EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

Has anyone tried to substitute the wunderlich as fitted to the all wave sets,
I was thinking along the lines of an old tube base turned into an adaptor with a 3a5 that has its anodes connected together and heaters in series, this would plug in with no mods to the chassis,
I will probably be shot down in flames for suggesting this but if it works there is a whole lot more 3a5 / dcc90 tubes than wunderlich's out there

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Cant seem to edit end of 4th paragraph should read:

...glass envelope lacking internal supports that the shouldered glass type have ..."

David P,

Thanks for your reply.  I will email you. If you believe the later design with the 55 tube works better, I may consider modifying.  But I prefer not to change the set, but come up with a plugable substitute. Do you have the schematic of the later version with the 55 tube? 
David Dodgen
David C. Poland said:

Dave, - I suspect no tube will work as well as a Wunderlick in your AW-15 set.

The Wunderlich has a pair of co-plainer grids, connected to the ends of a last IF coil center tapped secondary in a push-pull type way. And the tube also functions as an audio amp of the detected audio signal by that tube.

The "strap pin to the 55 grid cap" approach is a stop gap solution to get the radio playing.

I have an AW-15 that was modified (by factory?) to use the 55 tube with minor wiring change and adding a grid cap wire from below. I think reception suffers compared to a later version AW-15 designed for the 55 tube which I also have. I have an unrestored early Wunderlick AW-15 which I look forward to being able to compare. The Wunderlich tube is in a low stress position in the radio, but in a globe type glass envelope lacking internal of a soldered type envelope is subject to damage if dropped.

FYI - I can supply a good used Wunderlich tube - tested for emissions in my early Supreme tester and also tried in a Wunderlick 12 Deluxe I have. If interested - dcp944@yahoo.com

Schematics are in the Scott Info Archive in the Set Folders. There are two different diagrams with the 55 2nd detector.

Kent

Thank You David and Kent for the information,

David Dodgen

I assume that the Wunderlich tube was a 2.5VAC filament tube. I do not know if there exists a data sheet that shows all the characteristics of the tube including its filament current requirements. I did find one newer tube type that is somewhat similar in that it is a triode tube with a single plate and two signal grids, but two separate cathodes. It is a 6AE7GT, which is a tube with a 6.3VAC filament. I don't know if anyone has ever tried this tube, but it would require adding a small 6.3VAC filament transformer if the receiver has no current existing 6.3VAC filament winding on its power transformer. A physically small filament transformer could likely be mounted underneath the chassis to hide it from view. The two cathodes could be tied together. It would take some experimentation to determine how to properly bias the tube for best operation.

The aesthetics of such a change might not meet with the approval of many fans however. If such a modification was to become permanent, it might be best to enclose the tube in a suitable chrome plated tube shield sufficient to completely cover it and blend in with the rest of the chassis.

Another aspect of such a change is availability of the 6AE7GT. I do not know if they are readily available. It is shown as a discontinued tube, so if not many were ever manufactured it may not be a suitable replacement for a Wunderlich tube.

The 55 tube would be the easiest modification and since it is already a proven modification and showed up in the later versions of the AW-15 it is likely the most accepted and approved modification.

Joe

Since this is such a hot topic - go to the archive, in the Miscellaneous folder - I just added the Scott factory notes on replacing the Wunderlich with a type 55 tube.

Kent

Joesph & Kent & David,

Thanks for the info.  After I get a Wunderlich and get my AW15 perking, Im going to try a substitution method. David are you interested in parting with a Wunderlich?  I sent you an email.

David Dodgen

As we do modifications to equipment, it helps to be aware of helpful items. I recently came across this set of adapter plates for tube type equipment at Antique Electronics Supply:

https://www.tubesandmore.com/products/covers-chassis-socket-hole-steel

There are some other sources for similar items at other vendors.

Have fun!

Joe

David P,

David I got your email and replied.  I also sent you money for the tube but not shipping.  Let me know what you need.

Thanks,

David D

David Dodgen said:

David P,

Thanks for your reply.  I will email you. If you believe the later design with the 55 tube works better, I may consider modifying.  But I prefer not to change the set, but come up with a plugable substitute. Do you have the schematic of the later version with the 55 tube? 
David Dodgen
David C. Poland said:

Dave, - I suspect no tube will work as well as a Wunderlick in your AW-15 set.

The Wunderlich has a pair of co-plainer grids, connected to the ends of a last IF coil center tapped secondary in a push-pull type way. And the tube also functions as an audio amp of the detected audio signal by that tube.

The "strap pin to the 55 grid cap" approach is a stop gap solution to get the radio playing.

I have an AW-15 that was modified (by factory?) to use the 55 tube with minor wiring change and adding a grid cap wire from below. I think reception suffers compared to a later version AW-15 designed for the 55 tube which I also have. I have an unrestored early Wunderlick AW-15 which I look forward to being able to compare. The Wunderlich tube is in a low stress position in the radio, but in a globe type glass envelope lacking internal of a soldered type envelope is subject to damage if dropped.

FYI - I can supply a good used Wunderlich tube - tested for emissions in my early Supreme tester and also tried in a Wunderlick 12 Deluxe I have. If interested - dcp944@yahoo.com

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