UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio 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 23rd Jul 2016, 10:01 am   #101
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 5,782
Default Re: Earliest BBC2 Sets?

Re posts 94, 98 and 100.
I don't think the set in post 94 is the 11u chassis, it looks more like the Pye67/Ekco 510 series with integrated transistor Tuner/IF or the next model with seperate Tuner/IF.
see https://www.vintage-radio.net/forum/...ad.php?t=58355

Frank
Nuvistor is offline  
Old 23rd Jul 2016, 12:42 pm   #102
Mad Mal
Tetrode
 
Join Date: Jul 2016
Location: Spennymoor, County Durham, UK.
Posts: 69
Default Re: Earliest BBC2 Sets?

Quote:
Originally Posted by MALC SCOTT View Post
Rediffusion did the same trick with the MK10 aerial sets. Poor performance but looked very nice!
Do you remember those horrible single board Mk 11 wired sets. I picked one out from the pile of sets on the floor thinking this will be easy."Smoother shot". The can had literally exploded its innards all over the inside of the set. The electrolyte had all but eroded most of the print tracks . As luck had it Dave was scrapping one off and I replaced the board. But, dave (Leithbridge) had me spend nearly an hour cleaning the inside of the cabinet. Replaced the smoother and... It worked. However there was a line tearing fault. Sorted it eventually but wasted a lot of time on one set.
Mad Mal is offline  
Old 23rd Jul 2016, 12:51 pm   #103
Mad Mal
Tetrode
 
Join Date: Jul 2016
Location: Spennymoor, County Durham, UK.
Posts: 69
Default Re: Earliest BBC2 Sets?

Quote:
Originally Posted by peter_scott View Post
Valve UHF tuners were pretty awful. Low gain and noisey.
Quite why we in Britain and Europe insisted on standard sizes valves (occasionally the miniature types) I cannot understand. RCA in the states used NuVistors in their VHF and UHF tuners. These ultra miniature, metal encased beauties performed exceptionally well. Why this idea was so short lived is a shame. I have a circuit and building instructions somewhere for making a 2M transceiver using two RCA Nuvistors in the RF and a third in the Audio stages.
Mad Mal is offline  
Old 23rd Jul 2016, 1:55 pm   #104
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 5,782
Default Re: Earliest BBC2 Sets?

Quote:
Originally Posted by Mad Mal View Post
Quite why we in Britain and Europe insisted on standard sizes valves (occasionally the miniature types) I cannot understand. RCA in the states used NuVistors in their VHF and UHF tuners.
Hi Mal,
Have you any information on Nuvistors being used in UHF tuners in the States. I have seen circuits for VHF tuners using Nuvistors but could never find any UHF ones. Most UHF tuners I can find are tuned input, crystal mixer and valve osc. The varactor tuned transistor UHF tuners seemed to use a RF stage similar to European transistor tuners.

Knowing how the first UK valve UHF tuners were noisy, I wonder how the reception in the States was on UHF with those valve/diode mixer tuners. The States had some system, I understand, that attempted to keep station coverage similar by allowing different ERP on bands,1, 3 and UHF with upto 5MW for some UHF stations, whether any used that power I don't know.

It has been mentioned before on the forum that Philips seemed to get the best out of their PC88/PC86 valve tuners, they produced better results than many others.

Attached is the performance of a high end RCA tuner for their colour sets circa 1955, the noise figure is quite high, I understand a good PC88 type tuner is around 8db but would really like confirmation if anyone can verify.

Frank
Attached Thumbnails
Click image for larger version

Name:	image.jpg
Views:	66
Size:	37.4 KB
ID:	127754  

Last edited by Nuvistor; 23rd Jul 2016 at 2:08 pm.
Nuvistor is offline  
Old 23rd Jul 2016, 2:10 pm   #105
julie_m
Dekatron
 
Join Date: May 2008
Location: Derby, UK.
Posts: 6,764
Default Re: Earliest BBC2 Sets?

Nuvistors were short-lived because transistors were soon able to do their jobs, better.

I'd guess that European valve manufacturers -- who, remember, were also semiconductor manufacturers -- could see the writing on the wall: the new wonder material, silicon, was going to displace the thermionic valve from its throne any day soon now, so didn't want to introduce another blind-alley technology that might become obsolete even before the tooling was paid for, especially not if it would have required licensing foreign Intellectual Property. (We'd already been burned before, with exotic improved exhaust systems for steam engines that increased efficiency and reduced coal consumption -- just not by enought to outweigh the cost of the royalties.) Hence we ended up with stumpy little seven- and nine-pin valves, with extra anode and grid pins to minimise stray inductance (just like resistors, the inverses of inductances in parallel add up). And so the R&D boffins just had to jolly well work harder on inventing transistors with gain at UHF; because they, too, wanted decent pictures on their TV sets.
__________________
Julie {formerly known AJS_Derby}
julie_m is offline  
Old 23rd Jul 2016, 2:17 pm   #106
Nicklyons2
Octode
 
Nicklyons2's Avatar
 
Join Date: Jan 2013
Location: Barnsley, South Yorkshire, UK.
Posts: 1,515
Default Re: Earliest BBC2 Sets?

Quote:
Originally Posted by Heatercathodeshort View Post
Quote:
Originally Posted by Nicklyons2 View Post
The earliest specimen I saw, at the time, was the Murphy V659. A lovely looking thing with a VHF tuner which resembled a pre-sliced pie. The big BUT is it was a 'convertible to' set and I never saw one which had been converted... has anyone?
They worked very well And must have been the easiest conversion of all time. It was simply a matter of turning the receiver on end,removing the locking screw on the 405/625 system switch, screwing the 'plinth' to the underside of the cabinet, inserting the octal plug from the unit to the socket mounted on the bottom of the chassis after removing the blanking plate and the job was done. The conversion unit worked very well containing a UHF tuner and complete IF strip.
One rather quaint oddity was that you had to wait for the valves to warm up in the converter when 625 was selected and again when returning to 405. I would like to obtain a 'plinth' converter. I have an excellent example of the V759 and it would be nice to find a conversion unit. I have no doubt one will turn up when least expected.
Very few of this series survived. The Early Mazda CME1901 and the 23" CME2301 tubes were a disaster failing just out of guarantee. Add to this a delicate and expensive oil filled line output transformer that could only be obtained from your local Murphy dealer and you had a receiver that was too expensive to overhaul for resale. Many were reluctantly scrapped prematurely. They also had design faults requiring tiresome modifications but once sorted out were quite outstanding performers. Murphy Radio's last chassis before the Rank take over including a motor driven remote control model with dual channel relay amplifiers and tuning forks for channel change and muting! Don't ask but it worked very well. Regards, John.
I'm indebted to John for the extra info on these sets I didn't have many to look after but I thought they were handsome sets. The CME1901 was a bit of an oddity in itself claiming 114deg deflection rather than the 110deg norm; the expected advantage of a slimmer set being negated by the fact it had a long neck and was actually around 15mm longer than the more common AW47/91 (which is what I used to replace them with). What I didn't know existed, never even seen a photo, was a 23" version how marvelous that must have looked particularly so with the convertor attached.

The last I knew 'in service' made it up to the end of System A, it was the spare set in the front room for when the family couldn't agree what to watch on the main set.
Nicklyons2 is offline  
Old 23rd Jul 2016, 2:17 pm   #107
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 5,782
Default Re: Earliest BBC2 Sets?

According to this article, reprint from PT Dec 1962, there were Mullard Nuvistors. The article says Mullard developed them, so I presume they did.
http://www.thevalvepage.com/valvetek...r/nuvistor.htm
Frank

Last edited by Nuvistor; 23rd Jul 2016 at 2:21 pm. Reason: it helps to include the web link
Nuvistor is offline  
Old 23rd Jul 2016, 2:42 pm   #108
julie_m
Dekatron
 
Join Date: May 2008
Location: Derby, UK.
Posts: 6,764
Default Re: Earliest BBC2 Sets?

I think you missed the link, but I managed to find this with a moment's searching. Now, I hadn't seen that article before, and presumed Nuvistors to be purely American. Still, Mullard were certainly in a position to afford a little each-way bet on that horse, even if smaller valve manufacturers didn't dare.

At any rate, the 6V3 / 135 mA heaters would have rendered the Mullard Nuvistors unsuitable for use in British TVs of the day. So were they after the Continental TV market, or laboratory instruments?
__________________
Julie {formerly known AJS_Derby}
julie_m is offline  
Old 23rd Jul 2016, 3:12 pm   #109
SteveCG
Octode
 
Join Date: Jun 2009
Location: Herefordshire, UK.
Posts: 1,870
Default Re: Earliest BBC2 Sets?

Apart from a dual-standard KB (VC1/2 chassis ?) which I came across in later years I've never used a valve tunered set in anger (And that was only in easy Group A, 1 MW, Sandy Heath, flat landscape territory). However I did come across the Philips Tvette - the dual-standard transistor portable TV - as a friend had one for use in a caravan. This was in the BBC2-only UHF days. To me, a casual observer then, it seemed to perform well on UHF. Perhaps others here did a better comparison with proper mains sets?
SteveCG is offline  
Old 23rd Jul 2016, 3:21 pm   #110
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 6,161
Default Re: Earliest BBC2 Sets?

Amusingly, in the very early-1960s RCA-Victor sold an entire series of consumer electronics - monochrome/colour TVs, radios, stereo-systems - badged as the "New Vista" range.

Though most of these didn't include Nuvistors in their component-count, I guess it was an easy way to make the association in peoples' minds - just as there were plenty of car radios of the era whose front panel said "TRANSISTORIZED" when the reality was the only transistors were a couple in the HT power-supply inverter (or maybe one as a class-A output stage in conjunction with 12-volt-HT valves).
G6Tanuki is offline  
Old 23rd Jul 2016, 4:08 pm   #111
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 5,782
Default Re: Earliest BBC2 Sets?

The book "Window to the Future" by Steve Kosareff includes an advert for the "RCA Mark 8 Color TV" using the New Vista chassis.
Quote. " equipped with RCA Victor's famed New Vista tuner you get unsurpassed picture-pulling power even in many difficult TV signal areas"
Unfortunately the book does not date the adverts but I presume 1960-62.

Frank
Nuvistor is offline  
Old 23rd Jul 2016, 4:30 pm   #112
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 6,161
Default Re: Earliest BBC2 Sets?

Just out of interest - were any UK TVs ever equipped with Nuvistor front-ends?

I rather suspect not - by the time UHF TV became anything more than a curiosity here the world had moved on to transistors and was focussing on the likes of the AF139/239 and Texas Instruments' GM0290.

(One place I'd have expected to see Nuvistors used was VHF/UHF mobile-radio transceivers - but none of the Pye/Storno/Ericsson/Siemens/Marconi/Philips/GEC stuff I ever worked on used them)
G6Tanuki is offline  
Old 23rd Jul 2016, 5:09 pm   #113
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 5,782
Default Re: Earliest BBC2 Sets?

None used in the UK that I know of, the trend was to replace the cascade RF amp with a neutralised triode such as the PC97 (1961) and PC900 (1963).
I first saw these in Thorn TV's in the VHF tuners, others makers followed later. How well these worked compared to the frame grid PCC89/189 valves I don't know, we were in a good signal area.
I would not be surprised if the change was to reduce costs, but it would be nice to know if they were a technical improvement.
Frank
Nuvistor is offline  
Old 23rd Jul 2016, 5:15 pm   #114
FERNSEH
Dekatron
 
FERNSEH's Avatar
 
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 5,176
Default Re: Earliest BBC2 Sets?

Interesting you should mention that. in the early 1960s Mullard did in fact make Nuvistor valves but possibly because the these valves do not have a 0.3amp heater UK TV tuner manufactures did not employ them, adopting the PC95, PC97 and PC900 RF triodes instead.

DFWB.
FERNSEH is online now  
Old 23rd Jul 2016, 7:32 pm   #115
slidertogrid
Heptode
 
Join Date: Apr 2005
Location: Peterborough, Cambridgeshire, UK.
Posts: 804
Default Re: Earliest BBC2 Sets?

Quote:
Originally Posted by Nuvistor View Post
Re posts 94, 98 and 100.
I don't think the set in post 94 is the 11u chassis, it looks more like the Pye67/Ekco 510 series with integrated transistor Tuner/IF or the next model with seperate Tuner/IF.
It is indeed a 368 chassis, that's what's in the Invicta set I have, same as the Pye Olympic apart from cabinet and knobs.
The Ekco in my post is the 11U chassis.
Rich.
slidertogrid is offline  
Old 23rd Jul 2016, 7:58 pm   #116
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 5,782
Default Re: Earliest BBC2 Sets?

Oops, my misunderstanding.
Frank
Nuvistor is offline  
Old 23rd Jul 2016, 8:46 pm   #117
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 6,255
Default Re: Earliest BBC2 Sets?

The first 19 and 23" CRT's employed in the early convertible receivers were of the long neck design. As mentioned, Mazda's offerings were the CME1901 and CME2301. The nearest Mullard equivalents of these were the AW47-90 and AW59-90. As Nick has said these could be replaced with the shorter neck Mullard and Mazda types that were supplied from 1962.The heater voltages differed but this was not a problem in a series heater chain.
Mazda produced the best screens and gave superb pictures but had unexplainable problems with the gun assemblies. The CME1901 used to develop an O/C cathode. A very dim focused raster with a very weak uncontrollable picture could be seen with the room lights out. Giving the neck a clout would return the picture but just for a few seconds. This was a very frustrating fault that upset customers who were brave enough to purchase these early convertibles. The Mazda tube was also used in the 'convertible' [if you could call it that] Ultra 1984C, the last model they produced before the Thorn take over, and like Ekco had the same tube problems. The later Mazda 'Gold Star' types were no better.
Not such a good time for the poor manufacturers but they sure kept the service engineers busy. Regards, John
Heatercathodeshort is offline  
Old 23rd Jul 2016, 9:09 pm   #118
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 5,782
Default Re: Earliest BBC2 Sets?

The Mazda CRT's with O/C cathode, oh yes, remember them well. Has you say John the pictures were excellent, just did not last. Usually replaced with a Mullard or Cathodeon CRT, and those usually lasted the life of the set.

Frank
Nuvistor is offline  
Old 23rd Jul 2016, 9:38 pm   #119
FERNSEH
Dekatron
 
FERNSEH's Avatar
 
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 5,176
Default Re: Earliest BBC2 Sets?

The Mazda CME1901 was unusual in having a 114 degree deflection angle.
Another 114 degree CRT was the Brimar C19AH, this was a really slim tube as it had a very short gun assembly. The C19AH was fitted in the very rare KB UV30 625 convertible receiver.
https://www.vintage-radio.net/forum/...d.php?t=108023

DFWB.
FERNSEH is online now  
Old 24th Jul 2016, 1:46 pm   #120
dazzlevision
Octode
 
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 1,959
Default Re: Earliest BBC2 Sets?

Quote:
Originally Posted by Heatercathodeshort View Post
(Re. the Murphy Astra series TV chassis)
They also had design faults requiring tiresome modifications but once sorted out were quite outstanding performers. Regards, John.
Hello John,

I would be interested to learn more about the mods required to overcome design faults in the Astra TV chassis.

I know there were mods to the ultrasonic remote control system in the relevant models; the plug-in flywheel sync PCB (to overcome video information folder on the LHS, on 625 working); to overcome 405-625 switching delay in converted sets (due to not all heaters being powered up on both line standards) and to enable VHF/625 line working.

I am not aware of any other major mods to the basic chassis......?

Regards,

Dazzle vision
dazzlevision is online now  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 11:08 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 - 2018, vBulletin Solutions, Inc.
Copyright ©2002 - 2018, Paul Stenning.