[AMRadio] Tube ID

Larry Szendrei ne1s at securespeed.us
Mon Feb 24 15:10:40 EST 2014

On 2/24/14 2:09 PM, Donald Chester wrote:
> An often overlooked VR tube is the type 874. It was the original
> mass-produced gaseous regulator tube, rated for 75 volts, and dates back to
> the late 1920s, but can be found in equipment manufactured well into the
> post-WWII period. It is designed to draw up to 40 milliamps at minimum load,
> while the octal and miniature versions are rated for only 30 ma, allowing
> the 874  to regulate over a wider range of source voltages and output loads
> than the lighter duty VR-75 and its miniature equivalent .
The 874 is actually a 90V regulator, and can draw up to 50mA continuous D.C.
(from page 169 of my mid-1930s RCA tube manual; page with edition 
information is missing.)

They are used (for example) in the power supplies of my RAK and RAL 
shipboard regenerative receivers, which were designed around 1936.


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