R390A RADIO RESTORATION
May-July, 2016

My friend Gerald, K4NHN dug deep into his radio storage to retrieve three R390A chassis for me to use in restoring one back into service. The restoration required many parts from 2 donor chassis, plus a number of additional parts from Ebay sellers to get a nice Stewart-Warner manufactured R390A up and running. The particular chassis that I chose for restoration had been stored for a number of years and required quite a bit of cleaning to start with. So far, about 100 hours of time invested.

Two Views of the Dissassembly
The pictures only partially capture how dirty the chassis was before restoration.


Here a view of the dissassembly process. To restore/clean the radio it required removing
all the modules, leaving only the wiring harness in place on the main frame.


Here is a second view of the many parts. No turning back now.

 

The first step in the restoration was the removal of the R.F. module and taking it outside where the elaborate gear mechanism was cleaned/degreased of years of dried grease and grime. The cleaned mechanism was re-lubricated with a synthetic lubricant. Once the unit was cleaned and restored to smooth operation, it is a delight to watch this mechanical-digital marvel in mechanical engineering in operation.

 

Here is view of the 8 cam actuated bars that are operated by the mechanical gearing. The cams move the transformer slugs in and out of the RF and tunable IF stage transformers.

 

Here is a picture of the IF chassis which contained many "black beauties of death" paper capacitors. All these were replaced with modern mylar capacitors with higher voltage ratings. The IF module had the most capacitors that needed changing and was the most difficult to service. Also, once the radio was reassembled, I found the 2KC filter was defective. I found a good replacement on Ebay but replacing it was a real bear; it took almost 4 hours to complete the replacement. All the " black beauty" capacitors were replaced in the other modules as well.

 

Here is a picture of the underside master wiring harness.

 

Once cleaned and all the defective parts and missing parts replaced, it was time to re-assemble the radio and get all the control shafts in alignment for smooth operation.
Here are 2 pictures showing the front panel re-installation

 

Once all the restoration work had been completed, it was time to double check everything--then check again. After review, the radio was ready to plug into the electrical outlet and turn it on. It sprang to life!! Since this radio has modules from a number of different radios, it required quite a bit of re-alignment.
Here is a view of the restored underside.

Here is view of restored radio chassis top.
The Completed Restoration as of June 28, 2016.

100 Plus Hours of Time Required for Restoration