[R-390] 12be6

[Steve Hobensack]

    My SP-600 jx17 is finicky about the 6be6 mixer. Some seemingly good 6be6 
will not work. I wonder what passive component in the associated circuit 
might be getting out of spec ?
  ...Steve...N8YE

Message: 5
Date: Tue, 26 Jun 2007 15:19:02 -0400
From: "Tim  Shoppa" <tshoppa at wmata.com>
Subject: Re: [R-390] Tube testers
To: <r-390 at mailman.qth.net>, "Joel Richey" <richey2 at mindspring.com>
Message-ID: <46812E660200003700008CFE at gwiavs.nservices.wmata.com>
Content-Type: text/plain; charset=US-ASCII

W2DBO wrote:
>of em, they all tested good, took the rx outa the
>cabanit and grabed the voltmeter and check all plate
>and screen voltage everything looked good, worked
>on that radio for 3 days, the 4th day my Pop came up
>to me and handed me a box with a 12BE6 and said put
>this in and I said I had checked all the tubes and their
>are all good, I put the tube in and 45 seconds later
>it was playing

Seeing how the 12BE6 is a heptode and in a AA5 used
as both an oscillator and a mixer, not too surprising that
the tester got stumped by it :-).

Most likely it wasn't oscillating and the tester used
a grid not for oscillation for its test!

I was recently working on SPICE models for heptodes
and no tube book gives useful information for modeling.
Had to do some 3-dimensional curve tracing!

Tim.

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