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 Stromberg Carlson 601 , AC/DC radio
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 Return to top of page · Post #: 1 · Written at 3:50:49 AM on 19 June 2016.
Viccadillac's Gravatar
 Location: Perth, WA
 Member since 7 May 2012
 Member #: 1140
 Postcount: 152

Hello members,

I have repaired the above radio but initially I only was receiving noise . After extensive research I found the oscillator was not working . The 6J8 valve tested ok but when I replaced it with a better one the set came to life . After a bit of testing I have found the voltage across the heater terminals on the 6J8 read 3.4v and should be around 6v. If I pre heated the lower emission valve and plugged it in , the set worked and then as the valve cooled it stoped working.
The heater does glow but not brightly. I can't find anything wrong so I even changed the position of the heater from 1st to last in the series chain but it still only read 3.4v. The other valves had the correct 6v across the heater.

So am I missing something here or is this an inherit thing with this set. Works fine with a high emission valve but still has low heater voltage to the 6J8 valve. Everything else in the set is at correct voltage . So are there any thoughts on this or has anybody experienced this thing before.

Many thanks
Vic


 
 Return to top of page · Post #: 2 · Written at 8:41:14 AM on 19 June 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 5830

In a series heater chain, in order for the correct voltage to appear across each heater they each have to draw the same current -- typically 300mA.

Sounds like the heater of the 6J8 in question is no longer the correct resistance value.


 
 Return to top of page · Post #: 3 · Written at 10:31:58 AM on 19 June 2016.
Robbbert's avatar
 Location: Sydney, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1303

There are 2 kinds of 6J8:

6J8G with a 300mA heater, and 6J8GA with a 450mA heater. For a series chain you need the correct type that matches the current needed by the other valves in the chain. If a dial lamp is in the chain, it also needs to draw the same current.

Since you didn't specify the other valves, we can only assume they take 300mA (as GTC said).


 
 Return to top of page · Post #: 4 · Written at 1:58:08 PM on 20 June 2016.
Viccadillac's Gravatar
 Location: Perth, WA
 Member since 7 May 2012
 Member #: 1140
 Postcount: 152

There are 2 kinds of 6J8:

Thank you for the experience here guys. The valve line up in the set is , 6J8G , 6U7G , 6B6G , 25L6G , 25Z6G , 6U5.

Since the last post the radio is restored and working fantastic. The 6J8G was the fix. Simple solution to a complex problem .

Thanks for all the help. The biggest challenge awaits , I have to construct a drive arrangement for the dial.

Cheers
Vic


 
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