Hum RCA 4QR64X

4/23/2004 7:30:42 PMRobert Hott

I have an RCA model 4QR64X radio made in west Germany.So far have not been able to find schematic.
Plays great and I love the eye tube. The three sw bands
seem to be very sens.Problem is hum (120) cycle I think.Has variable trans for diff voltages.Tubes are
6X4,6BE6,6BA6,6AU6,6AQ5 and EM34.New tubes and 47 Mf
cap has been replaced (added?)Hum just a little to loud for comfort.Not affected by volume or tuning
control.Ant is long wire. Help.

4/23/2004 7:43:13 PMNorm Leal

Hi Robert

A radio has at least 2 electrolytic filter caps. You mentioned a 47 mfd. There should be another one. When they are replaced at least one lead of the old one should be removed.

Electrolytic filter caps dry out over time and allow hum. They can also short and damage other components in a radio.

Norm

:I have an RCA model 4QR64X radio made in west Germany.So far have not been able to find schematic.
:Plays great and I love the eye tube. The three sw bands
:seem to be very sens.Problem is hum (120) cycle I think.Has variable trans for diff voltages.Tubes are
:6X4,6BE6,6BA6,6AU6,6AQ5 and EM34.New tubes and 47 Mf
:cap has been replaced (added?)Hum just a little to loud for comfort.Not affected by volume or tuning
:control.Ant is long wire. Help.
:
:

4/24/2004 9:17:57 PMRobert Hott

:Hi Robert
:
: A radio has at least 2 electrolytic filter caps. You mentioned a 47 mfd. There should be another one. When they are replaced at least one lead of the old one should be removed.
:
: Electrolytic filter caps dry out over time and allow hum. They can also short and damage other components in a radio.
:
:Norm
:
::I have an RCA model 4QR64X radio made in west Germany.So far have not been able to find schematic.
::Plays great and I love the eye tube. The three sw bands
::seem to be very sens.Problem is hum (120) cycle I think.Has variable trans for diff voltages.Tubes are
::6X4,6BE6,6BA6,6AU6,6AQ5 and EM34.New tubes and 47 Mf
::cap has been replaced (added?)Hum just a little to loud for comfort.Not affected by volume or tuning
::control.Ant is long wire. Help.
::
::

4/24/2004 9:26:43 PMRobert Hott

:Hi Robert
:
: A radio has at least 2 electrolytic filter caps. You mentioned a 47 mfd. There should be another one. When they are replaced at least one lead of the old one should be removed.
:
: Electrolytic filter caps dry out over time and allow hum. They can also short and damage other components in a radio.
:
:Norm
:
::I have an RCA model 4QR64X radio made in west Germany.So far have not been able to find schematic.
::Plays great and I love the eye tube. The three sw bands
::seem to be very sens.Problem is hum (120) cycle I think.Has variable trans for diff voltages.Tubes are
::6X4,6BE6,6BA6,6AU6,6AQ5 and EM34.New tubes and 47 Mf
::cap has been replaced (added?)Hum just a little to loud for comfort.Not affected by volume or tuning
::control.Ant is long wire. Help.
::
::Found another small metal electrolytic marked
25uF but I don't understand voltage seems to be
12/15V- Found similar one marked west Germany
32uF/150v- is this an ok replacement?

4/24/2004 10:38:43 PMNorm Leal

Hi Robert

You can always use a cap with higher voltage rating. Using a slightly higher capacity is also ok.

A cap with low voltage rating wouldn't be a power supply filter. I would expect a voltage rating of several hundred volts?

Norm

::Hi Robert
::
:: A radio has at least 2 electrolytic filter caps. You mentioned a 47 mfd. There should be another one. When they are replaced at least one lead of the old one should be removed.
::
:: Electrolytic filter caps dry out over time and allow hum. They can also short and damage other components in a radio.
::
::Norm
::
:::I have an RCA model 4QR64X radio made in west Germany.So far have not been able to find schematic.
:::Plays great and I love the eye tube. The three sw bands
:::seem to be very sens.Problem is hum (120) cycle I think.Has variable trans for diff voltages.Tubes are
:::6X4,6BE6,6BA6,6AU6,6AQ5 and EM34.New tubes and 47 Mf
:::cap has been replaced (added?)Hum just a little to loud for comfort.Not affected by volume or tuning
:::control.Ant is long wire. Help.
:::
:::Found another small metal electrolytic marked
:25uF but I don't understand voltage seems to be
:12/15V- Found similar one marked west Germany
:32uF/150v- is this an ok replacement?
:

2/23/2005 8:34:42 PMjames dean

:I have an RCA model 4QR64X radio made in west Germany.So far have not been able to find schematic.
:Plays great and I love the eye tube. The three sw bands
:seem to be very sens.Problem is hum (120) cycle I think.Has variable trans for diff voltages.Tubes are
:6X4,6BE6,6BA6,6AU6,6AQ5 and EM34.New tubes and 47 Mf
:cap has been replaced (added?)Hum just a little to loud for comfort.Not affected by volume or tuning
:control.Ant is long wire. Help.

I found this same radio in my dad's attic. Can you tell me how old it is. Mine works fine but was wondering any information you could give me about it. I like the tuning eye too!!!!
:
:

2/27/2005 9:37:54 PMRobert Hott

::I have an RCA model 4QR64X radio made in west Germany.So far have not been able to find schematic.
::Plays great and I love the eye tube. The three sw bands
::seem to be very sens.Problem is hum (120) cycle I think.Has variable trans for diff voltages.Tubes are
::6X4,6BE6,6BA6,6AU6,6AQ5 and EM34.New tubes and 47 Mf
::cap has been replaced (added?)Hum just a little to loud for comfort.Not affected by volume or tuning
::control.Ant is long wire. Help.
:
:I found this same radio in my dad's attic. Can you tell me how old it is. Mine works fine but was wondering any information you could give me about it. I like the tuning eye too!!!!
::
So far I have no info-but I have add in Mar ARC and will post if we get any feedback.
Bob
::