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@gmail.com >
>To: MU 4CX250B < 4cx250b@miamioh.edu >
>Cc: BILL KENNAMER < k5fuv@prodigy.net >, Louis Parascondola
> < gudguyham@aol.com >, " amps@contesting.com " < amps@contesting.com >
>Subject: Re: [Amps] new Alpha
>Message-ID:
> < CALWD7Z4jUQDY4KL9pMCayJD-7Zk-9WzE=e8sHivaAWgzHvk=8w@mail.gmail.com >
>Content-Type: text/plain; charset="UTF-8"
>
>On Sat, Jan 22 , 2022 at 8:31 AM MU 4CX250B < 4cx250b@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.
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