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5th Aug 2005, 11:58 pm | #1 |
Dekatron
Join Date: Jan 2003
Location: Bradford on Avon, Wiltshire, UK.
Posts: 3,301
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CCH35 equivalent to 6K8G?
Hi all
Just finished another Emor globe. As received this odd set was fitted with a CCH35 in place of the 6K8G. Fair enough,some might say. And in most cases this would be fine. It actually worked, very well. The only trouble was that I received a nasty "tickle" from the metalising! Why? The designers had used pin 1 on the valve holder as a jump off point for the HT! Not a problem with a glass valve of course, but nasty if a metalised valve is used. The same thing would have happened with an ECH35/X61M etc. I will certainly check next time, and always before using a metalised F/C in place of the 6K8G!! Of course in sets designed for metallised valves, pin1 would be grounded. Mind how you go!! Last edited by Station X; 23rd Nov 2005 at 2:46 pm. Reason: Title made more meaningful. |
8th Aug 2005, 1:41 am | #2 |
Retired Dormant Member
Join Date: Apr 2003
Location: Blackpool, Lancashire, UK.
Posts: 4,061
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Re: CCH35 equivalent to 6K8G?
I've heard of this kinda thing before and if I remember correctly one of Chas Millers books makes reference to it and includes a warning of the inevitable hazards.
Without hunting round for the book and checking, as I recall it Chas implies this sort of thing with metalised valves is/was not uncommon Last edited by Station X; 23rd Nov 2005 at 2:47 pm. Reason: Title |
23rd Nov 2005, 12:40 pm | #3 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
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Re: CCH35 equivalent to 6K8G?
I had the same experience with my R1155 years ago. I had changed the original valves for metallised "equivalents",not realising that the spare pin on the holders had been utilised as an HT point! I ended up having to remove the metallising with sandpaper!
Jim Last edited by Station X; 23rd Nov 2005 at 2:47 pm. Reason: Title. |
24th Dec 2005, 4:46 pm | #4 |
Retired Dormant Member
Join Date: Feb 2005
Location: Monmouthshire,on South Wales border
Posts: 85
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Re: CCH35 equivalent to 6K8G?
THE CCH35 is not an equivalent to a 6k8.In a parallel fed heater line it will be underun since it has a 7.5v heater.If you have an AC/DC set it may be ok since its a 200 ma heater.
Its always better to use the correct valve |
24th Dec 2005, 8:05 pm | #5 |
Retired Dormant Member
Join Date: Mar 2003
Location: Birmingham, West Midlands, UK.
Posts: 785
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Re: CCH35 equivalent to 6K8G?
Some sets are surprisingly tolerant of having the wrong FC fitted - I once had a set which should have had a heptode 6A8 fitted when it had a triode-hexode 6K8 instead. Apart from some reduction in sensitivity it worked quite well, and I didn't realise that the wrong valve had been fitted until I got hold of the circuit diagram...
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