
>>>>QTH with higher line voltage.
>>>>
>>>>I have measured the filament voltage at full load to be 7.08 volts.
>>>>This is a bit low from the spec of 7.13 to 7.87 volts. Is the low
>>>>filament voltage a possible cause of reduced power out?
>>>>
>>>>There is a 208 volt tap on the filament xformer but I would have to
>>>>put in a dropping resistor in the primary to bring the voltage down
>>>>to 7.5 volts.  Is it worth the effort? Am I hurting the tube with the
>>>>lower filament voltage or am I extending the life?
>>>>
>>>>Thanks and 73,
>>>>Dennis W0JX Milan, OH
>>>>_______________________________________________
>>>>Amps mailing list
>>>>Amps at contesting.com
>>>>http://lists.contesting.com/mailman/listinfo/amps
>>>>
>>>>
>>>
>>>
>>>
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>>>
>>>
>>
>>Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>>
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>>http://lists.contesting.com/mailman/listinfo/amps
>>
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