Allwave 15 in Tasman Cabinet Electrical Restoration

[Jon Ketron]

Several months ago I was able to purchase an AW15 housed in a Tasman cabinet.  This beautiful receiver is somewhat special as the tuner chassis is still riveted after all these years.  I picked up this set in Kansas City.  Quite a drive for me, the price was right and worth the effort.  The previous owner was a radio collector.  This AW15 and a poor condition AW23 were all he had left.  A very nice fellow, I asked were he picked up the set.  He stated the receiver had been in his possession for quite some time, purchased from another radio collector back in the 1990's in Wisconsin.

As to the riveted tuner chassis.  There is a cardboard sleeve located on one of the electrolytic cans. Learning from fellow Scott collectors and research, this cardboard sleeve signified a prior E.H. Scott repair, meaning this receiver was brought back to the Scott factory for repairs either during the 1930's or early 1940's.  These tuner chassis were originally riveted shut once they left the laboratory.  E.H. Scott offered a 5 year warranty on all his receivers.  The warranty would become void if someone removed these rivets or tampered with the set.  After this AW15 had it's repairs completed, the laboratory installed new rivets.  The tuner chassis has not been opened since.  A true time capsule.

What makes things even more interesting:  The antenna post set up would indicate this machine to be an early version AW15.  Dave Poland had mentioned the toggle switch on the far side looking at the back of the receiver was a two position tone control of sorts.  In place of the Wunderlich tube resides a #58 tube with grid cap lead.  The socket is not labeled with a number.  The Sensitivity control escutcheon shows 5 positions.  I can only turn the control three positions (will look into this further once chassis is opened).

My consensus would be this receiver either was a transition from early production to late production, or received these modifications once the receiver was brought back into E.H. Scott Laboratories for repairs.  I must note; there is a #450 inscribed on the inside of the power supply.  This too signifies prior E.H. Scott repair.  It is interesting to think about these variables as the AW15 model in general went through so many changes during it's year long production run.  I would greatly appreciate any input you might have on this matter.

I find it interesting that the 2A3 output tubes are of the Arcturus brand, test 90% percent emission with no shorts.  No way these could be original unless this set was not used often or these are replacement tubes.  I should have the results of the power supply shortly.

Jon 

[Jon Ketron]

[Jon Ketron]

Several modifications I want to point out.  Mike has already pointed out a very important modification we will get to soon.

The first modification I noticed is on the underside of the coil wheel.  There are two fine red colored felt strips in place.  I would imagine this modification was installed to help cut down on mechanical noise or clean the electrical contacts when changing bands?  The reason I have called this a modification, the early untouched AW15 version in Olympia cabinet I compeleted months ago did not have these two felt strips.  Was this a factory addition to the coil wheel for the AW23? 

Jon

[Jon Ketron]

Mike thank you for pointing this out.  We will investigate further very soon!

Jon
 
mike hadley said:

Jon;
Interesting to note that the bathtub filter to the right of the power umbilical (next to the antenna switch) only has the capacitor side connected and not the inductor, so this can't be wired as a filter, it will be interesting to see how this ties in with a schematic.
Looks like Scott has done it again!

Mike

[Jon Ketron]

Thank you for the advice Dave.  I too always wipe away with a damp disposable towel.  This stuff is indeed toxic.  I notice one of the bathtub caps has no corrosion.  Perhaps a different type of plating or metal all together?

Jon
 
David C. Poland said:

Jon - be careful with that powder coating on those bathtub caps. I always wipe away with damp paper towels and avoid direct skin contact - likely the harmful corrosion surface of cadmium coated metal.

[Norman S Braithwaite]

The felt strips are for cleaning the contacts.  I believe they were included on all AW23 coil wheels.  Your example is the first I have seen where the felt strips are not opposite each other.

Norman

[Thomas Day]

My all wave 23 coil wheel has two felt strips. They are placed between the contact strips opposite each other. 

[David C. Poland]

I seem to recall my AW-15's have the red felt pads to polish the silver contacts when changing SW bands. I know my AW-23's do.

Been too long since restoring my late 12 tube DELUXE AVC to remember.

[mike hadley]

My allwave fifteen has no felt pads, looking at the restoration photographs, there is no sign of any pre drilled holes either.

[mike hadley]

mike hadley said:

My allwave fifteen has no felt pads, looking at the restoration photographs, there is no sign of any pre drilled holes either, this is a real shame as I think that this is a excellent factory mod

[Jon Ketron]

Thank you all for your input and observations.  Mike, if remembered correctly, your AW15 is an early version with Wunderlich tube correct?  The last early version Wunderlich I completed did not have drilled holes or pads in place either.

Thanks to Norman's input on these "Potter" caps, we are able to gather these modifications could of very well taken place in 1936, during early run production AW23's that were utilizing such branded wax caps.  There are two present in this machine.  The first one up near the front of the chassis seems to have taken place of the old bath-tub cap that was once present.  The early version AW15 I completed several months ago had a bath-tub cap installed at this location.  I am having trouble reading the value of the cap.  I am thinking it is a .05 mfd.  Perhaps a .5 mfd?

[Norman S Braithwaite]

Jon:  A 0.5-mfd capacitor would be much larger than the one in your photograph.  I am quite sure it is a 0.05-mfd capacitor.

Norman

[mike hadley]

Jon:

Just had a look at the under chassis of my aw-15, the cap in this position is 0.05 mfd.

Mike