Hello: i need information about this radio. It was made in Argentina in the 40'th.
It belongued to my grandfather but suddenly it stopped working.
Apparently someone try to repair it a long time ago, now I've decided to repair it by myself.
I need help because I believe that some valves are no in their right place.
The model is 875-MX

Thanx

I forgot to add extra information
The radio has 5 valves but I was able to identify 4
this are:
25Z6GT
6K8GT
6Q7-G
25L6GT

Hi Gaston

The missing tube would be 6K7. It might have had G or GT after the number. This determines the size and shape, electrically the same.

Since the radio wasn't made in the US Rider most likely doesn't have an exact schematic. Try 96X series. Where is says 6SQ7 you have 6Q7 and 6SK7 should be 6K7. These tubes serve the same purpose but do not have a top cap.

To change pages in Rider advance page number in the address.

http://www.nostalgiaair.org/Riders/RCA.htm

Norm

:I forgot to add extra information
:The radio has 5 valves but I was able to identify 4
:this are:
:25Z6GT
:6K8GT
:6Q7-G
:25L6GT

Norm: Thank you for the data. I have pictures of the Radio, tell me if you want me to send them.
I think that the tube 25Z6GT is bad, I see it trought the light and I see a conductor damaged. But I use the tester and apparently It's Ok, I think that it have a thin conductor in paralel.
Can you help me by sending me information on haw to test this tubes?
Thanx

:Hi Gaston
:
: The missing tube would be 6K7. It might have had G or GT after the number. This determines the size and shape, electrically the same.
:
: Since the radio wasn't made in the US Rider most likely doesn't have an exact schematic. Try 96X series. Where is says 6SQ7 you have 6Q7 and 6SK7 should be 6K7. These tubes serve the same purpose but do not have a top cap.
:
: To change pages in Rider advance page number in the address.
:
:http://www.nostalgiaair.org/Riders/RCA.htm
:
:Norm
:
::I forgot to add extra information
::The radio has 5 valves but I was able to identify 4
::this are:
::25Z6GT
::6K8GT
::6Q7-G
::25L6GT

Hi Gaston

25Z6GT is a dual diode rectifier. The tube has a 25 volt filament between pins 2 and 7. Plates, pins #3 and #5, usually tied to AC input. DC is on cathodes, pins 4 & 8. Be sure to check for shorts between elements.

Filter caps should be replaced if this tube is bad.

Norm

: Thank you for the data. I have pictures of the Radio, tell me if you want me to send them.
: I think that the tube 25Z6GT is bad, I see it trought the light and I see a conductor damaged. But I use the tester and apparently It's Ok, I think that it have a thin conductor in paralel.
: Can you help me by sending me information on haw to test this tubes?
: Thanx
:
::Hi Gaston
::
:: The missing tube would be 6K7. It might have had G or GT after the number. This determines the size and shape, electrically the same.
::
:: Since the radio wasn't made in the US Rider most likely doesn't have an exact schematic. Try 96X series. Where is says 6SQ7 you have 6Q7 and 6SK7 should be 6K7. These tubes serve the same purpose but do not have a top cap.
::
:: To change pages in Rider advance page number in the address.
::
::http://www.nostalgiaair.org/Riders/RCA.htm
::
::Norm
::
:::I forgot to add extra information
:::The radio has 5 valves but I was able to identify 4
:::this are:
:::25Z6GT
:::6K8GT
:::6Q7-G
:::25L6GT