Will,
I am not too worried about the calibration. I am not doing anything that
requires traceability to any standard. It is just for my own use. I can
calibrate the meter myself close enough for my use.
I just was trying to find out if there are any significant differences
between the EA52 and EA53 that would kill the idea.
David
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
Behalf Of Will Matney
Sent: Tuesday, May 16, 2006 12:33 PM
To: amps@contesting.com
Subject: Re: [Amps] VTVM Diodes
David,
The tube type differences could be the gain, or voltages, I'm not sure. The
probes could possibly work, but those are the ones that used an acorn tube
in the tip aren't they? Here's the biggest problem. If you change the
tube(s), the meter will about sure be out of calibration. What happenes is
that as the meter was used from when it was new, the tubes gradually got
weaker while the meter was sent out once a year for calibration. Each time
it was re-calibrated, it was to the weaker tube signals. When you put a new
tube in that is 100%, it throws off the calibration. Solid state meters
don't do this to that extent. The yearly calibration for solid state I don't
think is needed. Maybe every three years, and that's if they're really used
a lot. However, if a solid state is repaired, it needs to be checked for
calibration then unless the part was out of the same batch as the original.
Even then, there's a possibility it could be off because of the gain
difference. The tube meters
though really need the calibration over shorter spans over the tubes gain
dropping over use. How much a new tube could throw it off, I'm not sure.
What you could do is measure some standards if you have them, and write down
the measured values. Really they don't have to be standards, just save the
original parts you used to test back for the last test. Compare these
measurements to the ones you get after you replace the tube, and adjust for
them.
Best,
Will
*********** REPLY SEPARATOR ***********
On 5/15/06 at 4:36 PM David C. Hallam wrote:
>I am trying to find an AC probe for my HP-410C. I have a probe from a USM
>116 VTVM. The 410C uses an EA53 diode in the probe and the 116 uses an
>EA52. From what I have found on the internet, these two tubes seem to be
>similar, base connection, heater voltage, frequency range, etc. Does any
>one know if I could use the probe from the USM 116 on the 410C?
>
>David
>KC2JD
>
>
>
>
>
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