TV22 Tube Position - UK Vintage Radio Repair and Restoration Discussion Forum

G3JZF_John · 29th Apr 2017, 4:42 pm

I have just replaced the tube in my BushTV22.The original developed an OC heater.

I have had some problems in getting the tube (MW 22-16) located correctly. I am assuming that the back clamp goes around the tube base say about 2mm from the glass. Can I then position the focus magnet relative to this or just leave it where it is?

A plan or photo from above would be useful, but I have not found one on the forum.

The set is working well, but I just wanted to get things right before putting it back in the cabinet.. Any help would be appreciated.

John

Dickie · 29th Apr 2017, 5:09 pm

This any help? This was my TV22 before restoration and looks much the same (only cleaner) after.

GeoffK · 29th Apr 2017, 5:20 pm

These picture may help. Worked on TV's once but not so much now.

G3JZF_John · 29th Apr 2017, 6:20 pm

Hi Guys

Many thanks for the photos etc.

My set seems a little different; there is a clamp for the tube that is not shown in your photos.

I will post a photo of mine tomorrow and I am sure we will then be able to sort it out.

Many Thanks

John

G3JZF_John · 29th Apr 2017, 6:34 pm

What I do notice is your the photos are of a later model...Mine has a PL38 line output valve and a different layout to the top deck. The chassis tag is "A6"

More later

John

GeoffK · 30th Apr 2017, 11:02 am

These links show the earlier TV22 Mk1

https://www.vintage-radio.net/forum/...=132338&page=2

https://www.vintage-radio.net/forum/...0&d=1483280146

https://www.vintage-radio.net/forum/...2&d=1483280146

Lloyd 1985 · 30th Apr 2017, 12:39 pm

I think there was a difference of the focus magnet assembly between models that used an MW22-18, and the MW22-16, the 16 being the one with the ion trap magnet. I'll see if I can dig up some photo's...

Regards,
Lloyd.

Lloyd 1985 · 30th Apr 2017, 12:59 pm

Here we go!

First pic shows the TV22 with an MW22-18 fitted, the bracket that carries the focus magnets is more of a U shape, with the tube neck clamp mounted quite far back.

Pic 2 shows the TV22 with an MW22-16 with ion trap, the bracket for the focus magnets is L shaped, and , I'm not 100% sure on this, so I'll check later, it looks like the tube neck clamp is on the back of the bracket, nearer the scan coils.

Hope this helps,

Lloyd.

G3JZF_John · 30th Apr 2017, 1:15 pm

Yes these sets seem to come in a variety of flavours.
Here are some photos which may help. There is a clamp where I think the ion trap should go. I could re-position it, but it was working with the tube I replaced.
One thing that would help me is to know the fore/aft position of the tube and if someone can measure, say the distance of the tube base from the chassis, I'd be pleased and could eliminate one variable.

Thanks all

John

G3JZF_John · 2nd May 2017, 3:50 pm

Thanks to all- Very useful.
Now realise that my set originally had an inline gun with no ion trap. See ref: https://www.vintage-radio.net/forum/...ad.php?t=52883
I solved the problem easily by reversing the tube clamp to give more room between it and the tube base' There is then space for ion trap to fit in the best position.

I can take another photo if anyone is interested.

I will probably do a soak test for a few hours before putting the back on and feeling very pleased with myself with another successful refurb.

THANKS GUYS.

John

Heatercathodeshort · 2nd May 2017, 6:34 pm

To get the best from the CRM93 I suggest that you use the correct ion trap for the Mazda gun. It usually has black and yellow sleeving over the pole pieces. With a bit of luck you may have one from the TMB272. The Mullard and Mazda ion trap gun assemblies differ considerably. The correct magnet will produce a much smoother adjustment being a lot less 'peaky'. John.

G3JZF_John · 3rd May 2017, 8:26 pm

John

Thanks for your post.
I am sorry that I not have been clear and indeed I have been somewhat confused myself but the tube I swapped from the TMB272 was not original and someone had fitted a Mullard MW22-16.
The ion trap came from another set and hopefully it's the one. When I have time I will try a couple or three different magnets and see if there are any differences.
The cabinet is in near showroom condition and I want to do it justice with a set that is working well.
I will take a few photos and will post them in the next few days,
John

29th Apr 2017, 4:42 pm	#1
G3JZF_John Retired Dormant Member Join Date: May 2011 Location: Sutton Coldfield, West Midlands, Uk. Posts: 78	TV22 Tube Position I have just replaced the tube in my BushTV22.The original developed an OC heater. I have had some problems in getting the tube (MW 22-16) located correctly. I am assuming that the back clamp goes around the tube base say about 2mm from the glass. Can I then position the focus magnet relative to this or just leave it where it is? A plan or photo from above would be useful, but I have not found one on the forum. The set is working well, but I just wanted to get things right before putting it back in the cabinet.. Any help would be appreciated. John

29th Apr 2017, 5:09 pm	#2
Dickie Octode Join Date: Sep 2004 Location: St. Albans, Hertfordshire, UK. Posts: 1,478	Re: TV22 Tube Position This any help? This was my TV22 before restoration and looks much the same (only cleaner) after. Attached Thumbnails __________________ Regards, Richard, BVWS member

29th Apr 2017, 5:20 pm	#3
GeoffK Heptode Join Date: Mar 2016 Location: Essex, UK. Posts: 602	Re: TV22 Tube Position These picture may help. Worked on TV's once but not so much now. Attached Thumbnails __________________ *Geoff*

29th Apr 2017, 6:20 pm	#4
G3JZF_John Retired Dormant Member Join Date: May 2011 Location: Sutton Coldfield, West Midlands, Uk. Posts: 78	Re: TV22 Tube Position Hi Guys Many thanks for the photos etc. My set seems a little different; there is a clamp for the tube that is not shown in your photos. I will post a photo of mine tomorrow and I am sure we will then be able to sort it out. Many Thanks John

29th Apr 2017, 6:34 pm	#5
G3JZF_John Retired Dormant Member Join Date: May 2011 Location: Sutton Coldfield, West Midlands, Uk. Posts: 78	Re: TV22 Tube Position What I do notice is your the photos are of a later model...Mine has a PL38 line output valve and a different layout to the top deck. The chassis tag is "A6" More later John

30th Apr 2017, 11:02 am	#6
GeoffK Heptode Join Date: Mar 2016 Location: Essex, UK. Posts: 602	Re: TV22 Tube Position These links show the earlier TV22 Mk1 https://www.vintage-radio.net/forum/...=132338&page=2 https://www.vintage-radio.net/forum/...0&d=1483280146 https://www.vintage-radio.net/forum/...2&d=1483280146 __________________ *Geoff*

30th Apr 2017, 12:39 pm	#7
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,820	Re: TV22 Tube Position I think there was a difference of the focus magnet assembly between models that used an MW22-18, and the MW22-16, the 16 being the one with the ion trap magnet. I'll see if I can dig up some photo's... Regards, Lloyd.

30th Apr 2017, 12:59 pm	#8
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,820	Re: TV22 Tube Position Here we go! First pic shows the TV22 with an MW22-18 fitted, the bracket that carries the focus magnets is more of a U shape, with the tube neck clamp mounted quite far back. Pic 2 shows the TV22 with an MW22-16 with ion trap, the bracket for the focus magnets is L shaped, and , I'm not 100% sure on this, so I'll check later, it looks like the tube neck clamp is on the back of the bracket, nearer the scan coils. Hope this helps, Lloyd. Attached Thumbnails

30th Apr 2017, 1:15 pm	#9
G3JZF_John Retired Dormant Member Join Date: May 2011 Location: Sutton Coldfield, West Midlands, Uk. Posts: 78	Re: TV22 Tube Position Yes these sets seem to come in a variety of flavours. Here are some photos which may help. There is a clamp where I think the ion trap should go. I could re-position it, but it was working with the tube I replaced. One thing that would help me is to know the fore/aft position of the tube and if someone can measure, say the distance of the tube base from the chassis, I'd be pleased and could eliminate one variable. Thanks all John Attached Thumbnails

2nd May 2017, 3:50 pm	#10
G3JZF_John Retired Dormant Member Join Date: May 2011 Location: Sutton Coldfield, West Midlands, Uk. Posts: 78	Re: TV22 Tube Position Thanks to all- Very useful. Now realise that my set originally had an inline gun with no ion trap. See ref: https://www.vintage-radio.net/forum/...ad.php?t=52883 I solved the problem easily by reversing the tube clamp to give more room between it and the tube base' There is then space for ion trap to fit in the best position. I can take another photo if anyone is interested. I will probably do a soak test for a few hours before putting the back on and feeling very pleased with myself with another successful refurb. THANKS GUYS. John

2nd May 2017, 6:34 pm	#11
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: TV22 Tube Position To get the best from the CRM93 I suggest that you use the correct ion trap for the Mazda gun. It usually has black and yellow sleeving over the pole pieces. With a bit of luck you may have one from the TMB272. The Mullard and Mazda ion trap gun assemblies differ considerably. The correct magnet will produce a much smoother adjustment being a lot less 'peaky'. John.

3rd May 2017, 8:26 pm	#12
G3JZF_John Retired Dormant Member Join Date: May 2011 Location: Sutton Coldfield, West Midlands, Uk. Posts: 78	Re: TV22 Tube Position John Thanks for your post. I am sorry that I not have been clear and indeed I have been somewhat confused myself but the tube I swapped from the TMB272 was not original and someone had fitted a Mullard MW22-16. The ion trap came from another set and hopefully it's the one. When I have time I will try a couple or three different magnets and see if there are any differences. The cabinet is in near showroom condition and I want to do it justice with a set that is working well. I will take a few photos and will post them in the next few days, John