[Collins] 30S-1 final 4CX1000 and 4CX1500 poor terminology

[Dr. Gerald N. Johnson]

On Tue, 2007-09-11 at 14:46 -0500, Phil M. wrote:
> While I understand and have enjoyed the discussion, I believe the
> tube designation terminology has been very careless.  First of all,
> people have been talking about the 4CX1500 which is not very
> accurate.  The tube suitable for use in the 30S-1 is the 4CX1500B...
> please note the B.  According to the 1975 Eimac catalog, there is
> a 4CX1500A which has a filament requirement of 5 volts at 38 amps
> versus the 45CX1500B which needs 6 volts at 10 amps....a minor
> difference :-)  And, as someone pointed out earlier, the 4CX1500B is
> listed as designed for SSB with lower IMD.
> 
> BTW, the same 1975 catalog lists a 4CX1000K with virtually the
> same characteristics as the 4CX1000A but with a solid screen ring....
> I've never come across one of these.
> 
> 73, Phil
> W5BVB
> 
The solid screen ring is supposed to make the tube more stable at VHF,
e.g. easier to be bypassed well. The 30S-1 and all larger Collins
linears have no screen bypasses. Bolting the screen ring to the deck
solves all kinds of fragility in screen bypass capacitors though it
complicates the power supply and metering.

Good point on the total tube nomenclature. There have been some drastic
differences between Eimac tubes with similar numbers (almost always
based on plate dissipation) and envelopes and capabilities. Look a the
X600s for extreme examples.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer