That Darn 12X4 Tube

After installing the new 12X4 rectifier tube and powered up, the tube started arcing inside and there was a blue glow. I thought that the tube was bad so I had my tube supplier send another new tube. Same problem but this time the solid state vibrator died. So I decided to try a different vibrator from Aurora Design. This new vibrator is one bullet proof awesome chunk of engineering!! Installed it and everything works great!!

Old vibrator and new Aurora Design module

 Old vibrator gutted and ready for assembly

 New module soldered in the vibrator base

Base epoxied onto the can, ready for installation

Speaker Retrofit

I came up with a suitable solution for the speaker replacement. The original speaker was designed to fit into a very shallow box. This speaker is not made anymore and there is not direct replacement for it. I also could not find anyone who would recone it either. So I looked for another solution. I came up with mounting to small round speakers in the same space as the 4" x 6" speaker using a adapter plate I made.

Original 4" x 6" speaker mounted with #8-32 weld in studs

Cardboard template to make an adapter plate from

Template transferred to sheet metal

Sheet metal cut out

 

 Sheet metal mounting holes drilled and trimmed

 Speaker fitting

One of the two speakers

 

 Sheet metal marked for the speakers

 Pilot hole for the jig saw

 Speaker holes cut out

 Speakers test fitted on the sheet metal adapter plate.

 I used #4-40 flat head brass screws

 Test fit into the enclosure

Adapter plate painted flat black and speakers mounted

 

 I added some strip caulk to help reduce metal to metal vibration

All mounted and wired with strain relief. I also made a plug for the speaker to radio interface.

Finishing Up

More Rescuing

 Rebuild clutch installed

Tuning coils installed

 

 Installing re-capped electrolytic filter capacitor

 Re-installed tuner mechanism

 All new paper capacitors with "Orange Drops"

 Primered top and bottom covers

New tubes and solid state vibrator installed

Filter Capacitor Done & Tuning Coil Replaced

 I replaced the second tuning coil (far right) because the tuning slug was binding in the core. I got a new slug and coil from a chap on the Antique Radio forum.

 Base epoxied. The perferated piece holds the terminals in place.

 New Capacitors soldered in place

Filter capacitor assembled. I epoxied the base in place, epoxied the mounting ring and then crimped over the lip of the can.

Capacitors and Vibrator Ordered

I ordered all paper capacitors, electrolytics, and solid state vibrator.

Tuning Clutch, Cow Pasture

Soaking outer clutch plate in metal prep

Contact cement on inner clutch plate and clutch rubber

Painting outer clutch plate

Inner clutch plate with glued rubber

Ground down crimp on on the filter capacitor (cow pasture)

 

Mounting ring removed

Terminal plate removed

Removing filter cow pasture guts