Re: {Collins} Very strange problem discovered during LAB alignmentonKWM-2 RE



Would that indicate that there is some wavelength of radiation from the fluorescent lights that affects the polystyrene nose piece on the probe? Do you always have the probe grounded when working on the low scale? That would seem to be the only difference when you are using the T.

David
KW4DH

On 7/7/2011 10:49 AM, Jerry O. Stern wrote:
Is it only with light exposed diodes?  I found WILD VARIABILITY of the RF
voltage probe in both of my HP 410's (one tube one SS) when measuring on the
lowest scale (0 - 0.5 VAC) if I have any fluorescent workbench lamp too
close (even a few feet).  I have see these lamps kick the probe up to half
scale on this low range.  I have several probes, standard and heavy
militarized and happens on all.  Only exception is when I plug them into the
T connector between the RF out and dummy load.  Many moons ago when I first
saw this, HP410 expert Ashley (KISS) said that's to be expected.

73 Jerry
K1JOS


-----Original Message-----
From: k7fm [mailto:k7fm@xxxxxxxxxxxx]
Sent: Thursday, July 07, 2011 8:44 AM
To: collins@xxxxxxxxxxxxx
Subject: Re: {Collins} Very strange problem discovered during LAB
alignmentonKWM-2 RE

If you are talking about the carrier level, be aware that clear diodes such
as the 1N34 are sensitive to light and exposure to light will change the
null.  For this reason, final null should be done with them covered as they
would be in operation.

I suspect this was the reason that early computer which used many diodes,
covered them with a phenolic case.

73,  Colin K7FM


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--
Before I came here I was confused about this subject.  Having listened to your lecture I am still confused. But on a higher level.
Enrico Fermi







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