British Physical Labs RM175-LZ II Megohmmeter - UK Vintage Radio Repair and Restoration Discussion Forum

trobbins · 16th Oct 2018, 12:24 am

This tester from circa 1966 is yet another old school beast that has been surpassed for ease of use by many a modern hand-held 'megger', but still retains lab grade functions like setting any DC test voltage from 0 to 1kV, and a sub microamp meter that goes down to 6pA FS to allow measurement to 5 tera-ohm (which beats the pants off my 2 giga-ohm megger).

It uses a nice resonant reactor voltage regulator to provide 1% internal voltage rails for 180-250Vac mains. The leakage current measurement is done with an EF37A differential amplifier.

Just another British Physical Labs instrument that I had waiting for some tlc (https://www.vintage-radio.net/forum/...d.php?t=149963).

Ciao, Tim

newlite4 · 16th Oct 2018, 9:22 am

Around 20 years ago, before a refit, we had around six Farnell TSV30T from the early '60s. The Volts and Amps meters on these were made by British Physical Laboratories, Radlett. Maybe they had a commercial arm to produce these items.
Neil

Herald1360 · 16th Oct 2018, 10:46 am

I wonder why the EF37As weren't ME1400s?

trobbins · 16th Oct 2018, 11:09 am

Argh, link to restoration doc - forgot to add that in the first post:
https://www.dalmura.com.au/static/BP...175-LZ%202.pdf

Ed_Dinning · 16th Oct 2018, 4:46 pm

Ah, yes BPL mirror scale moving coil meters. We used then exclusively at Reyrolle in a whole range of test sets with 50uA to 1mA sensitivities.
Quite a few were converted to "poor mans home made Avos"

Ed

M0FYA Andy · 16th Oct 2018, 5:02 pm

I thought the ME1400 was identical to an EF37A, just run at a different heater voltage?

A Mullard con-trick.

Andy

16th Oct 2018, 12:24 am	#1
trobbins Heptode Join Date: Oct 2009 Location: Melbourne Australia Posts: 901	British Physical Labs RM175-LZ II Megohmmeter This tester from circa 1966 is yet another old school beast that has been surpassed for ease of use by many a modern hand-held 'megger', but still retains lab grade functions like setting any DC test voltage from 0 to 1kV, and a sub microamp meter that goes down to 6pA FS to allow measurement to 5 tera-ohm (which beats the pants off my 2 giga-ohm megger). It uses a nice resonant reactor voltage regulator to provide 1% internal voltage rails for 180-250Vac mains. The leakage current measurement is done with an EF37A differential amplifier. Just another British Physical Labs instrument that I had waiting for some tlc (https://www.vintage-radio.net/forum/...d.php?t=149963). Ciao, Tim Attached Thumbnails

16th Oct 2018, 9:22 am	#2
newlite4 Octode Join Date: Nov 2003 Location: Bath, Somerset, UK. Posts: 1,805	Re: British Physical Labs RM175-LZ II Megohmmeter Around 20 years ago, before a refit, we had around six Farnell TSV30T from the early '60s. The Volts and Amps meters on these were made by British Physical Laboratories, Radlett. Maybe they had a commercial arm to produce these items. Neil __________________ preserving the recent past, for the distant future.

16th Oct 2018, 10:46 am	#3
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: British Physical Labs RM175-LZ II Megohmmeter I wonder why the EF37As weren't ME1400s? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

16th Oct 2018, 11:09 am	#4
trobbins Heptode Join Date: Oct 2009 Location: Melbourne Australia Posts: 901	Re: British Physical Labs RM175-LZ II Megohmmeter Argh, link to restoration doc - forgot to add that in the first post: https://www.dalmura.com.au/static/BP...175-LZ%202.pdf

16th Oct 2018, 4:46 pm	#5
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: British Physical Labs RM175-LZ II Megohmmeter Ah, yes BPL mirror scale moving coil meters. We used then exclusively at Reyrolle in a whole range of test sets with 50uA to 1mA sensitivities. Quite a few were converted to "poor mans home made Avos" Ed

16th Oct 2018, 5:02 pm	#6
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Re: British Physical Labs RM175-LZ II Megohmmeter I thought the ME1400 was identical to an EF37A, just run at a different heater voltage? A Mullard con-trick. Andy