The first Allwave 12 Deluxe

[Kent King]

When Scott first introduced the new Allwave Deluxe set, it really wasn't much different than the 1931 2-dial set with the newly developed rotating coil assembly. The tube lineup includes four 24A tubes (1st det and three IF tubes), four 56 tubes (osc, 2nd det and two AF stages) and a 51 (RF), plus the amplifier. The set does not have AVC: front panel controls are just a 3-position sensitivity control and a volume control that varies the IF bais. These sets were produced in the summer and fall of 1932, by December, the Allwave Deluxe with AVC (using a Wunderlich 2nd det) was being sold.

The non-AVC 12 is fairly rare, having only been produced for a few months. I have one in my collection and have only seen a very few others. I finally began restoring mine after the holiday. The first challenge was a schematic - there is not one published in any Scott literature. There is a schematic in the November 1932 Radio Craft magazine (with an article written by Scott). However, this diagram doesn't show a power supply and doesn't entirely match my non-AVC set (serial #A-229). So I set about drawing a diagram for my set and amp. These are attached, I'll upload some pics of the set soon.

Does anyone else have a non-AVC Allwave Deluxe?

Kent

And yes, this is the set that prompted my earlier question about the dual speaker system.

[Richard Sowry]

Mine is the AW-12 without AVC, with twin speakers.  This is my first Scott so I'm going to restuff everything.  It's kind of like the Philco Bakelite Blocks except they are rivetted in.  I will either replace with screws and nuts or pop rivets.  Thank you for your responses.

Dick

[David C. Poland]

Caution, the 3 larger bathtub caps across the rear apron of the Deluxe 12 tube receiver contain a coil. They are in the cathode circuits of the IF amp tubes - in Low stress circuits and I leave these 3 alone, unless there is a problem with cathode voltage issues.

Historically, the single dial 12 tube Scott Deluxe evolution:

- Introduced spring 1932 and initially had the same amp and single speaker as the 2-Dial. 8 pin Jones plug.

- Mid year 1934, revised adding the twin speaker and moved the big voltage divider from the amp to the receiver and receiver cable plug used only pins 1 to 5. Soon changed to 6 pin Jones plug.

- December1932, revised tube line up introducing the Wunderlich tube for full wave 2nd detector and AVC.

- Mid 1933, replaced the twin speakers with the 12 inch pedestal (a Jensen) with 2 field coils.

- Late 1933 or early 1934, revised audio path back to the amp and used pin 6 of the receiver cable plug.

I have had all these variations over the years. Scott was a custom set builder, chasing performance.

[David C. Poland]

Richard - you get that Scott Deluxe from Barry? 

[Richard Sowry]

Yes I did.  He said he had it for some time in his living room and was never going to get to restore it so he sold it.

[mike hadley]

As Dave mentioned earlier the larger bathtub caps have a cap and a coil, they are riveted to the rear apron and once removed you will see that the backs are soldered on, here is a photo from one removed from an allwave fifteen with the back cover removed, yes a later radio but does share a lot of similar components

the coil is to the right of the bathtub and the capacitor is to the left, a modern 630v polypropylene is a nice fit, be careful not to break the fine wire from the inductor as this is easy to do especially as they are full of tar.

The capacitor is grounded by the lead being trapped between the bathtub case and the tinplate back when it is soldered on, the coil capacitor junction is to the top left of the photo, if memory serves me correctly this terminal is marked on the case with a red dot.

[Richard Sowry]

The caps along the back apron on this receiver aren't very big.  They are .1MFD with a 3k resistor in parallel.  They aren't any bigger than the other bathtub caps in the rest of the receiver.  Do these still have the coil in them?

Thanks

Dick

[Kent King]

Probably not...I think the early AW12 just had an R/C circuit there for the cathode bypass.

Kent

Richard Sowry said:

The caps along the back apron on this receiver aren't very big.  They are .1MFD with a 3k resistor in parallel.  They aren't any bigger than the other bathtub caps in the rest of the receiver.  Do these still have the coil in them?

Thanks

Dick

[Richard Sowry]

Thanks Kent.  I'm a little leery about all the mica caps in this thing.  They are Micamold brand and I've always heard that they are really paper.  What is this forum's opinion?  I opened one up not too long ago and it was mica but that was just one and the people saying this are a lot more experienced than me.

  Also, this may be a stupid question but, I've changed all the rubber wire in the power supply amp section and restuffed all caps.  Can I power it up and check voltage at the output to the receiver or do the speakers have to be plugged in?  And is there any info as to what the voltage should be at the output?

Dick

[Kent King]

Dick -

Don't power up the amp without the tuner and speaker, the voltage on the first capacitor will go sky high and damage it. It must be run under load. The set B+ should be around 225-250 after the field and filters. Does you set have the divider resistor in the amp or in the tuner? If it's in the amp, it will run about 250, 150, and 125 at the taps. that's rough, but close enough. 

On the mica caps - I've hardly ever changed them, and never had problems with the MANY Scott sets I've restored. I get all the paper/wax caps, and the bathtubs, but never mess with the micamold caps.

Kent

[Richard Sowry]

Thank You very much Kent.  I don't want to damage anything so I will definitely wait till I restore all the components.  And I'll leave the micas alone.  Till I have another question. I thank you!!

Dick

[Alex R. Whitaker]

Micamold capacitors, in my experience, are usually mica.  If they are large then they're probably paper.  Military gear uses a lot of the paper ones, and there are some micamold paper caps in the Philharmonic (at least there were in the pointer dial one I restored several years ago), but they are large enough to give away what they are without looking at the schematic.  If there's a real question, look at the values on the schematic.  Usually, anything under 1000 pf (mmf) will be mica. 

[Richard Sowry]

Thanks Alex.  The problem is there are no values on the schematic. I've got information on the color codes of the mica caps if they follow the normal color codes of the times, meaning the 1920s and 30s.  I'm probably going to leave them alone anyway unless there is a serious problem getting it to receive.  Thanks again.

Dick