I recently ran into a 1942-model Philco with all original tubes, except one, which was marked "M-R."

During the war, the U.S. Government shut down consumer electronics manufacture so that production could be shifted to weaponry. However, a trickle of tubes was allowed to be sold, marked M-R, for only maintenance and repair of existing consumer sets.

Question: were the M-R tubes ones that had been rejected by army/navy inspectors?

Also: were M-R tubes sold directly to the public, or did they have to be sold through a radio repairmen for a bona-fide repair?

I wonder if a reason for marking them "M-R" was to try to distinguish them from any tubes being diverted from JAN production to the black market?

Many questions.
Doug

Doug,
Just looked at the tubes from my 42-1008 and they're
a mixture of Philco and Sylvania, except the NOS 5Y4
from Gary, which is Cunnungham.

marv

:I recently ran into a 1942-model Philco with all original tubes, except one, which was marked "M-R."
:
:During the war, the U.S. Government shut down consumer electronics manufacture so that production could be shifted to weaponry. However, a trickle of tubes was allowed to be sold, marked M-R, for only maintenance and repair of existing consumer sets.
:
:Question: were the M-R tubes ones that had been rejected by army/navy inspectors?
:
:Also: were M-R tubes sold directly to the public, or did they have to be sold through a radio repairmen for a bona-fide repair?
:
:I wonder if a reason for marking them "M-R" was to try to distinguish them from any tubes being diverted from JAN production to the black market?
:
:Many questions.
:Doug
:

Doug

Alan Douglas had told us this meant maintenance and repair as you mentioned. I always felt they were Manufacturer Rejects. I have some marked as seconds.

I believe most didn't meet the full spec.

Norm

:Doug,
:Just looked at the tubes from my 42-1008 and they're
:a mixture of Philco and Sylvania, except the NOS 5Y4
:from Gary, which is Cunnungham.
:
:marv
:
::I recently ran into a 1942-model Philco with all original tubes, except one, which was marked "M-R."
::
::During the war, the U.S. Government shut down consumer electronics manufacture so that production could be shifted to weaponry. However, a trickle of tubes was allowed to be sold, marked M-R, for only maintenance and repair of existing consumer sets.
::
::Question: were the M-R tubes ones that had been rejected by army/navy inspectors?
::
::Also: were M-R tubes sold directly to the public, or did they have to be sold through a radio repairmen for a bona-fide repair?
::
::I wonder if a reason for marking them "M-R" was to try to distinguish them from any tubes being diverted from JAN production to the black market?
::
::Many questions.
::Doug
::