[Amps] brass or BNP hardware

DJ7WW dj7ww at t-online.de
Tue Nov 23 09:46:14 PST 2010


Yes, I know.
3 are sitting in my LK800-A with an external 3ph p/s.
Unfortunately my source for MRI tubes is using the 3CPX1500A7 but just the
standard 3CX800A7.

73
Peter

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Carl
Sent: Dienstag, 23. November 2010 18:37
To: DJ7WW; amps at contesting.com
Subject: Re: [Amps] brass or BNP hardware

No company uses the 3CX800A7 any longer. The 3CPX800A7 is cheaper and better

and rated at 3500V max in SSB service by Eimac.

Carl
KM1H


----- Original Message ----- 
From: "DJ7WW" <dj7ww at t-online.de>
To: <amps at contesting.com>
Sent: Tuesday, November 23, 2010 12:22 PM
Subject: Re: [Amps] brass or BNP hardware


>I got both data sheets.
> My saying is that specifications are far exceeded when 3x 3CX800A7 tubes 
> are
> run at 4KW out, not how far they can be pushed before the big bang 
> happens.
>
> The problem is the anode current and voltage limitation, not the 
> dissipation
> with 3CX800s and a large blower.
> Dissipation is smallest when anode current hits its maximum.
>
> The preliminary data sheet specs for absolutely maximum ratings in AB2 are
> 2500V 0.6A and the later specs are 2250V 0,6A.
>
> Running 6KW out with 3 of them exceeds all specs even more.
>
> And to repeat it, 4-400 specs can also be overrided easily with higher 
> anode
> voltages and more drive.
>
> I did 1200W out with a single 4-125 in the past when our regulations 
> limited
> us to 150W maximum dissipation for the tube(s) in the final according to 
> the
> data sheet.
> Eimac printed a special data sheet for their 3-150ZG showing 150W anode
> dissipation ;-)).
>
> 6KW out with 3x 4-400/QB4-1100 are easy and tubes are dirt cheap compared 
> to
> 3CX800A7.
> The pair of QB4/1100 in my L4B can be pushed to 4KW out at 4.5KV from my
> 3-ph power supply.
>
> 73
> Peter
>
>
>
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Shane Youhouse
> Sent: Dienstag, 23. November 2010 17:14
> To: amps at contesting.com; DJ7WW
> Subject: Re: [Amps] brass or BNP hardware
>
> 3 x 3cx800s will do a LOT of Pout.
>
> Command's does near 6 Kw.
>
>
> The 3CX800 has a pair of datasheets running around.  One shows Pout > 1200
> watts, another shows it at 750.
>
> 3 800s doing 4Kw is only 1300 watts a tube....  Easily accomplished, it's
> only 1.5 times Pdiss.
>
>
> 3 x 800s = 2400 watts of diss.  3 X 4-400s = 1200 watts of Pdiss.  I'm not
> a math major, but I fail to see how 1200 = 2400??????
>
>
> --Shane
> KD6VXI
>
>
>
>
> On Tue, 23 Nov 2010 07:58:41 -0800, DJ7WW <dj7ww at t-online.de> wrote:
>
>> Only if the tube specifications are far exceeded.
>> 3x 4-400 will do the same then.
>>
>> 73
>> Peter
>>
>> -----Original Message-----
>> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
>> Behalf Of Carl
>>
>> I just serviced a LK-800C and discovered 6-32 steel hardware in the RF
>> path
>> on both sides of the plate blocking cap. One side was darkened overall
>> and
>> the other was black where the threads entered the cap, it looked like
>> rust
>> under magnification. This amp will do an easy 3500-4000W + with
>> sufficient
>> drive.
>>
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>
>
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