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Re: [Amps] [??????????????]Re: 3-500Z convertion

Subject: Re: [Amps] [??????????????]Re: 3-500Z convertion
From: Jan Erik Holm <sm2ekm@telia.com>
Date: Sun, 23 Jul 2006 18:47:29 +0200
List-post: <mailto:amps@contesting.com>
Oh it was a TL922, my misstake.
In any case it should be very similar with a TL922.
Just check so you get correct operating point (ZSAC) for
zero bias, however I more or less "know" that the 4X500
doesn´t work in GG.

73 Jim SM2EKM
--------------

Hsu wrote:

> Jim,
>   My TL922 was still on its way.if I get it I'll test the 4X500.
>        The FU-500F (4X150) was very easy to get and very very cheap.
>              73! Hsu
> 
> 
> As far as I remember you can not run 4X500´s in zero bias GG,
> you will not be able to get correct ZSAC for linera operation.
> 4X500´s need screen and grid voltages to get correct operating
> point.
> 
> 4-250A or 4-400A or C is OK in SB-220. Just tie all grid pins together
> and ground them directly, also you must short out the "bias"
> zener diode to get correct ZSAC, maybe adjust with a string of
> diodes to get correct ZSAC.
> 
> 73 Jim SM2EKM
> 
> PS: Think I remember that some 4-400´s was a bit too tall for
> the PA compartment lid to fit, 4-250A is never a problem.
> ---------------
> 
> Hsu wrote:
> 
> 
>>Thanks Peter!
>>    I have got a a died  TL922  as a junk,I only pay $100 for it.so I don't 
>> want pay for it too much.Althought the 3-500Z are made in China, but I call 
>> the factory, They ask me pay $500 for a matched pair!Mr.Richard L. Measures 
>> have mentioned in the list that  3-500Z can replace by 4-400(need some 
>> work),I have a pair  4-400C, but I just test them, they all died!in this 
>> weekend, I check my junk box, and find out some NOS Chinese FU-500Fs(same as 
>> 4X500A) and its socket, I just read its datasheets , I found the screen and 
>> grid  dissipation power not too small, so,I think maybe it can work in GG 
>> and cathode drive.It have same  volt and cureent of   filament as 3-500Z.  
>>  73! Hsu 
>>
>>  
>>----- Original Message ----- 
>>From: "Peter Chadwick" <g3rzp@g3rzp.wanadoo.co.uk>
>>To: "Hsu" <Jbenson@sohu.co>; <amps@contesting.com>
>>Sent: Sunday, July 23, 2006 7:14 PM
>>Subject: Re: [Amps] 3-500Z convertion
>>
>>
>>
>>
>>>Hsu said:
>>>
>>>
>>>>My TL922's 3-500Zs died,I have some 4X500As,it seems the 3-500Z can 
>>>>convertion by 4X500A, <
>>>
>>>The 4X500A is an external anode tube, so the cooling won't be right, it 
>>>needs a different socket, and it's a tetrode. You'd need to do soem careful 
>>>calculation to determine if the grid and screen dissipations would be 
>>>exceeded. All in all, i'd say buyin a pair of new 3-500Z is a better way to 
>>>o.
>>>73
>>>Peter G3RZP
>>>
>>>
>>>
>>>
>>>
>>>========================================
>>>Message Received: Jul 23 2006, 11:54 AM
>>>From: "Hsu" 
>>>To: amps@contesting.com
>>>Cc: 
>>>Subject: [Amps] 3-500Z convertion
>>>
>>>Hi, I'm a new member.My TL922's 3-500Zs died,I have some 4X500As,it seems 
>>>the 3-500Z can convertion by 4X500A, Does anyone have this experience?Thanks 
>>>in advance!
>>>73! Hsu
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>>
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> 
> 
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