On Oct 21, 2004, at 3:14 AM, Jason Buchanan wrote:
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.
Ray -- How does one getter a 4cx800A?
73s
Ray W. Connin, KB8VU
QRO Technologies, Inc.
...
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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