[Amps] 4CX250 MSDS SHEET

[Ian White GM3SEK]

Karl-Arne Markström wrote:
>Years ago, I contacted CPI/Eimac about the possible use of BeO in
>ordinary power tubes, and got the answer that the external anode/air
>cooled types did not use BeO in their construction. The only current
>production tubes using BeO were the conduction cooled types.
>
>My specific request was about the P290A 5 kW pentode, but the answer
>from CPI covered all their small and medium size transmitting tubes.
>
>The amplifier group described here fits in to the Marconi H1000
>distributed amplifier, that could be found in some early frequency-
>hoppers and countermeasures systems. Also, British coastal radio used
>such amplifiers in some MF telephony and radio-telex installations.
>

Yes, that all fits together - the 4CX250B"M-for-Marconi".

Mike, you probably have all the evidence you need to tear up the 
beryllium emergency procedure. If the Navy wants more, then call Eimac.


73 from Ian GM3SEK




>----Ursprungligt meddelande----
>Från: ke6cvh at yahoo.com
>Datum: 12-12-2007 13:15
>Till: <amps at contesting.com>
>Ärende: Re: [Amps] 4CX250 MSDS SHEET
>
>Ian,
>  They are not coaxial based and have pins, I was typing from memory
>and they are 4CX250BM.  They go to an HF amplifier group made by
>Marconi (7amp groups mean 280 of the tubes or 40 per amp group for a
>total of 7KW combined).  I am not the tech. on this system and the
>young guy who works on them who is pretty much on par with an apliance
>operator practically works for me.  They use tubes for each band is the
>reason for so many.  They also use the same tubes to drive pairs of the
>finals.  Thanks for the clarification.
>  I have often wondered why they use such a tiny tubes and have
>thought possibly the 1200VDC plate potential allows them to work over a
>broader range of frequencies without being tuned but that is a SWAG.
>73,
>Mike
>
>
>
>----- Original Message ----
>From: Ian White GM3SEK <gm3sek at ifwtech.co.uk>
>To: amps at contesting.com
>Sent: Wednesday, December 12, 2007 7:51:29 PM
>Subject: Re: [Amps] 4CX250 MSDS SHEET
>
>mike kendall wrote:
>>Pete,
>>  The only tubes I have seen with pink ceramic is the russian ones
>that
>>I've bought off of Ebay and from friends.  I have to wonder if the
>>russian ones have BeO?
>>73,
>>Mike
>>
>>
>>
>>----- Original Message ----
>>From: Pete Smith <n4zr at contesting.com>
>>To: mike kendall <ke6cvh at yahoo.com>
>>Sent: Tuesday, December 11, 2007 10:04:21 PM
>>Subject: Re: [Amps] 4CX250 MSDS SHEET
>>
>>Isn't BeO ceramic pink?
>>
>>73, Pete N4ZR
>>
>>At 05:26 AM 12/11/2007, you wrote:
>>>Hello,
>>>  We have a piece of equipment at work with quite a few 4CX250M
>(Mobile
>>> version that is more rugged than the 4CX250R) tubes in the
>equipment.  I
>>> was asked if the ceramic portion of the tube is berrylium oxide or
>if
>>> there is any berrylium oxide in the tubes.  I am fairly certain
>that is
>>> the case but could not find any hard data on the internet to
>confirm so
>>> am asking the group if that is the case.
>>>73,
>>>Mike
>
>
>
>"Pink BeO ceramic" is an urban legend.
>
>Right here in 1999, "John T. M. Lyles" wrote:
>>
>> Thanks for the statement below, to help clarify this topic on BeO.
>> The pinkish ceramic on old RCA tubes was made by a company in
>> Frenchtown (NJ, NY, PA?), so was called Frenchtown ceramic.
>> Sometimes there is a purplish hue to it. Svetlana has some sort of
>> similar material, from another source. Manganese is in it. And yes,
>> it is not  BeO. BeO is present in some conduction cooled connector
>> blocks on power tubes, and on the undersides of many RF power
>> transistors,  between the device and the bottom flange. The white
>> top cap is usually alumina ceramic.
>>
>> Eimac stayed away from using the pink ceramic for marketing reasons.
>> Technically, Frenchtown ceramic made very good tubes, and many
>> of our > 3MW triodes, Burle/RCA 7835, had pink. Nowadays they are
>> all white.
>
>>From http://www.svetlana.com/docs/tubeFAQ.html [CAPITALS added for
>emphasis]:
>
>"Q. Why is your ceramic pink?
>A. Svetlana ceramic power tubes are manufactured with high-purity,
>high-alumina ceramic with CHROMIUM and MANGANESE additives. The
>combination of chromium and manganese with high alumina ceramic
>results
>in a true chemical bond in the metal-to-ceramic brazing process.
>These
>additives also give Svetlana ceramic tubes their distinctive
>appearance.
>The stronger bond allows a higher processing temperature than
>typically
>used by manufacturers in the West. A high-temperature bake-out
>process
>drives gasses from the internal electrodes during vacuum processing.
>Clean high-temperature processing means long operating life..."
>
>Unfortunately the svetlana.com website is long gone, but I seem to
>remember that the complete FAQ also mentioned beryllium more
>specifically. There may be someone here who still has that complete
>document.
>
>
>Mike, your other post about shipboard amplifiers using very large
>numbers of tubes raises doubts: did you really mean "4CX250M"? The
>250M
>is a coaxial-based tube, but there is also a 4CX250BM which has the
>regular pin base.
>
>The BM fits your description much better, because it was specifically
>supplied for distributed amplifiers which use large numbers of tubes.
>I
>just confirmed that my two Eimac BMs have white ceramic. Somewhere I
>also have a pair of Svetlana BMs which are pink - but that's due to
>chromium and manganese.
>
>You don't say who made the tubes that you have, but if it's Eimac,
>you
>should be able to get a definitive statement from their product
>support
>team:
>Tel: +1 (800) 414-8823
>Email: powergrid at cpii.com
>
>
>

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