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 Radio (domestic)

Notices

Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

Reply
 
Thread Tools
Old 1st Feb 2019, 4:53 pm   #21
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 49
Default Re: Ultra Model 50 (1937) Restoration

Also check the rear earth socket which is "riveted" to the chassis. Mine is showing a very bad electrical connection to the chassis and it is used to earth a few components. I'll be running a lead from a soldered tag on the chassis to this socket.
DoubleWound is offline   Reply With Quote
Old 4th Feb 2019, 9:30 pm   #22
OldTechFan96
Heptode
 
OldTechFan96's Avatar
 
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 766
Default Re: Ultra Model 50 (1937) Restoration

I have been doing some more checks on the Ultra.

All of the valves have have been checked for heater continuity. All heater voltages are correct at 4VAC.

Paper capacitors have been checked and are all leaky on the 20v-100v setting. C17 was O/C and was replaced. Most of have drifted but are not too bad.

First switch on:

Using lamp limiter the smoothed HT reached 140v. The bulb settled to be semi-bright, those leaky capacitors won't help. Tunable signals (using a 10M long wire antenna) could be heard on MW and LW. Maybe SW too. Only strong stations could be heard. Audio quality was poor and quiet at higher volumes. V1 and V3 did not seem to get warm. Too low HT may explain this.

I did not want to turn off the limiter because of how leaky the capacitors are!

My next step will be to replace the paper capacitors.

I'll check the earth socket for any loose rivets.
OldTechFan96 is offline   Reply With Quote
Old 9th Feb 2019, 8:39 am   #23
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 49
Default Re: Ultra Model 50 (1937) Restoration

We both make progress.

I have rewound the aerial coil and it ended up at 10 Ohms instead of the specified 15 Ohms but I believe it should be OK.

The non original output transformer was found to have an extremely high primary resistance and I have sourced a second hand transformer with a primary of 400 Ohms although the specified resistance is 325 Ohms. Once again, I think that should be OK.

14 new capacitors have been delivered and when fitted along with the replacement output transformer I'll turn the set on and measure voltages.
DoubleWound is offline   Reply With Quote
Old 9th Feb 2019, 10:44 am   #24
OldTechFan96
Heptode
 
OldTechFan96's Avatar
 
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 766
Default Re: Ultra Model 50 (1937) Restoration

The order of capacitors came on Wednesday. I'm not too sure when I'll have time to fit them.

I have worked on a handful of valve radios before. These were usually from the late 1950's. I'm wondering what the neatest method would be for fitting replacement capacitors? Especially hiding the join between a capacitor leg and the wire that it attaches to.

Nice one on the coil rewind, DoubleWound! Did you use a coil rewinder?
OldTechFan96 is offline   Reply With Quote
Old 9th Feb 2019, 11:06 am   #25
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 49
Default Re: Ultra Model 50 (1937) Restoration

I will try to use heat shrink sleeving to cover soldered joints between wires and components. Time will tell if I find the enthusiasm to perform this on original joints that will not be disturbed in the capacitor replacement exercise. The method of wiring was certainly messy in 1937!!

The aerial coil was wound by hand between two cardboard cheeks. I've left the cheeks there as I cannot see how they would affect coupling to the LW and MW coils. I hope the number of turns (125) was correct because it was difficult to count the original number whilst unravelling the burnt out coil. It was difficult to solder the new wire and especially the original LW wires which had to be disconnected for access. However, correct continuity has been restored. It may be fun checking the alignment but that is a long way away.

The mains on/off switch on the volume pot is also not working so I'll be looking for a replacement unless switch cleaner works.
DoubleWound is offline   Reply With Quote
Old 16th Mar 2019, 9:13 pm   #26
OldTechFan96
Heptode
 
OldTechFan96's Avatar
 
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 766
Default Re: Ultra Model 50 (1937) Restoration

I'm back on the case of the Model 50. All bar two of the paper capacitors have been changed. My Rawlplug 100W soldering iron died last month due to some kind of earthing fault which caused 64VAC to be present on its tip. It came in contact with my Antex iron and there was a big spark. I need more heat to replace the last two capacitors.

The smoothing capacitors will be changed when I think of a neat way of hiding them under the chassis.
OldTechFan96 is offline   Reply With Quote
Old 17th Mar 2019, 3:11 pm   #27
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 49
Default Re: Ultra Model 50 (1937) Restoration

I'm pleased you've got going again and like you my 100W iron was needed for much of the soldering.

I've finished now and all the paper and electrolytic capacitors had to be replaced - I tested each old one after removal and they were all totally useless.

Also, I had to source a secondhand output transformer as the primary was virtually open circuit.

RF and IF alignment was way out and everything came in to line easily with an excellent text book IF curve.

Audio is very good and reception is fine on strong stations with a short indoor wire aerial.

I did refinish the case and had no choice but to replace the speaker fabric, the original being stained beyond hope.

Keep us posted with your set and I hope it goes well.
Attached Thumbnails
Click image for larger version

Name:	Ultra RH View.jpg
Views:	167
Size:	70.1 KB
ID:	180082  
DoubleWound is offline   Reply With Quote
Old 18th Mar 2019, 7:20 pm   #28
OldTechFan96
Heptode
 
OldTechFan96's Avatar
 
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 766
Default Re: Ultra Model 50 (1937) Restoration

Wow! What an excellent job on the that cabinet, DW! How did you do it? Could you please post some more photographs? The veneer does look quite striking!

The speaker cloth on mine does look dirty and I don't think it would survive any cleaning attempts.

The rubber tuning capacitor mounts will need replacing so I'll see what I can find.

You mention an IF curve. Do you have a wobbulator?
OldTechFan96 is offline   Reply With Quote
Old 19th Mar 2019, 3:25 pm   #29
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 49
Default Re: Ultra Model 50 (1937) Restoration

Thanks for those comments and I attach a pic from the other side. It's just hard work really - take all the woodwork apart rub down very carefully and hand brush with acrylic lacquer with an expensive Purdy brush.

Click image for larger version

Name:	Ultra LH View.jpg
Views:	114
Size:	93.7 KB
ID:	180186

My tuning capacitor rubber bushes were tired but additional spacers firmed the gang up nicely keeping enough resilience.

I have a Siglent Function Generator which is a joy to use. It's so easy to get spot on centre IF frequency and observe any peculiarities. It needs plenty of attenuation for RF and IF circuitry which is easy and cheap to achieve.

Click image for larger version

Name:	IF Trace.jpg
Views:	94
Size:	66.1 KB
ID:	180187

Click image for larger version

Name:	Mid Frequency 456kHz.jpg
Views:	81
Size:	65.2 KB
ID:	180188

The above pics were taken before alignment for the purposes of seeking advice from a knowledgeable friend. Mid frequency was seen to be at 446kHz, way out from the specified 456KHz. Regretfully I didn't take pics of the final perfect alignment. I injected into grid V2 - not the aerial socket as specified in the service sheet.

Keep us posted with your progress.
DoubleWound is offline   Reply With Quote
Old 15th Jul 2019, 8:04 pm   #30
OldTechFan96
Heptode
 
OldTechFan96's Avatar
 
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 766
Default Re: Ultra Model 50 (1937) Restoration

An update on the Ultra 50:

I recapped the radio in March/April and the radio fired right up. Stations were heard on each waveband with a 13m longwire aerial. LW might have been a bit spotty.

The anode voltages are all around what they should be apart from the V2 osc. anode.

The screen voltages of V1 and V2 need looking at.

Voltages for V2 screen and V2 osc. anode will probably be reigned in by replacing R8 and R12 as they are both reading high.

The V1 screen voltage is high and I don't think changing out R2 will sort things out. Maybe the valve is slightly weak?
Attached Thumbnails
Click image for larger version

Name:	IMG_E2222.jpg
Views:	42
Size:	29.9 KB
ID:	186760  
OldTechFan96 is offline   Reply With Quote
Old 16th Jul 2019, 7:18 am   #31
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 49
Default Re: Ultra Model 50 (1937) Restoration

It's coming along nicely OTF.

Attached are the voltages I measured, albeit with a non standard mains transformer and a U12 rectifier valve. I seem to remember changing some resistors with no effect on anything.

I found that the IF and RF alignments were quite easy to get correct compared with some 50s sets that I've worked on.

Keep us posted.
Attached Files
File Type: pdf Ultra 50 Various Voltages.pdf (328.1 KB, 38 views)
DoubleWound is offline   Reply With Quote
Old 11th Nov 2019, 8:34 pm   #32
OldTechFan96
Heptode
 
OldTechFan96's Avatar
 
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 766
Default Re: Ultra Model 50 (1937) Restoration

Recently I replaced the resistors mentioned in post #30. Changing R12 brought the V2 anode voltage up to 82V. Changing R2 and R8 did not have any effect.

The V1 and V2 screen voltages that I have recorded are higher than what is shown in the service manual; they are inline with what was recorded by DW in post #31.

The electrical aspect of this restoration is for the most part done. I would like to realign it once I get better equipment.

Next, I will try and replace the 4 rubber grommets that support the tuning capacitor. I think a lot of trial and error will be needed.

The cabinet has responded well to my T-cut and wax treatment. It looks good despite some of the lacquer flaking off.

Does anybody have any tips regarding the measurement of anode and screen current for this radio? I've only done this a few times before on another radio.
OldTechFan96 is offline   Reply With Quote
Old 15th Nov 2019, 3:55 pm   #33
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 49
Default Re: Ultra Model 50 (1937) Restoration

I'm glad it's all coming together OTF.

In addition to the tuning capacitor grommets, I also found a lot of trial and error was needed for the chassis grommets which on my set had become compressed.

I confess to have not checked anode and screen currents. I suppose the surefire way is to break the circuit and insert a multimeter. Perhaps measuring volt drop across some known value resistors is another method for some of the valves but you may have to break the circuit to measure resistance values anyway.

Keep us posted because it's a fine old set and I regret selling mine.
DoubleWound is offline   Reply With Quote
Old 13th Jan 2021, 11:58 am   #34
Cobaltblue
Moderator
 
Cobaltblue's Avatar
 
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 4,955
Default Re: Ultra Model 50 (1937) Restoration

Thread reopened at OldTechFan96's request.

Cheers

Mike T
__________________
Don't care if it was a bargain why's it in my kitchen
Mike T BVWS member.
www.cossor.co.uk
Cobaltblue is online now   Reply With Quote
Old 13th Jan 2021, 2:25 pm   #35
OldTechFan96
Heptode
 
OldTechFan96's Avatar
 
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 766
Default Re: Ultra Model 50 (1937) Restoration

Thanks to member Neutrino, I was able to get some grommets to properly remount the tuning capacitor. To get the required height I stacked two grommets on top of each other.

A new mains lead has been fitted and the chassis has been earthed. The dial glass has been refitted and two new dial bulbs have been installed.

The chassis mounts onto four large rubber grommets, which have all compressed a bit. I intend to shim them up with some 1mm square belts.

The cabinet has been rubbed down with some dark wood dye to hide small amounts of flaky lacquer. Some brown wax scratch remover was also rubbed into the cabinet and it is looking quite good.

Soon I'll get the cabinet back into the chassis.
Attached Thumbnails
Click image for larger version

Name:	IMG_3493.jpg
Views:	68
Size:	79.9 KB
ID:	224525  
OldTechFan96 is offline   Reply With Quote
Old 14th Jan 2021, 7:35 am   #36
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 49
Default Re: Ultra Model 50 (1937) Restoration

It's good to see that the project approaches completion. I'm hoping you've got a signal generator to perform alignment as my set was miles out, both RF and IF.
Looking forward to seeing the finished cabinet.
DoubleWound is offline   Reply With Quote
Old 18th Jan 2021, 2:38 pm   #37
OldTechFan96
Heptode
 
OldTechFan96's Avatar
 
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 766
Default Re: Ultra Model 50 (1937) Restoration

Thanks for your continued interest in the project DW and coming back after a year! I would like to perform a complete RF and IF alignment once I find better equipment. I have had my eye on the usual online sources for a few years but noting has been forthcoming.

I have been assessing the RF performance of the Model 50 with 10m long wire aerial against a Sokol 204.

On MW the 50 picks up all of the stations it should. There is an amount of background noise that ranges from slight to enough to make the station unlistenable. There is not this mush with the Sokol.

Radio 4 and RTE1 can be received but they are very poor.

SW will be looked at in the future.

I would like to think that the RF issues could be solved by realignment.

I bought some new mains lead before Christmas and fitted it. I then remembered that I wanted to use gold cloth covered lead that matched the original. Once postage was factored in 3m of cable was over 10 so I'll leave that for now.

There is still a few things I want to do:

Add spade terminals to the speaker wires to aid speaker removal.
Clean and straighten back. (done)
Add a period correct mains lead.
Straighten dial glass.
Asses audio performance and measure OP watts. (I made a cable to do this)
More chassis cleaning.

I would also like to do a neater job of the work under the chassis. It looks a bit rubbish and I would like to make it look better. I'm not sure how to approach this.

I would like to know how Ultra managed got away without a pre-amp valve? Is the demodulated signal sufficiently large that it can be passed straight to the OP valve?

I will try and post some photographs soon. My phone's camera is malfunctioning.

One more thing! I found three copper bolts amongst my '50' bits and pieces. Does anybody know where they are from? I don't think that they are from my other projects that I have on the boil.
Attached Thumbnails
Click image for larger version

Name:	IMG_3524.jpg
Views:	29
Size:	45.7 KB
ID:	224851  
OldTechFan96 is offline   Reply With Quote
Old 18th Jan 2021, 4:25 pm   #38
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 49
Default Re: Ultra Model 50 (1937) Restoration

Ref the lack of pre-amp, I've recently finished a GEC BC3740 of similar era and it gave plenty of volume without a pre-amp stage. I think the output valves used in this type of design had plenty of gain.

Have you checked the "rivetted" earth socket for continuity with the chassis? If you remember, mine was very bad and I added an earth lead.

Keep up the good work.
DoubleWound is offline   Reply With Quote
Old 19th Jan 2021, 8:03 pm   #39
OldTechFan96
Heptode
 
OldTechFan96's Avatar
 
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 766
Default Re: Ultra Model 50 (1937) Restoration

I'll check the earth rivet soon to see if it makes a good connection.

I would like to remove the IF cans to clean them properly. Do you know if this is tricky to do?

The chassis is cleaning up well. Removing the tuning capacitor again should not be much bother. I want to remove to the two smoothing cans but I don't have a suitable box spanner.
Attached Thumbnails
Click image for larger version

Name:	IMG_3552.jpg
Views:	29
Size:	75.9 KB
ID:	224964   Click image for larger version

Name:	IMG_3551.jpg
Views:	26
Size:	64.9 KB
ID:	224965  
OldTechFan96 is offline   Reply With Quote
Old 19th Jan 2021, 8:07 pm   #40
vinrads
Nonode
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 2,868
Default Re: Ultra Model 50 (1937) Restoration

It looks like two nuts under the chassis and two on top of the cans , the wire to the top cap will need to be unsoldered , Good luck with it , Mick.
vinrads is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 4:01 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 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.