[Amps] Aplha 91b

[Fortra]

Hi Rich,

the Alpha 91b being produced in Bulgaria used GU74B or 4cx800.
What are the contents and materials used in Russian tubes, i do not know!

Regards,

Nermin S58DX
----- Original Message ----- 
From: "R.Measures" <r at somis.org>
To: "Helmut (DF7ZS)" <hm at df7zs.de>
Cc: <amps at contesting.com>
Sent: Monday, January 10, 2005 10:38 AM
Subject: Re: [Amps] Aplha 91b


> 
> On Jan 10, 2005, at 1:25 AM, Helmut (DF7ZS) wrote:
> 
>> Hi there.
>>
>> I had some problems with my Alpha 91b yesterday.
>> Maybe somone can have a good guess based on the symtoms I had:
>>
>> 10m band. Tuning with 10w resulted in about 800w out - as usual.
>>
>> 30-60w input resulted in solid 1k out - I remember it was more before
>> ???
> 
> Your 8874s may have gold contamination on the cathodes.  The gold comes 
> from the grid-plating and gold poisons emission, so P-out drops.  
> However, the problem can usually be corrected.  Do you have access to a 
> high-pot tester?
>>
>> I tried to make the fine tuning with 70w carrier - did that before - 
>> but
>> the amp imidiatly went on "FAULT" !
>>
>> The SWR was perfect on 10m - same results on 15m as well.
>>
>> On 20m it produced some more output, but also here I was not abel to 
>> get
>> the red 1.5k LED to lit - as it usually does on all bands. :-( Also 75w
>> carrier results imidiatly in "FAULT" ....
>>
>> I did not have a dummy load for high power available for any further
>> testing.
>>
>> The IP did not WENT over 1A before the fault came.
>>
>> Could it be that one tube is down ?
>>
>> 73sss
>>
>> Helmut
>>
>> www.df7zs.de
>> www.skydive-video.de
>>
>>
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>>
>>
> 
> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
> 
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