[AMPS] YC156 whats the point

[Richard W. Ehrhorn]

Hi Andy...

TheYC-156 (as I think has been mentioned numerous times in the past here) 
is actually a 3CX15000B7 outfitted with a 5kW cooler specifically for 
highly linear MRI rf pulse use. (High field MRI typically may use up to 
25kW peak rf pulse, but only a few hundred watts average, output - hence 
does not need a huge cooler. The 3CX15,000B7 data is 100% applicable to the 
3CPX5000A7/ YC-156, within its dissipation rating of course.

MRI guys typically specify linearity as a transfer function (+/- dB 
variation in Po/Pi) rather than in terms of IM. If I remember the spec 
correctly, our 25 kW amps had to test out better than +/- 0.5 dB linearity 
from 25 kW down to 2.5 W output (40 dB). IM numbers would depend somewhat 
on actual shape of that small nonlinearity, but I'd bet it's better than 
-40 dB ref peak output.

73,     Dick    W0ID    ex-W4ETO

-----Original Message-----
From:	john merryman [SMTP:andy_m_99@yahoo.com]
Sent:	Wednesday, February 24, 1999 2:01 AM
To:	amps@contesting.com
Subject:	[AMPS] YC156 whats the point




Am i missing something about the YC156. It has 5k plate dissipation,
its rated for pulse use. What would be the realistic operating
parameters in SSB,  to stay within the plate dissipation of 5K. You
end up with a tube that is similar to a 3cx3000 output wise, with a
very poor 3rd order imd figure. The data sheet does not mention any
high linearity figures, is this urban myth?

I think the 8171 in class A would be more linear and have a better IMD
figure. The 8171 would also have more grunt. But i might be missing
the point of this tube. Please explain why this tube would be favoured?

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