[Milsurplus] Frustrating BC-639 problem Solved

[J. Forster]

Rob,

You are saying 9002s from different makers have different pinouts?

Very odd,

-John

======================


> Hello,
>
> I've been beating my head against a newly-acquired BC-639 VHF receiver.
> Despite all DC parameters looking ok like the grid bias resistor testing
> ok, plate resistor ok, the local oscillator would not oscillate.  The
> tuned circuit checked out with grid-dip meter.  No plate current.
>
> I don't know what made me check, but in the process of figuring out what
> pin to inject some LO from an external source, I decided to take a look at
> the tube.  Despite the diagram in the manual and the one in my 1949 ARRL
> handbook showing both pins 2 and 7 of the 9002 being connected to the
> cathode, the Raytheon tube I am using has pin 2 connected to the getter.
> The receiver uses pin 2 only to connect to the cathode.  No wonder I was
> getting nothing.
>
> I ran a fine wire from pin 2 to pin 7, wrapped around the tube pins, put
> it back in and now the LO works.
>
> Go figure
>
> RF
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