Lets not forget deci.


Sent from K5JLR


-------- Original message --------
From: Gedas <w8bya@...>
Date: 08/25/2018 9:03 AM (GMT-06:00)
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8656B


Hi Brian, do you remember from a long time ago when a 8pF cap would be
labeled as a 8 mmF on the schematic.

Gedas, W8BYA

Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

On 8/25/2018 2:54 AM, Brian wrote:

Hello Dave,

?

I think that avoiding use of mF is for the reason that a long time
ago, ie, when I was young, a capacitor marked 8 mF was known to be 8
microFarad. The use of uF is a Johnny come lately, with the emergence
of SI multipliers. Easy to write the Greek mu, but not so easy to type
on the early QWERTY keyboards with early versions of word-processing
software. So, rather than confuse older people, the multiplier m for
capacitance is generally avoided.

?

73 de Brian, VK2GCE

?

*From:*[email protected]
[mailto:[email protected]] *On Behalf Of *Dr.
David Kirkby from Kirkby Microwave Ltd
*Sent:* Saturday, 25 August 2018 3:40 PM
*To:* [email protected]
*Subject:* Re: [HP-Agilent-Keysight-equipment] HP 8656B

?

On Fri, 24 Aug 2018, 06:38 Kuba Ober, <kuba@...
<mailto:kuba@...>> wrote:

How big is that cap, size-wise? It’s unlikely to be a
supercapacitor for such voltage in anything older than a few years
or so, I’d bet. It’s a typo in the PL, and a common use of M for
micro. Happens all the time. You’re looking at 24,000uF @ 40V.?

?

It is strange why mF? are rarely used. We use mV, mA, m ohm, mH, mm,
but when it comes to capacitors one uses? fF, pF, nF, uF and farads,
but rarely mF.?

?

A capacitor of 0.022? F is rarely called 22 mF, but usually 22,000 uF.?

?

When I use my HP 4284A LCR meter, I have to stop and think when it
shows a result in mF.?

?

I can only guess at one time capacitors usually had values of less
than 1000 uF, so people used uF, and never changed

?

We don't tend to use Mm either. A distance would normally be quoted as
4000 km rather than 4 Mm.?

?

Dave.?

Hi Brian, do you remember from a long time ago when a 8pF cap would be labeled as a 8 mmF on the schematic.

Gedas, W8BYA

Gallery at 
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

Hello Dave,

?

I think that avoiding use of mF is for the reason that a long time ago, ie, when I was young, a capacitor marked 8 mF was known to be 8 microFarad. The use of uF is a Johnny come lately, with the emergence of SI multipliers. Easy to write the Greek mu, but not so easy to type on the early QWERTY keyboards with early versions of word-processing software. So, rather than confuse older people, the multiplier m for capacitance is generally avoided.

?

73 de Brian, VK2GCE

?

From: [email protected] [mailto:[email protected]] On Behalf Of Dr. David Kirkby from Kirkby Microwave Ltd
Sent: Saturday, 25 August 2018 3:40 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8656B

?

On Fri, 24 Aug 2018, 06:38 Kuba Ober, <kuba@...> wrote:

How big is that cap, size-wise? It’s unlikely to be a supercapacitor for such voltage in anything older than a few years or so, I’d bet. It’s a typo in the PL, and a common use of M for micro. Happens all the time. You’re looking at 24,000uF @ 40V.?

?

It is strange why mF? are rarely used. We use mV, mA, m ohm, mH, mm, but when it comes to capacitors one uses? fF, pF, nF, uF and farads, but rarely mF.?

?

A capacitor of 0.022? F is rarely called 22 mF, but usually 22,000 uF.?

?

When I use my HP 4284A LCR meter, I have to stop and think when it shows a result in mF.?

?

I can only guess at one time capacitors usually had values of less than 1000 uF, so people used uF, and never changed

?

We don't tend to use Mm either. A distance would normally be quoted as 4000 km rather than 4 Mm.?

?

Dave.?

Hello Dave,

?

I think that avoiding use of mF is for the reason that a long time ago, ie, when I was young, a capacitor marked 8 mF was known to be 8 microFarad. The use of uF is a Johnny come lately, with the emergence of SI multipliers. Easy to write the Greek mu, but not so easy to type on the early QWERTY keyboards with early versions of word-processing software. So, rather than confuse older people, the multiplier m for capacitance is generally avoided.

?

73 de Brian, VK2GCE

?

From: [email protected] [mailto:[email protected]] On Behalf Of Dr. David Kirkby from Kirkby Microwave Ltd
Sent: Saturday, 25 August 2018 3:40 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8656B

?

On Fri, 24 Aug 2018, 06:38 Kuba Ober, <kuba@...> wrote:

How big is that cap, size-wise? It’s unlikely to be a supercapacitor for such voltage in anything older than a few years or so, I’d bet. It’s a typo in the PL, and a common use of M for micro. Happens all the time. You’re looking at 24,000uF @ 40V.?

?

It is strange why mF? are rarely used. We use mV, mA, m ohm, mH, mm, but when it comes to capacitors one uses? fF, pF, nF, uF and farads, but rarely mF.?

?

A capacitor of 0.022? F is rarely called 22 mF, but usually 22,000 uF.?

?

When I use my HP 4284A LCR meter, I have to stop and think when it shows a result in mF.?

?

I can only guess at one time capacitors usually had values of less than 1000 uF, so people used uF, and never changed

?

We don't tend to use Mm either. A distance would normally be quoted as 4000 km rather than 4 Mm.?

?

Dave.?

From: Adrian <Adrian@...>
Sent: Aug 25, 2018 4:22 AM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8656B

So I am of an age that I grew up using Imperial measures and pre-decimal money. I have also lived and worked both sides of the Atlantic and in most things I am almost bi-lingual!

The one thing that still trips me up (if I'm not careful) is that in the States, in an engineering shop, a request to "take a couple of mil off that face" means they would take off two thousandths of an inch but in a UK shop they would take a couple of millimetres off!

In the UK 1/1000 of an inch is a 'thou', so I guess the use of 'mil' is a hangover from the Roman occupation of North America?

Adrian

?