>From my point of view, it would be the etched markings that count.
It appears that they were put there by the manufacturers, and they ought to
know.
Comparing the data in the Philips/Mullard January 1970 databook for the
QE05/40 (6146A) and YL1370 (6146B) the differences are indeed minute.
There are no differences in the static curves, and only very small differences
in
input and grid-plate capacitances.
If you can measure heater current very accurately, the Philips/Mullard book
indicates that
the YL1370 (1,125 A) has 0,125 A lower heater current than the QE05/40 (1,25
A),
and this may give a clue.
Also, the weight of the YL1370 is 65g compared to the 57g of the QE05/40, maybe
due to
a sturdier bulb and plate, allowing a higher plate dissipation.
73/
Karl-Arne
SM0AOM
----- Original Message -----
From: "David C. Hallam" <DHallam@rapidsys.com>
To: <amps@contesting.com>
Sent: Tuesday, August 09, 2005 8:00 AM
Subject: [Amps] Fwd: 6146's
> I guess I should have phrased my question in more specific terms. Since
> these tubes are marked with two numbers, I am trying to figure out what I
> have. Are they really 6146A's as the branding indicates, or are they
> 6146B/6146W as the etching on the glass indicates? Any ideas?
>
> David
> KC2JD
>
> ------- Forwarded message -------
> From: "David C. Hallam" <DHallam@rapidsys.com>
> To: amps@contesting.com
> Cc:
> Subject: [Amps] 6146's
> Date: Mon, 08 Aug 2005 14:37:24 -0400
>
> I just acquired several 6146's with strange markings. They are General
> Electric branded and marked 6146A in ink or paint or whatever it is.
> However, etched in the glass some are marked 6146B or 6146W. Has anyone
> run across this before or know anything about it?
>
> David C. Hallam
> KC2JD
>
>
>
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