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 Help with STC 205 please.
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 Return to top of page · Post #: 1 · Written at 2:22:18 PM on 10 October 2015.
Redxm's avatar
 Redxm
 Location: Tamworth, NSW
 Member since 6 April 2012
 Member #: 1126
 Postcount: 466

Hi
I have an STC 205 (Jelly Mould) on the bench at the moment. There is a wax capacitor on the Cathode of the converter valve. Unfortunately the value has rubbed off. Every circuit I have found is illegible.

Would anyone know what value it should be. I guess it is either .1μF or .2μF going by the physical size.
It measures as .15μF out of circuit.

Also the converter valve fitted is a 6D8G. In the AORSM the first page says 6J8G, and the next page says 6K8G. Is the 6D8G an acceptable substitute, or should I find a 6J8G/6K8G?

The radio plays quite well at this stage, pre alignment, but the capacitor has to go as it has physical damage.

Thanks

Ben
 
 Return to top of page · Post #: 2 · Written at 3:04:29 PM on 10 October 2015.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6687

Every circuit I have found is illegible.

Mine is quite illegible, too, but when I zoom it up C13 reads ".1 MF".
 
 Return to top of page · Post #: 3 · Written at 5:14:10 PM on 10 October 2015.
Redxm's avatar
 Redxm
 Location: Tamworth, NSW
 Member since 6 April 2012
 Member #: 1126
 Postcount: 466

Thanks, seems to have done the trick. Pulling in 2WEB at Bourke in daylight. That would be about 500km line of sight.

Ben
 
 Return to top of page · Post #: 4 · Written at 6:32:46 PM on 10 October 2015.
MonochromeTV's avatar
 MonochromeTV
 Location: Melbourne, VIC
 Member since 20 September 2011
 Member #: 1009
 Postcount: 1182

Huh!

I have C13 as being .05 μF. I think you mean C15 which is .1 uf.

And yet again, another mistake by the AORSM! Look at page 347 of Vol. 7: STC 205 5-Valve D/W Radio Phonograph. Definitely not a Jellymould!

6D8G is a pentagrid, very much similar to a 6A8G. This valve was seldom used in Australian radios. The correct converter is a 6J8G.
 
 Return to top of page · Post #: 5 · Written at 6:48:01 PM on 10 October 2015.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6687

I think you mean C15

Probably. My version is almost illegible, but it's the cathode bypass nonetheless.
 
 Return to top of page · Post #: 6 · Written at 11:33:18 AM on 14 October 2015.
Robbbert's avatar
 Robbbert
 Location: Hill Top, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 2015

The value wouldn't be critical. Anything from 10n to 100n would be fine.
 
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