[Amps] 572b

[Roger (K8RI)]

On 5/2/2013 3:32 PM, MU 4CX250B wrote:
> I'm afraid I don't understand why the plate dissipation would affect
> longevity, provided the tubes have adequate cooling. Exceeding rated
> grid current or plate current, or using the wrong filament voltage
> could kill the tubes, as could  inadequate cooling, but I don't see
> why running the tubes at their rated dissipation with plenty of air
> would shorten tube life, if all other tube parameters were within
> specs,

That's because you are interested in the emission capabilities.  If it 
wont even make the plate dissipation rating, something is wrong.

Look up the tube data sheet and see what the max plate current should 
be.  The tube should be capable of this figure as a minimum.  You are 
really checking the emission.


73

Roger (K8RI)


> 73,
> Jim w8zr
> Sent from my iPhone
>
> On May 2, 2013, at 4:22 PM, Jeff Blaine <keepwalking188 at yahoo.com> wrote:
>
>> I have used about 8 of the Chinese 572 specifically for torture testing in RTTY service and I can say without qualification that the plate dissipation limit (IIRC 160w) is not something which will keep the tube in long service. But whipping the hell out of these tubes in AM/FM/RTTY service with all the guns blazing is not the common application.
>>
>> I would expect the current breed to give long SSB service as long as tuning is done properly and kept to a minimum.  For CW, almost as well.  From there, it goes down hill fast.
>>
>> Comparing them with prior generations makes no sense because there are virtually zero NOS old tubes remaining.  You either buy the Chinese (through some direct or distribution method) - and that is the only source available and take what service life you can get.  Or you can flip to another tube type at some considerable amount of work and expense.
>>