Modified Allwave 23 questions

[Troy Taylor]

Hello-

I just posted some questions about the Allwave 12 I bought last weekend and wanted to ask some questions about a second Scott radio I was offered, but turned down because I have some reservations about its degree of authenticity (it has obviously been modified), and whether or not it would be possible to restore it to it's original configuration.

The second radio is an Allwave 23 and I was all set to purchase it too, but then I took a look at the back of the cabinet and noticed the cover panel was attached with phillips-head sheet-rock screws.  I removed the screws and saw a large mystery box of components and modern wiring, and a terminal strip of wires going everywhere stuck in the bottom of the cabinet.  Some of the wires lead to a large MAGNAVOX speaker that had been shoved in there.  Obviously someone has removed the correct speaker and replaced it with this albatross substitute, and then created some sort of Frankenstein contraption to work around the electrical differences between the factory speaker and this substitute.  I do not have any pictures of this conglomeration, but it is definitely not original factory work, or the work of someone that shares my belief of the necessity of maintaining originality when working on vintage items.

Although it might be functional, or made to be functional, as-is, I am only willing to buy this radio if I discover it is possible to 'unmolest' it and return it to the correct configuration and components it would have had when built.

At the very least it will need a replacement speaker of whatever variety is correct for this radio.  (However, I do not know what kind of speaker this would be.)  Probably everyone wants these speakers for something, so I have little confidence in finding one, but if it is possible to do so, I will reconsider purchasing this radio if I can be sure it is restorable.  I would like to restore this radio correctly, but I have little interest in one that has been butchered in this manner if proper restoration is not possible.

Thank you and best regards-

Troy Taylor

[Thomas Day]

The difference between5z3 and 83v is the current capacity of the
tube. You should be ok if you use a variac. There are 2versioms of the 83. The 83 is a mercury vapor type. The 83vis a regular high vacuum type. Tubes are still available. I have a spare set. The 2A3's are now about $50.00 each.

[Norman S Braithwaite]

The 83V is indirectly heated whereas the 5Z3 is directly heated.  The EH Scott radio laboratory recommended replacing the 83V tube with a type 5Z3 on a temporary basis during WWII when 83V tubes were unavailable.  If you intend to use the AW-23 on a regular basis, you should find an 83V where originally used.

Norman 

[David C. Poland]

Troy-

- dial insert - your receiver has the additional (2nd) antenna post, so choose the "clear" one (not really clear, but has the shorter color bars). Change to this version plastic insert was one of several mid 1936 changes to the 7 knob AW-23 along with the new Super Shield antenna coupler, 2nd antenna post obsoleting the outboard antenna switch, ...

-The back & fiberglass may have been an attempt to make a sort of bass reflex cabinet. I agree, just remove it.

- tube numbers are embossed on the tube sockets. One rectifier is the 5Z3. The other is an 83V (NOT an 83).

Also, notice two fuses under the amp - check both are good and the correct value: the standard 4 amp fuse and the small mini fuse should be 3/4 amp.

- Likely the original speaker had a major problem (open field coil or badly torn paper cone). What you have may function well. I recognize your output transformer as evidently scavenged from the original speaker pedestal base. Your diagram is evidently a record of how to incorporate the original output transformer in using a replacement field coil speaker. But check that the speaker field coil resistance measures about 925 ohms.  Being the later 7 knob model, the speaker would have had the 19 ohm voice, and your scavenged output transformer designed to match that voice coil - so hopefully your speaker is 16 ohm and not 8 ohm.

-Do not power up your radio until you have verified  1) any replacement filter caps on the amp are recent and 2) there is evidence of extensive, recent replacement all the original wax/foil/paper caps throughout. Otherwise, perform an extensive replacement of caps using modern film caps in the tuner, except mica caps should be OK, , with modern 630 volt film caps before you power up with a Variac. And that includes the caps partly inside the 3 diode assemblies under the tunes chassis.

- get the amp diagram from the 1st of the 3 AW-23 Technical Service doc - Version 1 in the set folders. You want the one that shows the main speaker having a 19 ohm voice coil.

-From the photo of torn speaker cloth, looks like a side grill. That is the original speaker cloth - too bad. No repo cloth available of that pattern currently.  

-word of warning, before removing the inside coil wheel, set the band switch to the extreme counter clockwise (white band/ broadcast band) about 7 o'clock position. And do not move the band switch pointer shaft until the coil wheel is reinstalled.  Why - because it also operates a switch in the antenna coil can above and you do not want to damage that switch mechanism. Note the orientation of that wheel and do not lose the 2 springs and buttons that ride the coil wheel. See the Technical Service document, which you should acquaint yourself with.

- A worthy restoration project.

[David C. Poland]

- Looking at that diagram, the trio of resistors was likely to combine with your speaker's field coil to attain about the needed 925 ohms.

-Also, note from the diagram the inclusion of the high frequency speakers and you should do so on your work bench. The original speaker had a large power resistor and an arrangement to substitute the tweeter pair for that big resistor when the optional tweeters were used. You lack that resistor, so you need to use those tweeters when powering up the radio. They are in the bias circuit for the output tubes. 

-And yes, those 2A3's are by far the most  expensive tube in the Scott AW-23.

- Those two neon voltage regulators are in series. At set operating voltage, they should glow. Receiver front right.  NE-42  and a bit difficult to locate.

[David C. Poland]

 Troy - check out this other current AW-23 thread on this site:

                 http://www.antiqueradios.com/forums/viewtopic.php?f=1&t=326459 info

It is full of overview info, photos and highlighted diagram with really spot-on comments by Norman Braithwaite.

May seem long and involved, but worthwhile to refer to as you get acquainted with your own AW-23.

The AW-23 is a very sophisticated and well engineered radio. And it sounds great with a contemporary source like an FM tuner or CD player.

[Kent King]

Troy -

Take a look at ebay item #202180902748. The set is rough, but it has the speaker you need to complete your set. I'd consider buying it, using the speaker and parting out the remainder. 

Kent

[Troy Taylor]

Thank you Kent.  I have contacted the seller to ask about shipping, as they indicate 'local pickup only' in their ad and I am much too far away from Kansas to make that feasible.  I might have to keep waiting for an orphan speaker; the cost of this complete radio + shipping, even if the seller is willing to do that, is likely to exceed my budget at present.  I have located an original Scott speaker, not the correct one for my radio, that I will be inquiring about further when I can post some pictures.  Hopefully it will perhaps be of interest to someone in trade for the speaker I need myself.

[David C. Poland]

Troy - with regard to Scott speakers - caution - Scott speakers are specific to a given model  (except the Sixteen, 14 tube Masterpiece and early Phantoms using 6V6 output tubes did use the same version speaker with 2 fields and an octal plug on the cable.)

The 1930's were not like the 1950's when speakers usually had permanent magnet  and were standardized at 4 , 8 or 16 ohms.

Prior to WW2, most radio manufacturers used the field coil not only for the speaker magnetism but also as part of the high voltage power supply. The speaker field coil was part of the radio high voltage circuit and therefore tended to be unique to each model radio. In addition the speaker voice coil impedance also varied greatly. Over the years Scott speakers varied: 8 ohms, 19 ohms, 38 ohms and in addition the output transformer was attached to the speaker and was chosen to match speaker voice coil to the output tube requirements.

So - until such time as you obtain the correct Scott tagged 12 inch pedestal speaker, stick with what came with you AW-23 in as much as it appears to be a properly designed substitution.

[Troy Taylor]

Hello-

I had a chance to go through and sort/organize all the handwritten paperwork that accompanied this radio when I bought it.  One thing in the notes written by a former owner, probably in October 1948 assuming that all the notes were written around the same time as the only page with a date, stood out to me.  On two different pages he wrote "If 4A fuse keeps blowing, replace 83V with 5Z3 or 80".  My radio does indeed have this substitution made as mentioned above in a previous posting.  However, it is not entirely clear if the notes he wrote were specifically applied to my particular radio, since there was also paperwork for a radio with a different serial number. 

I have not attempted to power up this radio yet as it has not been re-capped yet, nor have I replaced the substituted 83V yet.  But I wanted to ask:

If a previous owner made this substitution of rectifier tubes "because the 4AMP fuse kept blowing", what might an alternative cause of this problem be?  I doubt that Scott recommended this idea as a solution, and there is no indication of the source in the notes.  But if that fuse actually did blow frequently, what should I be on the lookout for when beginning to restore this radio?

Thank you and best regards-

Troy Taylor

[Troy Taylor]

Troy Taylor said:

Hello-

I had a chance to go through and sort/organize all the handwritten paperwork that accompanied this radio when I bought it.  One thing in the notes written by a former owner, probably in October 1948 assuming that all the notes were written around the same time as the only page with a date, stood out to me.  On two different pages he wrote "If 4A fuse keeps blowing, replace 83V with 5Z3 or 80".  My radio does indeed have this substitution made as mentioned above in a previous posting.  However, it is not entirely clear if the notes he wrote were specifically applied to my particular radio, since there was also paperwork for a radio with a different serial number. 

I have not attempted to power up this radio yet as it has not been re-capped yet, nor have I replaced the substituted 83V yet.  But I wanted to ask:

If a previous owner made this substitution of rectifier tubes "because the 4AMP fuse kept blowing", what might an alternative cause of this problem be?  I doubt that Scott recommended this idea as a solution, and there is no indication of the source in the notes.  But if that fuse actually did blow frequently, what should I be on the lookout for when beginning to restore this radio?

Thank you and best regards-

Troy Taylor

[Scott Seickel]

The 83v has a very low voltage drop across it at rated current.  The 5z3 and the 80 have a much higher voltage drop and will decrease your B+ voltage notably. 

[Norman S Braithwaite]

During WWII, the 83V tube was hard to obtain.  EH Scott Radio Laboratories recommended using a type 5Z3 tube on a temporary basis if an 83V tube was not available.  Today we should use the 83V or with a socket adapter (or rebased) a 5V4 or 5AR4 tube.

Norman