21-04-2012, 06:55 PM
If the radio still has a full compliment of screening cans then stick with the KTW61's else fit adaptor plates to take B9A skirted valve holders. You can then fit EF89's and though they have their own internal screen they look better with Black screening cans in my opinion. For KTW61's the original screening cans are so important and that includes the metal top caps to give full screening. Also the receiver should have a base plate but its fitting will cause all of your hard earned re-alignment to change, more so on the upper frequency bands. It is most certain that Marconi fitted a false plate with access holes for trimming, then after alignment the base plate was replaced with a blank one. You could fit a plate with access holes already made but where does one get the proper trimming tool? I have seen them in the services, made from paxolin tube with a box spanner style fitting at the end to loosen the core lock nuts. Down the inside of the tube was a paxolin rod with an aluminium end piece containing a slot for actual core adjustment. The arrangement enabled locking of the core nut without disturbing the position of the core. I guess a suitable tool could be manufactured. Just take care sliding out the wafer switch shaft and once removed DO NOT turn any of the switches, leave them set just as they are. The large 0.1uF waxies in some of the switch compartments must be changed.
