Mw22-1 - UK Vintage Radio Repair and Restoration Discussion Forum

yagosaga · 8th Jun 2006, 7:46 am

Hello,

yesterday I have got a MW22-1 with 4 volts heating. I have tried to test it, but found no emission (between kathode and grid). Does somebody have some information about this valve? I have never seen a MW22-1 before. How old is it? How do I have to measure to find out whether it is still good?

Kind regards,
Eckhard

mickjjo · 8th Jun 2006, 9:14 am

Hi Eckhard, There is a PDF data sheet for the MW 22 -1 here if it helps:-

http://www.shinjo.info/frank/sheets/101/m/MW22-1.pdf

Regards, Mick.

FERNSEH · 8th Jun 2006, 10:47 am

The MW22-1 is used in the 1938 Pye 815 TV set, also the TV-radiogram version the 838.
As the data describes, the video drive requirement can be quite low, something like 15 p-p is sufficient to display a picture of good contrast.
In the Pye set the CRT grid is supplied direct from the full wave vision detector.
A 6.3 volt heater version was produced, the MW22-2. Some Pye 815 receivers were fitted with this tube.

DFWB

FERNSEH · 8th Jun 2006, 1:23 pm

Quote:

Originally Posted by earlytv

A GE prewar TV the HM-225 used the MW22-2 but never can find a data sheet.

(http://www.earlytelevision.org/ge_hm225-226_manual.html)

Is only change from MW22-1 the 6.3 volt heater?

The MW22-2 has the hexode gun assembly like the 4 volt CRT and has the Ct8 side contact base.

A later tube, the MW22-3 has a simple triode gun assy and a 2 volt 1,2 amp heater. Could have been sourced from Mazda?

DFWB.

oldeurope · 9th Jun 2006, 7:38 am

Quote:

Originally Posted by FERNSEH

Hello Eckhard,
I remember testing the MW22-1 in my Pye 838. The CRT analyser indicated that the tube had no emission, in fact the tube displays a really bright picture.

DFWB.

Hi David, this is because of the high transconductance.
Normally the testers set the g1 to -30V or so. Than there can not be
a current. My tester has an adjustable g1. This is very usefull.
I had this problem with some monitor crt's, they need only 200V at g2
and -10V at g1.

But the methode putting 0...10V to g1 and measureing the current,
(uA !!!) must be possible.

Kind regards
Darius

FERNSEH · 9th Jun 2006, 1:02 pm

Hi Darius and Eckhard,
The attached image shows a really bright picture from the screen of the MW22-1 CRT which is fitted in my Pye 838.

Darius: Of course you are right about this high slope tube, the -30 volts supplied to control grid by the CRT tester will result in the tube being cut-off.

In the Pye receiver the first anode is supplied with 150 volts.

Regards,
David.

8th Jun 2006, 7:46 am	#1
yagosaga Retired Dormant Member Join Date: Mar 2005 Location: Braunschweig, Germany Posts: 208	Mw22-1 Hello, yesterday I have got a MW22-1 with 4 volts heating. I have tried to test it, but found no emission (between kathode and grid). Does somebody have some information about this valve? I have never seen a MW22-1 before. How old is it? How do I have to measure to find out whether it is still good? Kind regards, Eckhard

8th Jun 2006, 9:14 am	#2
mickjjo Rest in Peace Join Date: Jul 2004 Location: Dartford, Kent, UK. Posts: 1,661	Re: Mw22-1 Hi Eckhard, There is a PDF data sheet for the MW 22 -1 here if it helps:- http://www.shinjo.info/frank/sheets/101/m/MW22-1.pdf Regards, Mick.

8th Jun 2006, 10:47 am	#3
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Mw22-1 The MW22-1 is used in the 1938 Pye 815 TV set, also the TV-radiogram version the 838. As the data describes, the video drive requirement can be quite low, something like 15 p-p is sufficient to display a picture of good contrast. In the Pye set the CRT grid is supplied direct from the full wave vision detector. A 6.3 volt heater version was produced, the MW22-2. Some Pye 815 receivers were fitted with this tube. DFWB

9th Jun 2006, 1:02 pm	#6
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Mw22-1 Hi Darius and Eckhard, The attached image shows a really bright picture from the screen of the MW22-1 CRT which is fitted in my Pye 838. Darius: Of course you are right about this high slope tube, the -30 volts supplied to control grid by the CRT tester will result in the tube being cut-off. In the Pye receiver the first anode is supplied with 150 volts. Regards, David. Attached Thumbnails