On 07/13/11 10:21 PM, Roger (sub1) wrote:
> On 7/13/2011 4:03 PM, Dr. David Kirkby wrote:
>> On 07/13/11 07:39 PM, ED MCKIE wrote:
>>> I read something a few days ago about people putting CPI / Eimac
>>> silkscreen
>>> on import tubes.
>>> TNX, Ed
>> Assuming you are talking about this auction
>>
>> http://cgi.ebay.com/Eimac-YU-158-8877-3CX1500A7-Power-Triode-/350477144083?pt=LH_DefaultDomain_0&hash=item519a10d013
>>
>> it's possible the "1" looks bigger due distortion caused by the perspective
>> and/or the use of a lens not suited to close up work. The anode appears to be
>> much deeper at the front than at the back.
>
> There is definately distortion due to lens focal length and distance to
> the subject, *but* if you look at the large "1" look at the sting of
> characters starting above it. The H in Hazardous is directly above the
> "1" and it is not distorted. Also if the "1" were distorted due to the
> focal lenght/distance the string of numbers should get larger as a
> function of distance. IOW the 0 would only be slightly smaller and the 3
> would be slightly smaller than the 0 with the difference rapidly
> diminishing with distance. Also you do not see the same distortion with
> the numbers under the Eimac Logo to the left. If you look at the anode
> size Vs distance that same change should apply to the lettering and
> numbers. The "1" is the only thing out of character for size.
>
> Would this indicate some one had made a change? I don't know, but I've
> seen date codes with the first digit larger before.
>
> 73
>
> Roger (K8RI)
To be honest if a company is capable of making an electron tube, with all
engineering that needs, then creating an Eimac silk screen, I'm sure they would
be capable of getting all the letters the same size!
In order of complexity.
1) Printing a string of numbers the same size - I can do that on my laser
printer or my inkjet.
2) Printing those numbers in a color and style very similar to Eimacs on a
piece
of metal that looks silver plated.
3) Making a collection of bits of metal look like an Eimac tube.
If the information about ETO is correct, then this does look suspicious, but
I'd
not worry about the date code.
eBay is full of scams. You just have to accept that. There are some bargains
and
some scams.
Even if the tube is not a fake, there's a good chance it is stolen.
Dave
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