Levell TM8 Millivoltmeter - UK Vintage Radio Repair and Restoration Discussion Forum

jdavis6809 · 9th Sep 2022, 12:57 pm

hello,

have Levell TM8 Microvoltmeter unable to test as not know how to set controls Z1 and Z2

Allso anyone with manual

Thanks

john davis UK

frsimen · 9th Sep 2022, 5:48 pm

I have a TM9 which seems to be a TM8 with some additional ranges. It has three zero set positions on the switch. Postions 2 and 3 are likely to correspond with your Z1 and Z2 positions. The TM9's position 1 is used for the mechanical meter pointer zero adjustment. The TM8 doesn't appear to make any provision for that setting.

The instructions for the zero setting on the TM9 go as follows:

1) Select centre zero, then select Zero 1. Adjust the meter front screwhead for a zero.

2) Select Zero 2. Adjust the Zero 2 control slowly until the pointer is on average at 0 on the centre zero scale. A small fluctuation will exist due to thermal noise voltages.

3) Select Zero 3. Adjust the Zero 3 control slowly until the pointer is on average at 0 on the CZ scale.

Step 2 is probably the one for Z1 and step 3 for Z2.

Paula

9th Sep 2022, 12:57 pm	#1
jdavis6809 Tetrode Join Date: Jun 2013 Location: Blackpool, Lancashire, UK. Posts: 51	Levell TM8 Millivoltmeter hello, have Levell TM8 Microvoltmeter unable to test as not know how to set controls Z1 and Z2 Allso anyone with manual Thanks john davis UK

9th Sep 2022, 5:48 pm	#2
frsimen Heptode Join Date: Jan 2011 Location: Croydon, London, UK. Posts: 773	Re: Levell TM8 Millivoltmeter I have a TM9 which seems to be a TM8 with some additional ranges. It has three zero set positions on the switch. Postions 2 and 3 are likely to correspond with your Z1 and Z2 positions. The TM9's position 1 is used for the mechanical meter pointer zero adjustment. The TM8 doesn't appear to make any provision for that setting. The instructions for the zero setting on the TM9 go as follows: 1) Select centre zero, then select Zero 1. Adjust the meter front screwhead for a zero. 2) Select Zero 2. Adjust the Zero 2 control slowly until the pointer is on average at 0 on the centre zero scale. A small fluctuation will exist due to thermal noise voltages. 3) Select Zero 3. Adjust the Zero 3 control slowly until the pointer is on average at 0 on the CZ scale. Step 2 is probably the one for Z1 and step 3 for Z2. Paula