I have an old triode, 4-pin base, marked: "RCA Radiotron" and "US Navy CRC38064" on the
bakelite base. I suspect it is equivalent to an 864, but would like
confirmation. It's in a 2-tube Doerle type home-made regen receiver. The other
tube is a 30. I've been using 1.5 V for the filaments, which is too low for the 30,
and would be slightly high for the 864.

Rich

Hi,
The CRC number is the contract number if I remember correctly. It should have a "VT" number, which was how the Navy and Army identified most tubes, or at least tried to.

Have you tried putting the tube in the freezer for a few minutes so it becomes cold enought to get condensation on the envelope? If not, give it a try, as this should reveal a faint ghost of the old markings. I am assuming you have already tried to fog the tube by breathing on it, the freezer approach keeps the condensation fine enough to discern writing for a longer period.

:I have an old triode, 4-pin base, marked: "RCA Radiotron" and "US Navy CRC38064" on the
:bakelite base. I suspect it is equivalent to an 864, but would like
:confirmation. It's in a 2-tube Doerle type home-made regen receiver. The other
:tube is a 30. I've been using 1.5 V for the filaments, which is too low for the 30,
:and would be slightly high for the 864.
:
:Rich

I did try the fog method, but could see only a "4" etched on the glass envelope.
No VT- number visible. I have a good list of VT data. I will try the freezer method.
Tnx...

Rich

:Hi,
:The CRC number is the contract number if I remember correctly. It should have a "VT" number, which was how the Navy and Army identified most tubes, or at least tried to.
:
:Have you tried putting the tube in the freezer for a few minutes so it becomes cold enought to get condensation on the envelope? If not, give it a try, as this should reveal a faint ghost of the old markings. I am assuming you have already tried to fog the tube by breathing on it, the freezer approach keeps the condensation fine enough to discern writing for a longer period.
:
:
:
::I have an old triode, 4-pin base, marked: "RCA Radiotron" and "US Navy CRC38064" on the
::bakelite base. I suspect it is equivalent to an 864, but would like
::confirmation. It's in a 2-tube Doerle type home-made regen receiver. The other
::tube is a 30. I've been using 1.5 V for the filaments, which is too low for the 30,
::and would be slightly high for the 864.
::
::Rich

Hi Rich

I have an 864, marked on the glass, with U.S. Navy, CRC 38064 engraved into the base. Your tube is an 864.

Normm

:I did try the fog method, but could see only a "4" etched on the glass envelope.
:No VT- number visible. I have a good list of VT data. I will try the freezer method.
:Tnx...
:
:Rich
:
::Hi,
::The CRC number is the contract number if I remember correctly. It should have a "VT" number, which was how the Navy and Army identified most tubes, or at least tried to.
::
::Have you tried putting the tube in the freezer for a few minutes so it becomes cold enought to get condensation on the envelope? If not, give it a try, as this should reveal a faint ghost of the old markings. I am assuming you have already tried to fog the tube by breathing on it, the freezer approach keeps the condensation fine enough to discern writing for a longer period.
::
::
::
:::I have an old triode, 4-pin base, marked: "RCA Radiotron" and "US Navy CRC38064" on the
:::bakelite base. I suspect it is equivalent to an 864, but would like
:::confirmation. It's in a 2-tube Doerle type home-made regen receiver. The other
:::tube is a 30. I've been using 1.5 V for the filaments, which is too low for the 30,
:::and would be slightly high for the 864.
:::
:::Rich

Thanks to both of you. It is an 864. I've been able to see
the etched number in reflected sunlight. It's faint, but it's
there. I am amazed that anyone would engrave the contract number
onto the bakelite base. From my days at Westinghouse, we merely
had to put the contract number on the individual boxes. I wonder
if this indicates a manufacture date around 1938?

Rich

:Hi Rich
:
: I have an 864, marked on the glass, with U.S. Navy, CRC 38064 engraved into the base. Your tube is an 864.
:
:Normm
:
::I did try the fog method, but could see only a "4" etched on the glass envelope.
::No VT- number visible. I have a good list of VT data. I will try the freezer method.
::Tnx...
::
::Rich
::
:::Hi,
:::The CRC number is the contract number if I remember correctly. It should have a "VT" number, which was how the Navy and Army identified most tubes, or at least tried to.
:::
:::Have you tried putting the tube in the freezer for a few minutes so it becomes cold enought to get condensation on the envelope? If not, give it a try, as this should reveal a faint ghost of the old markings. I am assuming you have already tried to fog the tube by breathing on it, the freezer approach keeps the condensation fine enough to discern writing for a longer period.
:::
:::
:::
::::I have an old triode, 4-pin base, marked: "RCA Radiotron" and "US Navy CRC38064" on the
::::bakelite base. I suspect it is equivalent to an 864, but would like
::::confirmation. It's in a 2-tube Doerle type home-made regen receiver. The other
::::tube is a 30. I've been using 1.5 V for the filaments, which is too low for the 30,
::::and would be slightly high for the 864.
::::
::::Rich