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Re: [Amps] QEX Innovative Tube Linear?

Subject: Re: [Amps] QEX Innovative Tube Linear?
From: "Will Matney" <>
Date: Fri, 07 Jul 2006 22:35:11 -0400
List-post: <>
See below;

*********** REPLY SEPARATOR  ***********

On 7/7/06 at 8:39 PM Tom W8JI wrote:

>> Only for the 8950 and M-2057 (or Y-2057) as they were the 
>> only ones that GE said were for RF amplifier service. The 
>> M-2057 was a custom tube that was manufactured by GE. They 
>> took an 8908's guts and placed them in a 12 pin compactron 
>> base which was what a GE engineer told me. The only specs 
>> I have on the 8908 is in a GE tube applications book. I 
>> have the GE application sheets on the 8950 and M-2057. All 
>> the other sweep tubes were based around TV horizontal 
>> output service, however the maximum DC anode voltages 
>> still apply.
>I'm a little puzzled, and this may be confusing other people 
>As I recall you stated quite emphatically everyone should 
>follow the letter of a spec sheet regardless of what factory 
>engineers might OK and even if actual operation proved the 
>change perfectly acceptable. That was for a momentary tuning 

Where's this so-called approval from the factory engineers? What factory 
engineers? Is this in writing? I'd like to see it myself. Try getting a 
warranty on a sweep tube after telling the seller or manufacturer it's been 
used in a RF amplifier. I'll bet several on here that's had any experience with 
them knows what Radio Shack did on it's lifetime tube warranty about them. Ask 
Merit at RF Parts if he'll give a warranty on a sweep tube used in a RF 
amplifier. ask Richardson the same.

>If I think along the very same lines, it also seems totally 
>unacceptable to run a tube in linear service when linear 
>operation is NOT specified, and it also seems unacceptable 
>to use data sheets for pulsed horizontal sweep service in 
>linear service applications. Pulse and linear service are 
>worlds apart in every rating except filament voltage.

Again, no tube manufacturer ever gave warranties for sweep tubes in amplifiers 
(except GE). Every OEM bought from CECO or Richardson at one time, and the only 
warranties were given by the amplifier manufacturers themselves. At that, most 
amp manufacturers gave no warranties on sweep tubes. The M-2057, and 8950 are 
an exception as long as they were ran under the maximum design limits 
(design-maximum values). Those limits are what I posted earlier. These two 
sweep type tubes were the only two that GE specified as RF amplifier output 
tubes. Those are the only two I used besides experimenting with the Svetlana 

>We were all told that not following the exact letter of data 
>sheets would or could get engineering licenses revoked, it 
>could also run a business into bankruptcy from lawsuits. If 
>factory engineers aren't allowed to tell people it is OK to 
>operate tubes outside of the exact letter of data sheets for 
>few moments of tuning, and if tube engineers are not allowed 
>to make exceptions for a few moments of tuning, wouldn't 
>that apply even more here since this is continuous operation 
>outside of the data sheets?

Watch what is quoted as some here have saved the posts. I said "I would have 
been fired" for designing something outside the limits of a specification, not 
anyone else. I can tell you also that an inside engineer can tell you anything, 
and if you don't have it in writing, the manufacturer can surely back out on a 
warranty if they want to. The comparisons about someone losing a license 
concerned only myself (being fired) or an example about an engineer causing 
bodily harm or death of an end user because of faulty equipment. If a law suit 
begins, and something is designed past its stated maximums, the engineer can be 
held liable for it. Any engineer can tell you this. If they are the engineer in 
charge, they are responsible liability wise. The only out is to have a letter 
from the parts manufacturer giving a go-ahead for one particular use.

>For example, my RCA data sheets for the 6LQ6 only have 
>constant current charts that go to 450 volts dc. Why is it 
>now OK to specify 900 volts when it is off the charts, when 
>other people (even with manufacturer's permission) aren't 
>allowed to do that? Since the tubes isn't spec'ed for linear 
>service, doesn't that violate good engineering practices?

900 Vdc is the design-maximum by GE, I'm not quoting RCA. Read the GE sheets 
and you'll see the difference. Most sweep tube curves don't show the 
design-maximum anode voltage. They stop about 1/2 way or a little below.

Quote from all GE application sheets including the M-2057 and 8950;

"Design-maximum ratings are limiting values of operating and environmental 
conditions applicable to a bogey electron tube of a specified type as defined 
by its published data, and should not be exceeded under the worst probable 

"The tube manufacturer chooses these values to provide acceptable 
serviceability of the tube, making allowance for the effects of changes in 
operating conditions due to variations in the characteristics of the tube under 

"The equipment manufacturer should design so that initially and throughout life 
no design-maximum value for the intended service is exceeded with a bogey tube 
under the worst probable operating conditions with respect to supply voltage 
variation, equipment component variation, equipment control adjustment, load 
variation, signal variation, environmental conditions, and variations in the 
characteristics of all other electron devices in the equipment".

End Quote.

Notice GE says "equipment control adjustment".......

>Perhaps I'm missing something?

Yes, a good bit.

>73 Tom



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