changes to the open circuit condition) may be performed
in the presence of a signal, provided the user limits the current to within 1.5A peak.
Specifications
Open Circuit Voltage
2000Vpk max.
Tube Load Current
Values < 256ohm : <500mArms (continuous)
Values 256-510ohm : <360mArms (continuous)
Values 512-1022ohm : <300mArms (continuous)
Values 1022-2046ohm : <220mArms (continuous)
Values 2048-3968ohm : <90mArms (continuous)
Values 4096-8064ohms : <45mArms (continuous)
Values 8192-16256ohms : <25mArms (continuous)
Values 16384-32256ohms : <12mArms (continuous)
Values >32256ohms : <8mArms (continuous)
All Values : <1.5A peak instantaneous
Tube Load Tolerance 1% + 0.3ohm
Filament Load Tolerance
5% + 0.1ohm
Filament Load Current
<1Arms (continuous), <2A peak instantaneous
Filament Load Power
<4.5W total per filament (average)
Load Capacitance
Values < 128ohm : <30pF
3

Values 128-2046ohm : <40pF
1 3

Values 2048-20352ohm : < 40pF
2

Values >20352ohm : < 27pF
Open Circuit : < 10pF
1
Integer increments of 128ohms < 27pF
3

2
Integer increments of 2048ohms < 27pF
3
As shown for 1561, 4pF lower for 1560 Filament Load Values
The user may select any three values for filament loads. Since the re is no allowance for
determining the actual filament load value fitted, the user should not mix filament load
selections within a facility.
Programming with the 2574R
The load for each tube is selected using codes 7000 through 9999. The first digit selects
one of the three filament load values, the last three digits represent the tube load
resistance. The values represented by the last three digits are encoded as follows :-
Codes 000 511 : Value = Code x 2
Codes 512 767 : Value = ((Code-512) x 4) + 1024
Codes 768 911 : Value = ((Code-768) x 128) + 2048
Codes 912 999 : Value = ((Code-912) x 512) + 20480

E.G.
1. to select the first filament load value, and a tube load of 100 ohms, the user selects
code 7050.
2. to select the first filament load value, and a tube load of 2000 ohms, the user
selects code 7756.
3. to select the second filament load value, and a tube load of 20000 ohms, the user
selects code 8908. The actual value will be nominally 19968 ohms.

Firmware Support in the 2574R and 1500 Chassis
This module is only supported by 2574R firmware revision 5.0 onwards, and 1500
chassis revision 3.0 onwards.