This is my B600 I have in the shop. This was my first vintage radio that got me started with the Vintage radio obsession.
This chassis has been totally restored. There is currently a solid stage 1L6 and solid state 50A1 tube inside. I keep the original operational vacuum tubes separate and run this unit with the solid state tube versions.
I have cleaned the cabinet and kept its original vintage look. The only faults with the cabinet are the hair line cracks between the tone switches.
The B600 is a six tube radio that includes miniature tubes, the venerable 1L6 and 50A1 ballast tube. This radio was DOA. It played once the chassis was removed, the substitute ballast tube pins straightened and replaced and the phones jack was jumped with an alligator clip test lead. The Head phone jack needs attention with Emory cloth and contact cleaner or replaced.
Final set of pictures.
There are a few decisions to be made about this radio. The concerns are:
Oscillator Drop out
This radio is alleged to function down to 90 vac line voltage according to the service literature. (Note - The service Literature does not specify if all bands are to work at 90vac line voltage.) This explanation is located with the alignment table as found on: http://www.transoceanic.nostalgiaair.org/600/B600.pdf
The 50A1 Iron wire ballast tube is supposed to regulate the filament string current to 56ma +- 5ma. This tube has been substituted by what I can determine to be a fixed power resistor in a plastic tube. Restoring the 50A1 may rectify the drop out at less than US specified line voltage. And protect the 1L6 during over voltage conditions.
The 1L6 was replaced with a New Old Stock never used tube and the Oscillator dropped out at around 98 vac. My concern would be the over-current condition the substitute 50A1 allows in such an expensive tube to replace. It would be foolish to replace the 1L6 with out using a new 50A1 or a suitable Solid State current regulator.
One could legitimately argue the 50A1 is no longer needed in the U.S. with the quality of line voltage. Other models of the Transoceanic using the 1L6 does away with the 50A1. A power resistor replaces it. Personally I would use a Solid State current regulator. They last much longer than the 50A1s. It is not a matter if the 50A1 will burn out but when.
Restoration has been completed.
The cosmetics have been addressed. The leatherette cleaned and stained with black leather dye and preservatives, new brights applied to the knobs, replacement plastic dial scale (with markings), brass shined up and plastic treated with Novus #1 plastic polish.
The chassis performance is unchallenged. A NOS 1L6, a NOS D5TF30 (50A1) (in place of some fixed resistive substitute), full chassis restoration (caps and resistors), voltage dropping resistors compensated for a new 1N4007 diode, mechanical cleaning, new volume control, check on a battery pack, checked on a varriac down to 71vac and a complete alignment to burn-in to final alignment. It receives well on all bands.
See detailed performance results with a new D5TF30 (50A1) and 1L6 in this chassis here: http://www.ppinyot.com/50a1.htm I am particular about performance.
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