AR88LF Receiver. - UK Vintage Radio Repair and Restoration Discussion Forum

crackle · 19th Jul 2017, 8:16 am

hi
After my current restoration of the KB 428 I am thinking of starting on the AR88 LF.
One question I have is about the resistor units on the schematic diagram.
Here are some examples of how they are marked; 2.2 Meg, 1000, & 680 M.

The 2.2Meg and 1000 seem clear enough but what on earth is 680 M.

Thanks
Mike

ms660 · 19th Jul 2017, 8:24 am

680k.

Basically meg = megohm.

m = kohm

Lawrence.

Radio Wrangler · 19th Jul 2017, 8:45 am

It's a diagram from a different era. The term 'picofarad' wasn't used and you'll see mention of micro-micro-farads instead. Valves are drawn upside down.

David

crackle · 19th Jul 2017, 8:56 am

I thought it probably was, but why on earth M for Kohm.

Mike

ms660 · 19th Jul 2017, 9:16 am

Dunno, maybe using meg as a reference then using milli.....1,000th of a meg?

The "m" prefix isn't used in the AR77 schematic.

Lawrence.

turretslug · 19th Jul 2017, 10:19 am

Roman numeral "M", or 1,000x multiplier. From an era when everything Roman was drummed into children's heads at javelin-point. One of those things that turned up here and there before SI standardisation and 1,000x went Greek (kilo!).

ex seismic · 19th Jul 2017, 10:45 am

Indeed, as also seen here on the tacho of a 1946 MG.

Gordon

crackle · 19th Jul 2017, 11:39 am

I suppose that makes a tiny little sense.
Thanks guys
It all helps to understand and remember.
Mike

G6Tanuki · 19th Jul 2017, 11:56 am

BTW if you dig around on the VMARS site you can find an AR88 schematic that's been redrawn from the US style to the 1940s/1950s UK-military style - a lot more readable, at least the valves are the right way up!

Can't remember if the diagram there is for a D or a LF though....

Synchrodyne · 19th Jul 2017, 10:53 pm

Quote:

Originally Posted by turretslug

Roman numeral "M", or 1,000x multiplier. From an era when everything Roman was drummed into children's heads at javelin-point. One of those things that turned up here and there before SI standardisation and 1,000x went Greek (kilo!).

Indeed, and it seems that M was used quite widely for that purpose in the USA. An example (to illustrate the broad point without I hope veering too far off-topic) is the oil industry, with MBbl for 1000 barrels, (and MMBbl for one million barrels). Historically, M was also used by some in the railroad industry (e.g. Southern Pacific) to designate 1000 lb of trailing load. So, train weights were designated in Ms not tons. But I must admit that I hadn’t previously seen it used in electronics.

Cheers,

Jon_G4MDC · 20th Jul 2017, 6:50 pm

So isn't that a devalued English Million by the same amount as an English Billion?
I think it is...Or?

19th Jul 2017, 8:16 am	#1
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	AR88LF Receiver. hi After my current restoration of the KB 428 I am thinking of starting on the AR88 LF. One question I have is about the resistor units on the schematic diagram. Here are some examples of how they are marked; 2.2 Meg, 1000, & 680 M. The 2.2Meg and 1000 seem clear enough but what on earth is 680 M. Thanks Mike Attached Thumbnails

19th Jul 2017, 8:24 am	#2
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Ar88 lf 680k. Basically meg = megohm. m = kohm Lawrence.

19th Jul 2017, 8:45 am	#3
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,874	Re: Ar88 lf It's a diagram from a different era. The term 'picofarad' wasn't used and you'll see mention of micro-micro-farads instead. Valves are drawn upside down. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

19th Jul 2017, 8:56 am	#4
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Ar88 lf I thought it probably was, but why on earth M for Kohm. Mike

19th Jul 2017, 9:16 am	#5
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Ar88 lf Dunno, maybe using meg as a reference then using milli.....1,000th of a meg? The "m" prefix isn't used in the AR77 schematic. Lawrence.

19th Jul 2017, 10:19 am	#6
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,395	Re: Ar88 lf Roman numeral "M", or 1,000x multiplier. From an era when everything Roman was drummed into children's heads at javelin-point. One of those things that turned up here and there before SI standardisation and 1,000x went Greek (kilo!).

19th Jul 2017, 10:45 am	#7
ex seismic Heptode Join Date: Sep 2009 Location: Tonbridge, Kent, UK. Posts: 686	Re: Ar88 lf Indeed, as also seen here on the tacho of a 1946 MG. Gordon Attached Thumbnails

19th Jul 2017, 11:39 am	#8
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Ar88 lf I suppose that makes a tiny little sense. Thanks guys It all helps to understand and remember. Mike

19th Jul 2017, 11:56 am	#9
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Ar88 lf BTW if you dig around on the VMARS site you can find an AR88 schematic that's been redrawn from the US style to the 1940s/1950s UK-military style - a lot more readable, at least the valves are the right way up! Can't remember if the diagram there is for a D or a LF though....

20th Jul 2017, 6:50 pm	#11
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Ar88 lf So isn't that a devalued English Million by the same amount as an English Billion? I think it is...Or?