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Radio and TV restoration.

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Radio and TV restoration.

Old 2nd Jun 2021, 02:24
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Radio and TV restoration.

I'm a member of such a forum. Takes me back, but not likely I'll ever become involved. However, I spotted this a few days ago. The bloke's had it for decades. EMI 5" Tube, and made just before the war . . . the same as me. Well, if you count the Phoney War as before, which is cheating I know. Anyway, I delved and was truly amazed.

My mom watched telly before the war. There was one in the pub down the road. Signals, and indeed the productions, must have been from Alexandria Palace. After the war we needed a tall mast in Walton on the Naze to get a rolling, line-fuzzing, sometimes-picture.

29 to 35 Gns. Given the supreme quality of the radio section, that was a bargain. If you see one of these in a boot-sale, buy it, if it's under a couple of grand. You'll need help lifting it.






http://worldphaco.com/uploads/HMV__904_ARTICLE.pdf
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Old 2nd Jun 2021, 05:15
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I've got a 1940s valve radio as my workshop boombox. Valves take a while to warm up but the sound quality is wonderfully rich. Weighs a ton. Will still work, so I'm told, after a Nuclear EMP warhead has fried all the transistor radios around. Hilversum, Luxembourg etc plastered over the dial.
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Old 2nd Jun 2021, 12:47
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Take a 'modern' piece of consumer or even professional equipment. It will have considerably more 'bells and whistles' - quite a few of which you probably will never use. Controlled by a microprocessor and with some other complex custom integrated circuits, and many ICs designed for consumer applications are designs which will come and go in as few as maybe as much as five years. Yes, reliability is higher, but 'repairability' if you haven't got the ICs can be practically zero. A company in South Africa some years ago had an order for some radar equipment repairs: the particular Plessey IC they needed had been out of production for 4 years (having had production life of 35 years!) and 2 year 'last time buy' notification. They found a company in Hong Kong who offered them 200 parts at $500 each. When they got them, the package marking was right, but the chips inside were definitely not. By the time they found this, the HK firm no longer existed, the bank account was closed, the money had been moved.....

It is actually easier to find parts to service a pre-war National HRO receiver than some modern radios....that includes the valves, too!

When Plessey closed their gold doped bipolar process down and gave MoD a last buy on Clansman parts, the ability to make them disappeared. MoD put all the parts in a warehouse at Donnington that caught fire....

The F35 aircraft has a lot of the CMOS made in Taiwan. I don't know if there are fabs in the US capable of that size wafers in sub micron processes.....
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Old 2nd Jun 2021, 14:33
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Was it NASA who put out a call for any spare 286 type computer CPU chips a while back, to keep the space shuttles going after the 286s went out of production. Or was that something else?

On a side-note, it blows my mind that they now get something like 39 billion transistors on a chip 31 mm x 31 mm - slightly bigger than an inch square. That's about 39 million transistors in a space 1 mm sq. How is that even possible?
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Old 2nd Jun 2021, 15:12
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One of the main sources of spare ICs for the Shuttle was eBay. NASA had a search engine with a list of devices with the required chips and bought anyth8ng which came up for sale second hand.
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Old 2nd Jun 2021, 16:10
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I recently supplied some parts to Cosworth, who wanted ones with drivers available for Windows 3.11. Apparently some of their test gear.....

In the 1980s I remember one of my guys complaining that I had sent him to fix a machine, one of which he had seen in the Science Museum the previous weekend.
It drove a rig for measuring turbine blades on RR engines. They reckoned it was cheaper to pay loads to keep the old one going than get a new one approved.
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Old 2nd Jun 2021, 16:10
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Originally Posted by radeng View Post
It is actually easier to find parts to service a pre-war National HRO receiver than some modern radios....that includes the valves, too!.
I remember well the HRO. When the Portland Spy Ring Trial took place the Telegraph published a picture obtained by one of their ace journalists, of a Top Secret Radio Transmitter used by the Krogers.
It was actually an HRO and I knew it wasn't Top Secret either because we had one at school !
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Old 2nd Jun 2021, 19:32
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We had National HRO receiver at the Admiralty Electronics Society at MoD Foxhill. I never did find out what happened to it when the site was closed down, although I have my suspicions!
Things were so much simpler back then, I'm currently exploring DMR and the intricacies of codeplugs. Deep joy!
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Old 2nd Jun 2021, 21:32
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I have a Bush DAC 90A. Bought it about 30 years ago and had it restored by one of the specialists companies full of 80 year olds wandering around in brown dust jackets.

Unfirtunately I haven’t used it much as it’s in a room facing the sea on Brighton sea front and picks up bugger all. Replaced it with an early, now vintage, FM radio.

It now sits forlorn on the bottom shelf of a bookcase. Not worth much (they sell for just over £100 before restoration). If anyone can offer it a good home - and possible second restoration - drop me a message.

Generic photo, not my radio.





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Old 2nd Jun 2021, 21:53
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Originally Posted by ORAC View Post
I have a Bush DAC 90A. Bought it about 30 years ago and had it restored by one of the specialists companies full of 80 year olds wandering around in brown dust jackets.

Unfirtunately I havenít used it much as itís in a room facing the sea on Brighton sea front and picks up bugger all. Replaced it with an early, now vintage, FM radio.

It now sits forlorn on the bottom shelf of a bookcase. Not worth much (they sell for just over £100 before restoration). If anyone can offer it a good home - and possible second restoration - drop me a message.

Generic photo, not my radio.


I've got one of these in white Bakelite. It's been used as a prop in AmDram productions, even with the sound effects actually coming out of the speaker but I've left the innards intact. I'll have to give it a going over on the workbench and see if it still works. Last time I used it (as a real receiver) was about 20 years ago.
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Old 2nd Jun 2021, 22:26
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[QUOTE=ORAC;11056076}they sell for just over £100 before restoration/QUOTE]

Obviously things are worth what someone will pay for them but most vintage radio restorers / enthusiasts would not pay more than about £25 - £50 for an unrestored DAC90a dependant upon condition. Prices being asked on eBay are often grossly over inflated and anyone "in the know" would generally buy from the vintage radio forums or at rallies where the prices will be much more realistic.

Here are a few of mine, all bought unrestored for less than £50 and now in full working order.




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Old 3rd Jun 2021, 00:03
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At one stage, the US Federal Aviation Administration was the worlds largest consumer of vacuum tube valves. They were forced to buy spares from former communist countries which still made them as the rest of the world had long since gone to transistors.

These days valves would mainly be found in high end HiFi equipment with Russian tubes regarded as the best. The heat coming off some of the larger set ups was very noticeable and the power consumption must have been reflected in the electric bill.

I saw a 1970s vintage, valve amp on sale in a second hand shop and it still worked. Being able to diagnose faults with basic test equipment and push in a new tube would keep it going indefinitely, compared to today’s equipment which becomes junk once limited production run parts are no longer available if needed.

Perhaps valves will be like vinyl records and refuse to die out.
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Old 3rd Jun 2021, 08:01
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Originally Posted by krismiler View Post
These days valves would mainly be found in high end HiFi equipment with Russian tubes regarded as the best.
The biggest user of valves these days is almost certainly guitar amplifiers, all of the major manufacturers (Fender, Marshall, Vox etc) still produce large quantities of these. There are currently only 3 factories in the world producing valves, JJ Electronics in the Slovak Republic, the Reflektor Company in Russia, and Shuagang in China. There are a multitude of different brand names available but all are re-branded items and will have been produced in one of these 3 factories. As for which are regarded as the best, yes, the Russian (and the Slovak) produced valves are generally considered to be better quality than Chinese produced ones, however the ultimate "must have" for some audiophiles (audiofools!) would be new old stock valves made back in the heyday of valve production, the prices that some will pay for valves made at the Mullard Blackburn factory are eye-watering!
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Old 3rd Jun 2021, 08:07
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I have a Bush AC34 which I have owned for 49 years - it always worked ok and sounded lovely,I have not actually switched it on for about 5 years as it is parked on top of our 6 feet high main living room cabinet (small house - no space LOL).This is a pic from the Snellings Museum - mine is in almost as nice condition considering it has never been restored but not easy to get a nice pic of it.

https://www.snellingsmuseum.co.uk/our-history

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Old 3rd Jun 2021, 08:17
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Remember one particular radio that caused me grief, and I refurbished many over the years.
Think it was an HMV set and the valve (tube) heaters received their dropped ac supply from the mains lead which incorporated the coiled resistance. Owner of the set hadnít realised you canít shorten the lead.
Never had a problem sourcing valves but usually they werenít the problem. Wavechange switches caused the most grief with sections scattered around the chassis deep in the bowels of the radio.
Still listen to my old Stella that has developed a mains hum recently.

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Old 3rd Jun 2021, 08:31
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The resistive mains cables were quite common on some AC/DC live chassis sets and often a source of problems. They were superseded on later sets by large dropper resistors inside the set and then later as DC mains became obsolete transformers were used to supply the correct voltage to the heaters. The most likely cause of your mains hum will be the filter capacitors in the HT power supply.
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Old 3rd Jun 2021, 11:19
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Originally Posted by Loose rivets View Post
I'm a member of such a forum. Takes me back, but not likely I'll ever become involved. However, I spotted this a few days ago. The bloke's had it for decades. EMI 5" Tube, and made just before the war . . . the same as me. Well, if you count the Phoney War as before, which is cheating I know. Anyway, I delved and was truly amazed.

My mom watched telly before the war. There was one in the pub down the road. Signals, and indeed the productions, must have been from Alexandria Palace. After the war we needed a tall mast in Walton on the Naze to get a rolling, line-fuzzing, sometimes-picture.

29 to 35 Gns. Given the supreme quality of the radio section, that was a bargain. If you see one of these in a boot-sale, buy it, if it's under a couple of grand. You'll need help lifting it.






http://worldphaco.com/uploads/HMV__904_ARTICLE.pdf
wonder if it's the same forum I joined yesterday. Trying to give away a Lafayette HE30. Weighs about as much as me.
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Old 3rd Jun 2021, 14:40
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Many years ago, during my RAAF Electrical training I was tasked with fixing a TV for the electronics phase ( TV Repair wasnt part of the course) . I repalced two valves, 6AL3 and 6V6G ( I used to subscribe to electronics Australia magazine, and i recalled that these valves were the usual culprits) and the TV worked. The Instructors were suitably impressed that I fixed it, and in ten minutes. I passed that course..
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Old 3rd Jun 2021, 16:24
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Originally Posted by Mr Optimistic View Post
wonder if it's the same forum I joined yesterday. Trying to give away a Lafayette HE30. Weighs about as much as me.
Ah yes, a Lafayette HE30. They looked so neat and functional. I used to drool over adverts for them in the 1960's.
Sadly I had to make do with my shortwave radio which came in a wooden crate from Hong Kong for about £20 ish. I still have the box, but not the set (5 valves I think).
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Old 3rd Jun 2021, 16:45
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Krismiler

At one stage, the US Federal Aviation Administration was the worlds largest consumer of vacuum tube valves. They were forced to buy spares from former communist countries which still made them as the rest of the world had long since gone to transistors.
At the time of the Falklands "unpleasantness" some 40 or so years ago, it was discovered that spare klystrons for some older RN navigational radars were only available from Poland....

At least relatively few thermionic valves went from introduction to obsolescence in around 5 years....

BTW, the last 35 years of my professional career was in the integrated circuit industry!
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