Topband: 8877 Tube

[ZR]

The only problem with pushing an 8877 or the 3CPX to or over the 4KV limit 
is that it enhances the chance of instability.

Carl
KM1H


----- Original Message ----- 
From: "Paul Christensen" <w9ac at arrl.net>
To: <topband at contesting.com>
Sent: Wednesday, November 14, 2012 7:23 PM
Subject: Re: Topband: 8877 Tube


> Bob,
>
> A non-issue.  Many of us have been running 8877s with Ep of 4KV.  For 
> example, the typical no-load Ep of an Alpha 77Dx/Sx amp is right at the 
> specified limit of 4KV.
>
> Some owners have been converting their 8877 amps over to the 3CPX1500A7 
> which has a much higher rated Ep since it was designed for pulsed service. 
> Unless someone has access to a supply of pulse-rated tubes, I think it's 
> waste of time unless the plate supply voltage is also increased.
>
> Paul, W9AC
>
>
> ----- Original Message ----- 
> From: "Chortek, Robert L" <Robert.Chortek at berliner.com>
> To: <topband at contesting.com>
> Sent: Wednesday, November 14, 2012 6:56 PM
> Subject: Topband: 8877 Tube
>
>
>> Wonder if someone can help with a technical question with the amp I use 
>> on 160 meters.
>>
>> The Spec Sheet for the 8877 tube lists the "Absolute Maximum Plate 
>> Voltage of 4000 Volts" for the tube, and also says in "typical operation" 
>> the plate voltage is between 2700 and 3500 volts. In my amp (Ameritron 
>> AL-1500), the plate voltage is 3750.  My question is - should I be 
>> concerned (it's clearly below the maximum" but above the range that is 
>> considered "typical"?   I just want to be sure I'm not adversely 
>> affecting the useful life of the tube.
>>
>> Any help would be appreciated.
>>
>> 73,
>>
>> Bob/AA6VB
>>
>> _______________________________________________
>> Topband reflector - topband at contesting.com
>
> _______________________________________________
> Topband reflector - topband at contesting.com
>
>
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