UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Television and Video

Notices

Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

Closed Thread
 
Thread Tools
Old 7th Jul 2019, 2:43 pm   #1
matspar
Pentode
 
matspar's Avatar
 
Join Date: Aug 2009
Location: Portsmouth, Hampshire, UK.
Posts: 230
Default Philips 492U aerial connectivity

Hello All,

I'm slowly restoring this 1949 Philips 492U. Coming along nicely and now at the point where I need to get out the Aurora and squirt a signal in. The set uses a balanced twin-feeder arrangement (no co-axial socket) and I haven't encountered a set with this arrangement for over 20 years.
Embarrassingly I have completely forgotten how to connect it up and I can't find any information on how to do this anywhere. Do I need a balance to imbalance transformer (which I do not possess) or is there another way?
Seem to remember making something up with 1000pf caps but it was all a long time ago.

Best regards
Matt
Attached Thumbnails
Click image for larger version

Name:	9.jpg
Views:	212
Size:	62.3 KB
ID:	186293   Click image for larger version

Name:	6.jpg
Views:	201
Size:	46.1 KB
ID:	186294   Click image for larger version

Name:	66398854_10162133890960220_8345425492567916544_n.jpg
Views:	191
Size:	91.0 KB
ID:	186295  

Last edited by matspar; 7th Jul 2019 at 2:51 pm.
matspar is offline  
Old 7th Jul 2019, 3:35 pm   #2
Pieter H
Tetrode
 
Join Date: Sep 2017
Location: Waalre, Netherlands
Posts: 67
Default Re: Philips 492U aerial connectivity

Hi Matt,

that is a very neat 492U you have! Would be interested in some more detailed pictures, also for my site on the early Philips TV history.

As to a 75 Ohm asymmetrical to 300 Ohm symmetrical converter, below is just one of the many examples you can find. I don't think it is very critical in this case. Attached is a schematic of the input of the 485U, which is the same as in the 492U, so you can tune the antenna out with C18 for maximum reception.

Cheers, Pieter
Attached Thumbnails
Click image for larger version

Name:	balunzcopy.jpg
Views:	145
Size:	43.2 KB
ID:	186304   Click image for larger version

Name:	Philips 1949 TG385 Front end.jpg
Views:	153
Size:	45.2 KB
ID:	186305  
Pieter H is offline  
Old 7th Jul 2019, 5:37 pm   #3
kan_turk
Hexode
 
kan_turk's Avatar
 
Join Date: Mar 2014
Location: Dublin, Ireland
Posts: 396
Default Re: Philips 492U aerial connectivity

75-300 ohm balun matching transformers are available very cheaply on ebay if you don’t wish to make up one yourself - the added advantage being that they come fitted with appropriate connectors for such as your application, that is if you get the appropriate one

Alternatively you can ground one side of the TVs input transformer and connect Aurora directly (assuming tv chassis is grounded, which I believe it is)
Attached Thumbnails
Click image for larger version

Name:	507B98FE-FF3F-4309-BFA1-47C516B48CE6.jpg
Views:	87
Size:	29.6 KB
ID:	186315  
kan_turk is offline  
Old 8th Jul 2019, 12:39 am   #4
matspar
Pentode
 
matspar's Avatar
 
Join Date: Aug 2009
Location: Portsmouth, Hampshire, UK.
Posts: 230
Default Re: Philips 492U aerial connectivity

That's a great help very many thanks Gents! I will probably go for one of the Ebay ones just for the ease of fitment. Pieter here are a few pics to give you an idea. How rare is the 492U? I can't seem to find another example online.
Attached Thumbnails
Click image for larger version

Name:	20190513_115051.jpg
Views:	206
Size:	62.3 KB
ID:	186338   Click image for larger version

Name:	20190614_163940.jpg
Views:	164
Size:	53.6 KB
ID:	186339   Click image for larger version

Name:	20190614_140556 (2).jpg
Views:	159
Size:	70.8 KB
ID:	186340   Click image for larger version

Name:	20190614_141417.jpg
Views:	165
Size:	57.2 KB
ID:	186341   Click image for larger version

Name:	9.jpg
Views:	186
Size:	62.3 KB
ID:	186342  

matspar is offline  
Old 19th Jul 2019, 9:01 pm   #5
Pieter H
Tetrode
 
Join Date: Sep 2017
Location: Waalre, Netherlands
Posts: 67
Default Re: Philips 492U aerial connectivity

Hi Matt,
thanks a lot for the pictures!
A very nicely restored set you have. I suppose the last two pictures are before and after restoration? Was the MW31-74 sticker on the picture tube original? It's a picture tube code I've never seen. The standard tube for the 492U was the MW31-14C, later the MW31-17 and -18. So in any case this looks like a replacement tube.

As to the uniqueness of your set: I think it is very rare. Although I'm always surprised to see how old sets turn up unexpectedly, I haven't seen any so far and I'm not aware of the existence of others. All I have are pictures from old Philips advertisements, so yours are the first of a real set. I might use one of them on my site if you don't mind.

Regards, Pieter
Pieter H is offline  
Old 20th Jul 2019, 5:26 pm   #6
FERNSEH
Dekatron
 
FERNSEH's Avatar
 
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
Default Re: Philips 492U aerial connectivity

The 441 line Philips TF402A is very similar in appearance to the model 492U.

https://radio-piffret.pagesperso-orange.fr/TV.htm

https://radio-piffret.pagesperso-ora...402A29_doc.jpg

The TF402A has a mains transformer and the HT rectifier is an AX50.

DFWB.
FERNSEH is offline  
Old 22nd Jul 2019, 3:15 pm   #7
Maarten
Dekatron
 
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,185
Default Re: Philips 492U aerial connectivity

Very nice to see more of those old sets!

To possibly determine the history of the MW31-74 in this set, could you have a look at the factory code? It's 2 lines of a few characters just as on normal valves, but it can be located either on the socket or stamped on the cone. It should contain a date code.
Maarten is offline  
Old 22nd Jul 2019, 3:29 pm   #8
Jac
Heptode
 
Jac's Avatar
 
Join Date: Jun 2006
Location: Eindhoven, Netherlands.
Posts: 640
Default Re: Philips 492U aerial connectivity

Click image for larger version

Name:	D62 1995-05-30.jpg
Views:	128
Size:	37.1 KB
ID:	187169

Jac
Jac is offline  
Old 26th Jul 2019, 11:11 am   #9
SteveCG
Nonode
 
Join Date: Jun 2009
Location: Herefordshire, UK.
Posts: 2,495
Default Re: Philips 492U aerial connectivity

I wonder what balanced input aerial impedance Philips designed the set for?
300 Ohm was a USA standard, but I believe the Germans and others used 240 Ohm and some UK set makers used 75 Ohm. Finally, 75 Ohm unbalanced was adopted in the UK and with the widespread use of Cable TV, 75 Ohm unbalanced became the norm elsewhere.
SteveCG is offline  
Old 31st Jul 2019, 1:23 am   #10
matspar
Pentode
 
matspar's Avatar
 
Join Date: Aug 2009
Location: Portsmouth, Hampshire, UK.
Posts: 230
Default Re: Philips 492U aerial connectivity

Thanks everyone for your interest and replies. I fitted the MW31-74 as the original MW31-14c had an o/c heater due to a past heater chain bodge.
I have since rebuilt the chassis and the reciever is now producing pictures and performing very well. It required a lot of work, apart from the replacement crt I replaced all of the pitch covered capacitors and most of the electrolytics which were all suffering from severe leakage. Many were also dead short.
Very interested to learn about the rarity of this set. Could this be the only one of its type left in existence I wonder? internally it is dated Nov 1949. Here are some photos of the finished chassis. I am currently restoring the cabinet which needs some refinishing mainly to the curved front surround. The rest should repolish quite well and retain the original finish.
Attached Thumbnails
Click image for larger version

Name:	20190721_204727.jpg
Views:	99
Size:	53.0 KB
ID:	187603   Click image for larger version

Name:	20190721_210914.jpg
Views:	96
Size:	45.4 KB
ID:	187604   Click image for larger version

Name:	20190724_201614.jpg
Views:	93
Size:	50.2 KB
ID:	187605   Click image for larger version

Name:	66398854_10162133890960220_8345425492567916544_n.jpg
Views:	92
Size:	92.8 KB
ID:	187606   Click image for larger version

Name:	20190730_203205.jpg
Views:	89
Size:	84.0 KB
ID:	187607  

matspar is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 2:00 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.