[Amps] Gettering 4CX800A GU74b

[Jason Buchanan]

Harold B. Mandel wrote:

>After trying out an EMTRON DX-3 and finding it
>prone to self-oscillation without any neutralization circuitry
>and susceptible to RF Feedback at 18MHz, (enought to illuminate
>all the LEDs on the bar graphs, all at once),
>
>And in addition to finding a tube socket that was ancient and
>a 12 year old tetrode in a supposedly "new" amplifier, I wonder
>what kind of surprises awaits owners of the DX-4?????
>
>  
>

Can't comment about the rf feedback setting up a carnival light show on 
18MHz but i've seen a few new amps shipped with pretty old tubes.  
Zillions of these tubes built in the early 90s.  Ray Cronin makes 
special mention of the warranty going bye-bye if you put another tube in 
your qrotec amp that you didn't buy from qrotec - they supposedly stoke 
up the getter and burn them in good and long. 

http://www.qrotec.com/tubewarn.html

IF YOU USE TUBES OTHER THAN THE ONES DELIVERED WITH YOUR AMPLIFIER, QRO 
TECHNOLOGIES IS NOT RESPONSIBLE FOR ANY DAMAGE CAUSED BY THOSE TUBES. 
YOUR WARRANTY WILL BE VOID AS IT RELATES TO ANY DAMAGE CAUSED BY THOSE 
TUBES. YOU WILL BE RESPONSIBLE FOR THE REPAIR COSTS AND RETURN SHIPPING.

THE 4CX800A (GU74b) TUBE MUST BE PROPERLY GETTERED AND TESTED BEFORE 
USE. THE TUBES SUPPLIED WITH OUR AMPLIFIER HAVE BEEN GETTERED AND 
TESTED. TUBES SUPPLIED BY OTHER VENDORS HAVE NOT BEEN PROPERLY GETTERED 
AND TESTED. THESE TUBES HAVE A STRONG TENDENCY TO ARC CAUSING DAMAGE TO 
THE AMPLIFIER. WE STRONGLY URGE YOU TO MAKE SURE ANOTHER TUBE SUPPLIER 
GETTERS AND TESTS THE TUBES HE SELLS AND GUARANTEES THOSE TUBES.

73s

Ray W. Connin, KB8VU
QRO Technologies, Inc.


This seems reasonable to me - and as long as they're not pushing up the 
price of hand-gettered replacement tubes so much the better.  ("Would 
you like to supersize that amplifier?")  


73 Jason N1SU