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 

[Norman S Braithwaite]

Being that the detector tube socket is unmarked, the set is early and would have originally used the Wunderlich (NOT Wunderlick) tube. The replacement should be a type 55 tube, not type 58. Look for a type 55 tube where a type 58 tube should be located. The output tubes should be type 2A3 tubes, not type 2A5 tubes. Are they really type 2A5 tubes?

Norman

[Jon Ketron]

Norman, 

I will look for the type 55 within the set.  I have corrected my spelling.

Thanks

Jon
 
Norman S Braithwaite said:

Being that the detector tube socket is unmarked, the set is early and would have originally used the Wunderlich (NOT Wunderlick) tube. The replacement should be a type 55 tube, not type 58. Look for a type 55 tube where a type 58 tube should be located.

Norman

[mike hadley]

Jon,
I'm very envious of the chrome, looks to be in perfect condition.
Mike

[mike hadley]

Jon;

Lookng at the rivets on the back of your chassis, it looks like you may have the same tube grid filter setup as mine, three filter boxes anda separate cap and choke affair for the first tube,

it will be interesting to see what is really inside,

mike

[Norman S Braithwaite]

Jon, are the output tubes really type 2A5 tubes?

[Jon Ketron]

Thank you for bringing this to my attention.  Another typo on my part.  Both output tubes are type 2A3's.  I have corrected this typo within the text.

 
Norman S Braithwaite said:

Jon, are the output tubes really type 2A5 tubes?

[Jon Ketron]

Thanks Mike.  Once I am able to open up the tuner chassis we can cross reference.  I too am interested to see what lies within.

Jon
 
mike hadley said:

Jon;

Lookng at the rivets on the back of your chassis, it looks like you may have the same tube grid filter setup as mine, three filter boxes anda separate cap and choke affair for the first tube,

it will be interesting to see what is really inside,

mike

[Norman S Braithwaite]

Jon:  Thanks.  If the 2A3 tubes are of the flat plate variety, they are most likely original.  It appears that the receiver was well cared for and probably little used.  I would not be surprised if the 2A3 tubes are original.   I have found other Scott Allwave receivers that still retained their original output tubes.  If the 2A3 tubes have the more common "H" plate geometry, they are replacements for sure.

Norman

[Jon Ketron]

Norman, you bring up a great observation.  I will have to research further regarding variations of the 2A3 tube as I am not as familiar with them.  A picture of the 2A3's is posted above.  Are you able to tell which variation these are from the picture?

Jon

[Norman S Braithwaite]

Jon:  Those are flat plate versions.  Manufactures changed to the "H" plate version around the end of 1935.  Scott had changed tube suppliers from Arcturus to RCA during the run of Allwave Fifteen receivers.

Norman

[David C. Poland]

Jon - FYI -  There is evidence, that when a Scott radio was returned to the factory for service, that certain updates may be made to conform to current production.

That may explain the 3 position switch with the earlier 5 position escutcheon. The Wunderlich socket center button has a dark red color and no tube number I suppose to match the dark red Wunderlich tube base. You may find the original center tapped final IF transformer secondary with the ends wired separately to each of the two diodes in the 55 tube, or maybe not. A hole will have been drilled in the chassis for the 55 tube grid cap wire - in later post-Wunderlick production, that hole was sleeved with a brass grommet for the 55 tube grid cap wire, which brass grommet your set probably lacks. You may find the 1st detector tube changed from a 58 to a 57 or maybe a 2A7 and so on.

Ahhh -  hence the possible variations in actual sets compared to available factory diagrams and why it is useful to have available more than one diagram during a set restoration. My take is to conform to the actual set rather than trying to reverse older changes, especially with indication of factory made updates.

Wish you well with your AW-15 project. I, too, have what I believe is an updated Wunderlich to 55 tube set in my collection.

[Jon Ketron]

Thank you Norman.  I checked all the tubes in the set, no type 55 present anywhere.  All grid cap tubes presents are type 58 and one is a type 2A7.  Interesting!

Jon
 
Norman S Braithwaite said:

Jon:  Those are flat plate versions.  Manufactures changed to the "H" plate version around the end of 1935.  Scott had changed tube suppliers from Arcturus to RCA during the run of Allwave Fifteen receivers.

Norman