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
>
>
>
>
>
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|