Alpha 8410 Linear Amplifier User Manual
RKR Designs LLC
Preparing Your Station
DOCNUMBER 8410
Document Issue 1.1
Page 3–4
August 2015
33
3
3.2 Limitations of Operation at Nonstandard Voltage
Electrical-power equipment draws twice as much primary current from
120-V mains as from 240-V mains. Therefore, if you operate the Alpha
8410 on typical 120-V/20-A household circuit without exceeding the 20-
A circuit rating, you limit maximum peak power output to ~600–1000 W.
For expected behaviors at nonstandard line voltages, see
Table 3-1
.
Table 3-1
Amplifier behavior with nonstandard line voltages
Line voltage
Expected behavior
Low: 90–130 V
For a line voltage of <120 V, do not expect to be
able to get 1500 W output. For maximum
efficiency, tune the amplifier for no more than
1000-W output.
For a line voltage of 110–130 V, 1500 W PEP
operation (CW or SSB) may be possible if your
AC line service has sufficient current capacity (30-
A circuit recommended). However, 1500 W
continuous should not be expected.
High: >250 V
Tube lifetimes may be reduced. Ask your utility
company if they can reduce your line voltage. If
this is not possible, consider placing your own
step-down transformer in line between the AC
outlet and the amplifier. A transformer with at
least 4-kVA rating is required, due to the nature of
the current waveform in the primary. Another
choice for voltage control, a ferroresonant voltage
regulator, is an expensive solution, but is a good
way to stabilize primary voltage.
NOTE
If you intend to operate the amplifier at ~120 V or if other equipment
draws current from the same circuit as the amplifier, the following
apply:
1. Ensure that the AC cord is not coiled too tightly or placed where
normal air flow is restricted, causing it to overheat.
2. Change the lower 2-A fuse on the rear panel to a 5-A fuse to allow
for the increased in-rush current.
