Rodger Bean
¿ªÔÆÌåÓýAVO¡¯s 1, 2.5, 10 ranges look less cluttered to me (but then I am used to my AVO 8 Mk2 that I bought in 1965). The 1, 3, 10 sequence gives a visual ¡°beat¡± between the tick marks on the two scales. Going for an E-04 or higher sequence would make the scale even more cluttered. Another sequence was used by Sangamo Weston on the S68 series of dynamometers (voltmeter, ammeter and power), which was 10, 20 & 50 on the voltmeter. The scale on these is very cramped at the low end, the first two tick marks are 0 and 2. The distance between the 2 & 3 is approximately 12.5mm and between 9 & 10, 50mm. ? One aspect of the moving coil meter is that it averages fluctuations that are faster than the needle¡¯s response. Also, the inertia of the movement means that it acts as a low pass filter. I find trying to do a null adjustment with a digital display frustrating. In addition, a DMM used on the bench for nulling can suffer from its high input impedance, which makes it susceptible to stray pickup. I live within 5Km of six, high power AM stations (ERPs of 5 - 20KW). ? Regards Rodger Bean ? From: [email protected] <[email protected]> On Behalf Of Dr. David Kirkby, Kirkby Microwave Ltd
Sent: Monday, 22 August 2022 06:25 To: [email protected] Subject: Re: [Test Equipment Design & Construction] Optimal full scale deflection on analog meters: What would HP DO?? ? On Sun, Aug 21, 2022 at 12:10 PM, magnustoelle wrote:
Although the scales are marked 3.0 and 10 on the R&S instrument, I note that the full-scale on the 3 V range is 3.2 V. It looks to me as if the 10 aligns with sqrt(10)=3.16. I think if you assume your inputs are randomly distributed, you can't beat that if there is only one other scale between 1 and 10. |