Need advice on issues with my Knight Kit

[Tim D]

That schematic is going to go a long way toward getting help. I'd like to hear some expert opinions on adding 100 ohm screen stability resistors which should eliminate any arc'ing with the screen grid. (And maybe that is what happened here.) I'm not an expert in bias schemes, but it might be beneficial to put 10 ohm resistors on the OP 7189's cathodes to measure the currents. (Need expert opinions here because I wouldn't want to disturb the bias if this isn't the right thing to do here.)

Of course fixing the output transformer should be high on the list..... Maybe Heyboer <sp?> could rewind it?

 

[spliteye]

Heyboer is a good idea, having the originals rewound is probably the best solution. I'll have to ask them about pricing, I'm sure custom winds aren't cheap.

Out of curiosity, would a transformer such as this Edcor work for this amp? It has a 8.6k ohm primary, which seems to be in range for EL84 variants.

https://www.edcorusa.com/cxpp21-86k

Thanks guys,
Dan

 

[gadget73]

the trouble with any non-original transformer is that the HF properties are not liable to be the same. It may need some fiddling to make the thing stable. All possible to do, but if that sounds like a foreign language I'd suggest finding originals or having them duplicated.

 

[carver11]

Hello Dan, are you still around here?

 

[Tim D]

So its been about 2 years. I wonder how the OP made out with the transformer?

 

[Tom Bavis]

I picked up one of these amps at a yard sale for $5... both output transformers turned out to be open!

 

[Tim D]

I picked up one of these amps at a yard sale for $5... both output transformers turned out to be open!

Ouch. I have KU-45 and KU-45A Knight receivers. Three of the output transformers are open too. I think it's the same part number. It would be nice to know if he went with Heyboer. I might have to do the same.