Marconi T.M.E. 20 B/I RF Bridge - UK Vintage Radio Repair and Restoration Discussion Forum

Chaparal · 5th Oct 2015, 3:37 am

Hi Gents,

I'm searching for some information about a

Marconi T.M.E. 20 B/I RF Bridge

Specs, description etc.

Maybe someone know this beast ?

Thanks
Peter

Chaparal · 5th Oct 2015, 2:59 pm

Inside

Chaparal · 5th Oct 2015, 7:37 pm

Some more info:

Function switch
- C - BAL / UN
- L - BAL / UN

Switches for C:
0 - 10 x 0.001 uF 0 - 10 nF
0 - 10 x 0.0001 uF 0 - 1000 pF
0 - 150 var. dial 0 - 0.0001 uF 0 - 100 pF

Resistance, var.: Fine Resistance Balance

Switches for R (mS):
0 - 10: x 100 mS
0 - 10: x 10 mS
0 - 10: x 1 mS
0 - 10: x 0.1 mS
0 - 10: x 0.01 mS

1 mS = 1 / 1000 Ohm

on top: terminals for "X" DUT

connectors from left to right zero ohms
(Impedance ??)

weight appr. 20 Kg

How to use ?

Peter

Radio Wrangler · 5th Oct 2015, 7:47 pm

It looks like it needs a signal source and a detector as companion boxes.

Nicely made with some components similar to the Marconi "Circuit Magnification Meter" of the same period.

David

Chaparal · 5th Oct 2015, 8:19 pm

Case looks like TF340 / TF517 etc
area appr. 1940 ??

TF1245 looks to new

HP

Dickie · 5th Oct 2015, 9:17 pm

I have a document that claims TME 20B/1 is part of "OA199A/2 RF Impedance Bridge Assembly" and can be found in the 1959 Marconi Instruments catalogue. Unfortunately I have no more info. than that. I will dig around a bit.

Chaparal · 5th Oct 2015, 11:17 pm

Some specs would help ;-)

Peter

trh01uk · 6th Oct 2015, 10:01 am

Peter,

very interesting this early bridge. I turned up a research paper here:http://www.researchgate.net/publicat...om_Temperature which is dated 1968, and mentions the use of the bridge at 100kHz and 10MHz. For the range 10MHz to 1GHz they used a General Radio 1602B bridge, so that suggests your bridge is only rated to 10MHz. And looking at the internal construction with those large micamolds, that sounds about right.

Of course the 1968 date is only the date of the research, and they would have used instruments they had to hand, which of course could easily be decades old even then. I suspect the 1940 date that someone else suggested is not far out.

Richard

Chaparal · 6th Oct 2015, 4:11 pm

Richard,
didn't find your paper / no access ;-(

But, I found a schematic from Bell Labs that shows there RF bridge prinzip,
and lookes similary to the TME20, I think ?

Peter

Chaparal · 10th Oct 2015, 6:04 pm

I forgot to say (posting 3)

1 mS means 1 Milli Siemens

(symbol S) is the unit of electric conductance, electric susceptance and electric admittance in the International System of Units (SI).

Herald1360 · 11th Oct 2015, 9:23 am

The mho (inverse ohm) as was, no less.

trh01uk · 11th Oct 2015, 10:02 am

Quote:

Originally Posted by Chaparal

Richard,
didn't find your paper / no access

Peter,

to access the paper you have to click on "preview" quickly before it takes you to the login/register page. You can read the whole paper in preview mode anyway.....

It doesn't actually tell you much though - since its not primarily about the bridge.

There are many papers about bridges available. It doesn't describe your particular bridge, but there is a historical paper about impedance measurements with particular reference to the General Radio Company that can be downloaded from here. That paper goes into many types of bridges, and no doubt your bridge will fit one of them.

Richard

5th Oct 2015, 3:37 am	#1
Chaparal Hexode Join Date: Apr 2007 Location: Wiesbaden, Germany Posts: 333	Marconi T.M.E. 20 B/I RF Bridge Hi Gents, I'm searching for some information about a Marconi T.M.E. 20 B/I RF Bridge Specs, description etc. Maybe someone know this beast ? Thanks Peter Attached Thumbnails

5th Oct 2015, 2:59 pm	#2
Chaparal Hexode Join Date: Apr 2007 Location: Wiesbaden, Germany Posts: 333	Re: Marconi T.M.E. 20 B/I RF Bridge Inside Attached Thumbnails

5th Oct 2015, 7:37 pm	#3
Chaparal Hexode Join Date: Apr 2007 Location: Wiesbaden, Germany Posts: 333	Re: Marconi T.M.E. 20 B/I RF Bridge Some more info: Function switch - C - BAL / UN - L - BAL / UN Switches for C: 0 - 10 x 0.001 uF 0 - 10 nF 0 - 10 x 0.0001 uF 0 - 1000 pF 0 - 150 var. dial 0 - 0.0001 uF 0 - 100 pF Resistance, var.: Fine Resistance Balance Switches for R (mS): 0 - 10: x 100 mS 0 - 10: x 10 mS 0 - 10: x 1 mS 0 - 10: x 0.1 mS 0 - 10: x 0.01 mS 1 mS = 1 / 1000 Ohm on top: terminals for "X" DUT connectors from left to right zero ohms (Impedance ??) weight appr. 20 Kg How to use ? Peter

5th Oct 2015, 7:47 pm	#4
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,858	Re: Marconi T.M.E. 20 B/I RF Bridge It looks like it needs a signal source and a detector as companion boxes. Nicely made with some components similar to the Marconi "Circuit Magnification Meter" of the same period. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

5th Oct 2015, 8:19 pm	#5
Chaparal Hexode Join Date: Apr 2007 Location: Wiesbaden, Germany Posts: 333	Re: Marconi T.M.E. 20 B/I RF Bridge Case looks like TF340 / TF517 etc area appr. 1940 ?? TF1245 looks to new HP

5th Oct 2015, 9:17 pm	#6
Dickie Octode Join Date: Sep 2004 Location: St. Albans, Hertfordshire, UK. Posts: 1,478	Re: Marconi T.M.E. 20 B/I RF Bridge I have a document that claims TME 20B/1 is part of "OA199A/2 RF Impedance Bridge Assembly" and can be found in the 1959 Marconi Instruments catalogue. Unfortunately I have no more info. than that. I will dig around a bit. __________________ Regards, Richard, BVWS member

5th Oct 2015, 11:17 pm	#7
Chaparal Hexode Join Date: Apr 2007 Location: Wiesbaden, Germany Posts: 333	Re: Marconi T.M.E. 20 B/I RF Bridge Some specs would help ;-) Peter

6th Oct 2015, 10:01 am	#8
trh01uk Octode Join Date: Nov 2010 Location: Ross-on-Wye, Herefordshire, UK. Posts: 1,652	Re: Marconi T.M.E. 20 B/I RF Bridge Peter, very interesting this early bridge. I turned up a research paper here:http://www.researchgate.net/publicat...om_Temperature which is dated 1968, and mentions the use of the bridge at 100kHz and 10MHz. For the range 10MHz to 1GHz they used a General Radio 1602B bridge, so that suggests your bridge is only rated to 10MHz. And looking at the internal construction with those large micamolds, that sounds about right. Of course the 1968 date is only the date of the research, and they would have used instruments they had to hand, which of course could easily be decades old even then. I suspect the 1940 date that someone else suggested is not far out. Richard

6th Oct 2015, 4:11 pm	#9
Chaparal Hexode Join Date: Apr 2007 Location: Wiesbaden, Germany Posts: 333	Re: Marconi T.M.E. 20 B/I RF Bridge Richard, didn't find your paper / no access ;-( But, I found a schematic from Bell Labs that shows there RF bridge prinzip, and lookes similary to the TME20, I think ? Peter Attached Thumbnails

10th Oct 2015, 6:04 pm	#10
Chaparal Hexode Join Date: Apr 2007 Location: Wiesbaden, Germany Posts: 333	Re: Marconi T.M.E. 20 B/I RF Bridge I forgot to say (posting 3) 1 mS means 1 Milli Siemens (symbol S) is the unit of electric conductance, electric susceptance and electric admittance in the International System of Units (SI).

11th Oct 2015, 9:23 am	#11
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Marconi T.M.E. 20 B/I RF Bridge The mho (inverse ohm) as was, no less. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O