PILOT LITTLE MAESTRO
|NOTES||The photograph in the book "Radio! Radio!" doesn't do the set
justice. The small cabinet with deep coloured veneer with lighter inlay
looks most attractive. The gold coloured tuning scale also looks great,
an achievemnet really as in my opinion such scales usually look particularly
crap on other sets (Emerson spring to mind).
Have you totted up the total voltage needed for the valve heaters yet ? Yep it is low (68V) yet there is barely enough room for the octal valves let alone a mains transformer or super-hot mains dropper resistor. The answer ? Yep, the dreaded resistive mains lead. This particular set used a ~520R mains lead but with the added complication of a tapping point used to generate the H.T. supply. Nope, not complicated enough, I know, lets add yet another tap for the pilot lamp ! Presumably a different lead would need to be supplied for differing supply voltages ?
|SERVICE DATA||There is a copy of the service data covering all the Little Maestro models up to the mid 50's on CD#2.|
|CURRENT STATE||The woodwork is very nice, just a few minor scuffs to tart up (and which
the lighting seems to have really picked up in the photo). Some odd valve
replacements ; KT33C in the 25A6G's socket plus a U31 in the 25Z6G's socket.
Not suprisingly, the tapped resistive mains cord has been removed and even if it hadn't would almost certainly have not been servicable. The solution ? Well, the main voltage drop required is for the valve heater + pilot lamp chain and this can be achieved using a series capacitor - you can find details on how to select a suitable capacitor at www.vintage-radio.com.
The capacitor solution works well when driving a resistive load (such as valve heaters). However this is not an option for H.T. recifier circuits so the only option there is for a series resistor ; fortunately compared to teh valve heaters the required H.T. drop is fairly low and also a lower current so hopefully the power disipation wont be problem in the small crowded cabinet.
|WHERE FOUND||Liberated from the June 2003 Harpendon BVWS auction for £28.|
Now that's what I call compact !
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THE 1930's RADIO GALLERY
8th June 2003