AL80A Problems
 

Folks,

I just buy a used AL-80A. It is set on 120 V and without connecting
any rig i did connec to gnd and 120. When I turned on I am seeing then
HV is 2400V. AL80A manual is saying that no load must show 3100V. Is
this mean that I need a new 3-500Z or can be something else.

Thanks for the help.
Levent WW2L

In article ,
(Levent) wrote:

Folks,

I just buy a used AL-80A. It is set on 120 V and without connecting
any rig i did connec to gnd and 120. When I turned on I am seeing then
HV is 2400V. AL80A manual is saying that no load must show 3100V. Is
this mean that I need a new 3-500Z or can be something else.

Thanks for the help.
Levent WW2L

Check the HV meter resistors. They've been known to change value.

73
Dale, K9VUJ
--

In article ,
(Levent) wrote:

Folks,

I just buy a used AL-80A. It is set on 120 V and without connecting
any rig i did connec to gnd and 120. When I turned on I am seeing then
HV is 2400V. AL80A manual is saying that no load must show 3100V. Is
this mean that I need a new 3-500Z or can be something else.

Thanks for the help.
Levent WW2L

Check the HV meter resistors. They've been known to change value.

73
Dale, K9VUJ
--

Make sure to measure the actual line voltage. While low line voltage would
not cause the HV to read that low, it's always a good idea to know what it
is so you can set the taps correctly.

K8AC

"Levent" wrote in message
om...
Folks,

I just buy a used AL-80A. It is set on 120 V and without connecting
any rig i did connec to gnd and 120. When I turned on I am seeing then
HV is 2400V. AL80A manual is saying that no load must show 3100V. Is
this mean that I need a new 3-500Z or can be something else.

Thanks for the help.
Levent WW2L

Make sure to measure the actual line voltage. While low line voltage would
not cause the HV to read that low, it's always a good idea to know what it
is so you can set the taps correctly.

K8AC

"Levent" wrote in message
om...
Folks,

I just buy a used AL-80A. It is set on 120 V and without connecting
any rig i did connec to gnd and 120. When I turned on I am seeing then
HV is 2400V. AL80A manual is saying that no load must show 3100V. Is
this mean that I need a new 3-500Z or can be something else.

Thanks for the help.
Levent WW2L

In article ,
wrote:

In article ,
(Levent) wrote:

Folks,

I just buy a used AL-80A. It is set on 120 V and without connecting
any rig i did connec to gnd and 120. When I turned on I am seeing then
HV is 2400V. AL80A manual is saying that no load must show 3100V. Is
this mean that I need a new 3-500Z or can be something else.

Thanks for the help.
Levent WW2L

Check the HV meter resistors. They've been known to change value.

73
Dale, K9VUJ

A you don't have to have the power on to check the meter resistors.
Find them on the wiring diagram and lift one lead from the board then
using an ohm meter check and compare values with the schematic. If
memory is right it is a one percent resistor and one megohm. Might be
two though. You should be seeing around 3100 --3200 volts no load on
the HV meter, it will drop to perhaps 2800--2700 under load.

Be sure you have the power plug unplugged from the mains and wait at
least 30 minutes for the caps to discharge (NEVER TRUST BLEEDER
RESISTORS!!) then using a chicken stick to ground touch the capacitors
positive terminal to be sure there is no HV floating.

You're a ham and familar with all this stuff right?

If you're not sure about it, don't.

No joking matter 3 Kv is a killer!!! So No power on while you work on
it, Ok?

Dale, K9VUJ
--

In article ,
wrote:

In article ,
(Levent) wrote:

Folks,

I just buy a used AL-80A. It is set on 120 V and without connecting
any rig i did connec to gnd and 120. When I turned on I am seeing then
HV is 2400V. AL80A manual is saying that no load must show 3100V. Is
this mean that I need a new 3-500Z or can be something else.

Thanks for the help.
Levent WW2L

Check the HV meter resistors. They've been known to change value.

73
Dale, K9VUJ

A you don't have to have the power on to check the meter resistors.
Find them on the wiring diagram and lift one lead from the board then
using an ohm meter check and compare values with the schematic. If
memory is right it is a one percent resistor and one megohm. Might be
two though. You should be seeing around 3100 --3200 volts no load on
the HV meter, it will drop to perhaps 2800--2700 under load.

Be sure you have the power plug unplugged from the mains and wait at
least 30 minutes for the caps to discharge (NEVER TRUST BLEEDER
RESISTORS!!) then using a chicken stick to ground touch the capacitors
positive terminal to be sure there is no HV floating.

You're a ham and familar with all this stuff right?

If you're not sure about it, don't.

No joking matter 3 Kv is a killer!!! So No power on while you work on
it, Ok?

Dale, K9VUJ
--

I'm not too familiar with that amp but... the specs on the Ameritron site
calls for 2700 volts with the AL80B under load and 3100 volts no load. 2400
is too low...... the HV shouldn't, I believe, change with a soft tube as
it's a measure of the transformer voltage. In my experience the main cause
of low plate voltage is low line voltage at the outlet.

The meter may be off some .... and 120 volts isn't exactly well regulated
voltage. Double check the tap set-up on the power transformer.... make sure
that is set for your line voltage. Measure your line voltage and set the
taps to the closest voltage...The info on the AL80B indicates it's a multi
voltage type transformer with 14 taps from 90 to 230 volts...but I'm not
sure about the AL80A.

DO NOT fool around inside an amplifier if you are not knowledgable about
working around high voltage and discharging capacitors. The HV in an
amplifier is LETHAL. (usual disclaimer grin)

Mike, W9WIS

I'm not too familiar with that amp but... the specs on the Ameritron site
calls for 2700 volts with the AL80B under load and 3100 volts no load. 2400
is too low...... the HV shouldn't, I believe, change with a soft tube as
it's a measure of the transformer voltage. In my experience the main cause
of low plate voltage is low line voltage at the outlet.

The meter may be off some .... and 120 volts isn't exactly well regulated
voltage. Double check the tap set-up on the power transformer.... make sure
that is set for your line voltage. Measure your line voltage and set the
taps to the closest voltage...The info on the AL80B indicates it's a multi
voltage type transformer with 14 taps from 90 to 230 volts...but I'm not
sure about the AL80A.

DO NOT fool around inside an amplifier if you are not knowledgable about
working around high voltage and discharging capacitors. The HV in an
amplifier is LETHAL. (usual disclaimer grin)

Mike, W9WIS

Folks,

Thanks for all this valuable info. I did check a few things more. Power
outlet is showing 124 Volts on my Fluke. When I turned the amplifier I
am not seeing any voltage changes on my outlet. I did take a visual look
to the 3-500Z. I am not familiar about this tube but when I do up side
down very gently I do hear a metallic click noise. It looks like some
thing inside the tube is loose. I did not load any RF to the amp yet. I
don't want to guesswork anything Ameritron manual says 3100V I have to
see it at least 3000V. 600V difference is big. Is any one see low
voltage on the soft or bad 3-500Z ???

Thanks to all for the help and 73s
Levent


Michael Melland wrote:
I'm not too familiar with that amp but... the specs on the Ameritron site
calls for 2700 volts with the AL80B under load and 3100 volts no load. 2400
is too low...... the HV shouldn't, I believe, change with a soft tube as
it's a measure of the transformer voltage. In my experience the main cause
of low plate voltage is low line voltage at the outlet.

The meter may be off some .... and 120 volts isn't exactly well regulated
voltage. Double check the tap set-up on the power transformer.... make sure
that is set for your line voltage. Measure your line voltage and set the
taps to the closest voltage...The info on the AL80B indicates it's a multi
voltage type transformer with 14 taps from 90 to 230 volts...but I'm not
sure about the AL80A.

DO NOT fool around inside an amplifier if you are not knowledgable about
working around high voltage and discharging capacitors. The HV in an
amplifier is LETHAL. (usual disclaimer grin)

Mike, W9WIS