I have a SB-200 that has very low idling current, normal idling current
should be 90ma, the low idling current is reading about 20-25 ma max...
Each tube draws only about 10 ma each.

Output is only about 250 watts maximum

Anyone familiar with the SB-200???

thanks

AB8RL Tom

Tom,
You did not give a lot of information but! assuming the high voltage to be OK
(aprox 2200 volts) and the tubes good. The operating bias on the grids is set
by the voltage droop across the relay coil in parallel with R18 a 2k resistor
and voltage divider resister R16 (33 ohm). this assumes that the bottom of R16
connected to the antenna relay jack is shorted to very near zero volts when you
key the rig. Bear in mind that the transmitt relay or transistor in your
xceiver must sink quite a lot of current. If the Relay or transistor in your
rig have resistance (pitted contacts ETC.) this resistance is in series with
R16 and could easily change the bias voltage to drop the idle current and also
the amount of drive required for the amp.

My guess is that if you relay jack to ground you will see the idle current jump
to the recommended 60 ma. Use caution as the jack has -160 volts DC on it and
enough current to really give the relay's in modern rigs a work out. You might
need to add an external keying relay.

good luck with the trouble shooting.
N0DG Don

Tom,
You did not give a lot of information but! assuming the high voltage to be OK
(aprox 2200 volts) and the tubes good. The operating bias on the grids is set
by the voltage droop across the relay coil in parallel with R18 a 2k resistor
and voltage divider resister R16 (33 ohm). this assumes that the bottom of R16
connected to the antenna relay jack is shorted to very near zero volts when you
key the rig. Bear in mind that the transmitt relay or transistor in your
xceiver must sink quite a lot of current. If the Relay or transistor in your
rig have resistance (pitted contacts ETC.) this resistance is in series with
R16 and could easily change the bias voltage to drop the idle current and also
the amount of drive required for the amp.

My guess is that if you relay jack to ground you will see the idle current jump
to the recommended 60 ma. Use caution as the jack has -160 volts DC on it and
enough current to really give the relay's in modern rigs a work out. You might
need to add an external keying relay.

good luck with the trouble shooting.
N0DG Don

Tom,
You did not give a lot of information but! assuming the high voltage to be OK
(aprox 2200 volts) and the tubes good. The operating bias on the grids is set
by the voltage droop across the relay coil in parallel with R18 a 2k resistor
and voltage divider resister R16 (33 ohm). this assumes that the bottom of R16
connected to the antenna relay jack is shorted to very near zero volts when you
key the rig. Bear in mind that the transmitt relay or transistor in your
xceiver must sink quite a lot of current. If the Relay or transistor in your
rig have resistance (pitted contacts ETC.) this resistance is in series with
R16 and could easily change the bias voltage to drop the idle current and also
the amount of drive required for the amp.

My guess is that if you relay jack to ground you will see the idle current jump
to the recommended 60 ma. Use caution as the jack has -160 volts DC on it and
enough current to really give the relay's in modern rigs a work out. You might
need to add an external keying relay.

good luck with the trouble shooting.
N0DG Don

Don...
Do you know if that keying requirement is the same for the SB220 and SB230?

.....Dave

"N0DG" wrote in message
...
Tom,
You did not give a lot of information but! assuming the high voltage to be
OK
(aprox 2200 volts) and the tubes good. The operating bias on the grids is
set
by the voltage droop across the relay coil in parallel with R18 a 2k
resistor
and voltage divider resister R16 (33 ohm). this assumes that the bottom of
R16
connected to the antenna relay jack is shorted to very near zero volts
when you
key the rig. Bear in mind that the transmitt relay or transistor in your
xceiver must sink quite a lot of current. If the Relay or transistor in
your
rig have resistance (pitted contacts ETC.) this resistance is in series
with
R16 and could easily change the bias voltage to drop the idle current and
also
the amount of drive required for the amp.

My guess is that if you relay jack to ground you will see the idle current
jump
to the recommended 60 ma. Use caution as the jack has -160 volts DC on it
and
enough current to really give the relay's in modern rigs a work out. You
might
need to add an external keying relay.

good luck with the trouble shooting.
N0DG Don

Don...
Do you know if that keying requirement is the same for the SB220 and SB230?

.....Dave

"N0DG" wrote in message
...
Tom,
You did not give a lot of information but! assuming the high voltage to be
OK
(aprox 2200 volts) and the tubes good. The operating bias on the grids is
set
by the voltage droop across the relay coil in parallel with R18 a 2k
resistor
and voltage divider resister R16 (33 ohm). this assumes that the bottom of
R16
connected to the antenna relay jack is shorted to very near zero volts
when you
key the rig. Bear in mind that the transmitt relay or transistor in your
xceiver must sink quite a lot of current. If the Relay or transistor in
your
rig have resistance (pitted contacts ETC.) this resistance is in series
with
R16 and could easily change the bias voltage to drop the idle current and
also
the amount of drive required for the amp.

My guess is that if you relay jack to ground you will see the idle current
jump
to the recommended 60 ma. Use caution as the jack has -160 volts DC on it
and
enough current to really give the relay's in modern rigs a work out. You
might
need to add an external keying relay.

good luck with the trouble shooting.
N0DG Don

Don...
Do you know if that keying requirement is the same for the SB220 and SB230?

.....Dave

"N0DG" wrote in message
...
Tom,
You did not give a lot of information but! assuming the high voltage to be
OK
(aprox 2200 volts) and the tubes good. The operating bias on the grids is
set
by the voltage droop across the relay coil in parallel with R18 a 2k
resistor
and voltage divider resister R16 (33 ohm). this assumes that the bottom of
R16
connected to the antenna relay jack is shorted to very near zero volts
when you
key the rig. Bear in mind that the transmitt relay or transistor in your
xceiver must sink quite a lot of current. If the Relay or transistor in
your
rig have resistance (pitted contacts ETC.) this resistance is in series
with
R16 and could easily change the bias voltage to drop the idle current and
also
the amount of drive required for the amp.

My guess is that if you relay jack to ground you will see the idle current
jump
to the recommended 60 ma. Use caution as the jack has -160 volts DC on it
and
enough current to really give the relay's in modern rigs a work out. You
might
need to add an external keying relay.

good luck with the trouble shooting.
N0DG Don