Pre-SI units - Inductance? - UK Vintage Radio Repair and Restoration Discussion Forum

Arqiva BOC · 21st Feb 2017, 7:24 pm

Ive just received the vintage (1931) Admiralty wireless books, thanks to Pete G4AAW. Fascinating reading - right at the transition between spark, arc, alternator and new fangled valve radios!

But, im slightly lost with an obsolete unit -

can anyone tell me the conversion into Henries of inductances measured in 'mics' ?

Im reading a section in vol 1 on ships antenna tuned circuits, with a value of 15.8 mic-jars!

Ive managed to find out that 1 jar is about 1.2nF, but I cant find a conversion for mics!

Arqiva BOC · 21st Feb 2017, 7:36 pm

Ha! Ive found it! Theres a wavelength/frequency/oscillation constant table in an appendix - this reveals that its just as we would use it today - microHenries!

Som many wonderfully esoteric terms in these books - the British Phon, MSC (miles standard telephone cable) etc

Marvelous!

ms660 · 21st Feb 2017, 7:38 pm

You beat me to it, mag page 280:

http://www.americanradiohistory.com/...ld-1917-07.pdf

Lawrence.

Arqiva BOC · 21st Feb 2017, 7:41 pm

You've done it now! I have a small collection of circular calculators and slide rules - now I want a Davis-Martin Wireless slide rule!!!

ms660 · 21st Feb 2017, 7:44 pm

Lawrence.

Andrew B · 24th Feb 2017, 2:38 am

I enjoyed reading the magazine, thank you Lawrence

Brigham · 24th Feb 2017, 1:27 pm

You certainly got your tanner's worth!

21st Feb 2017, 7:24 pm	#1
Arqiva BOC Retired Dormant Member Join Date: Aug 2014 Location: Emley Moor, West Yorkshire, UK. Posts: 92	Pre-SI units - Inductance? Ive just received the vintage (1931) Admiralty wireless books, thanks to Pete G4AAW. Fascinating reading - right at the transition between spark, arc, alternator and new fangled valve radios! But, im slightly lost with an obsolete unit - can anyone tell me the conversion into Henries of inductances measured in 'mics' ? Im reading a section in vol 1 on ships antenna tuned circuits, with a value of 15.8 mic-jars! Ive managed to find out that 1 jar is about 1.2nF, but I cant find a conversion for mics!

21st Feb 2017, 7:36 pm	#2
Arqiva BOC Retired Dormant Member Join Date: Aug 2014 Location: Emley Moor, West Yorkshire, UK. Posts: 92	Re: Pre-SI units - Inductance? Ha! Ive found it! Theres a wavelength/frequency/oscillation constant table in an appendix - this reveals that its just as we would use it today - microHenries! Som many wonderfully esoteric terms in these books - the British Phon, MSC (miles standard telephone cable) etc Marvelous!

21st Feb 2017, 7:38 pm	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Pre-SI units - Inductance? You beat me to it, mag page 280: http://www.americanradiohistory.com/...ld-1917-07.pdf Lawrence.

21st Feb 2017, 7:41 pm	#4
Arqiva BOC Retired Dormant Member Join Date: Aug 2014 Location: Emley Moor, West Yorkshire, UK. Posts: 92	Re: Pre-SI units - Inductance? You've done it now! I have a small collection of circular calculators and slide rules - now I want a Davis-Martin Wireless slide rule!!!

21st Feb 2017, 7:44 pm	#5
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Pre-SI units - Inductance? Lawrence.

24th Feb 2017, 2:38 am	#6
Andrew B Heptode Join Date: May 2015 Location: Bradford, West Yorkshire, UK. Posts: 512	Re: Pre-SI units - Inductance? I enjoyed reading the magazine, thank you Lawrence __________________ worried about the electrons entering the circuit and the smoke leaving Andrew

24th Feb 2017, 1:27 pm	#7
Brigham Octode Join Date: Mar 2006 Location: Co. Durham, UK. Posts: 1,117	Re: Pre-SI units - Inductance? You certainly got your tanner's worth!