One of the many Champions

[Ed_Dinning]

Hi Folks, I have a Champion miniature set that is very like the Meteor in most aspects with L/M/S bands and the same chassis layout.
However it uses 12K8GT, 12K7GT, 12SR7 (no TC), 35L6, 35Z4. It appears to have used this line up from new as there are no sign of mods from the more usual 12SQ7 as DDT.
It had been working and then failed and was put to one side, so on returning to it I am head scratching.

My main query is on the aerial input circuits, mounted on the card back.
There is the usual tapped frame aerial that connects via 3 wires to the aerial coils (trader sheet) L2/4 & L3/5. There are also 2 SM caps mounted on the back and a series of 6 tags, one of which is the throw out aerial and the others that look as if a jumper wire and socket could be used with them.

Anyone got the schematic for this part of the set

Thanks, Ed

[Herald1360]

Originally Posted by Ed_Dinning

.....

However it uses 12K8GT, 12K7GT, 12SR7 (no TC), 35L6, 35Z4. It appears to have used this line up from new as there are no sign of mods from the more usual 12SQ7 as DDT.


.....

Thanks, Ed

The base connections for 12SQ7 and 12SR7 are the same though the SQ is a hi-mu triode and the SR a med-mu one. I suspect an SR bunged in instead of SQ would work OK-ish. Do the resistors around the triode tell any story? The GE datasheets for the valves in Franks electron tube data sheets give recommended values for operation at various voltages as a class A amplifier.



Other things being equal, the SR would be quite a bit lower in gain than the SQ.

[Ed_Dinning]

Hi Herald, no tell tales round the valvebase for the SR, so looks original. It could be that they had a few circuit mods depending on which valves were available.

I'm more interested in the aerial circuit and if there was a plug selection so a long wire could be used as well/ instead of the frame Ae

Ed

[ronbryan]

Is the aerial circuit in the earlier Champion Meteor (Trader Sheet 927, inset in centre of second page) any help? This has the tapped frame aerial for MW, band switch and two capacitors shown, one of which is the throw-out aerial isolating cap.

An alternative is the aerial circuit for the two band Planet (Trader Sheet 792), which has provision for an external aerial via two capacitors. A further alternative aaerial circit on the Planet is inset on the first page circuit diagram, where the frame aerial for MW has a coupling winding added.

Ron

[Ed_Dinning]

Hi Folks, this one appears to be a bit of a mix of circuitry, but the front end is working OK and I've found a 12Q7GT, so I'll convert it to the Trader Circuit

Ed