[Amps] Chinese Tubes VTU 4CX1000

[hp]

Anecdotal - Bought 8410 -mid 2014 -came with 2 VTU-4CX1000s Chinese variety - in 2 weeks one filament opened - ALPHA sent me another - about a year later one started popping over just sitting there idling which blew cathode resistors - I put new resistors in -same deal every few weeks -(of course after warranty was over) -- 

ALPHA could not get more 4CX1000s and I did not see any source I particularly wanted to risk. So we worked out a deal to get two 4CX1500s and ALPHA would burn them in for me before shipping. Those 4CX1500s have been trouble free- for about 6 years or so - fingers crossed. 

I had no way to see which of the VTU-4CX1000s was bad -could not find anyone locally with a hipot at a sane price. 

ALPHA suggested I try the tubes one at a time - I could not see waiting whatever time it took to have the bad one identified and replace the cathode resistors again. About a year ago I gave them to a guy in Tuscon -he sent them to a rebuild facility company in Florida who reported that yes one was fine still met specs but the other one was marginal breakdown -still usable if you wanted to suffer the consequences or run at lower plate voltage. 

So guess thats 2 out of 3 4CX1000s were bad in first 2 years. 
Now you must factor in my "Lucky Pierre"factor - 


FWIW - 

Hank K7HP 



>Message: 1 
>Date: Sat, 22 Jan 2022 17:57:41 -0600 
>From: Rob Atkinson < ranchorobbo at gmail.com > 
>To: MU 4CX250B < 4cx250b at miamioh.edu > 
>Cc: BILL KENNAMER < k5fuv at prodigy.net >, Louis Parascondola 
> < gudguyham at aol.com >, " amps at contesting.com " < amps at contesting.com > 
>Subject: Re: [Amps] new Alpha 
>Message-ID: 
> < CALWD7Z4jUQDY4KL9pMCayJD-7Zk-9WzE=e8sHivaAWgzHvk=8w at mail.gmail.com > 
>Content-Type: text/plain; charset="UTF-8" 
> 
>On Sat, Jan 22 , 2022 at 8:31 AM MU 4CX250B < 4cx250b at miamioh.edu > wrote: 
>> Is there hard evidence that Chinese tubes are inferior? 
> 
>If you mean statistical data, I don't know of any. RF Parts may keep 
>track of this.