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THE GREAT MULLARD MAGIC BLOG

DO VALVES WEAR OUT (i)? - EMISSION LOSS

Posted by STEVE M on

DO VALVES WEAR OUT (i)? - EMISSION LOSS

If a valve passes an anode current of 1mA then this equates to 650, 000, 000, 000, 000 electrons a second.  When you consider that an output tetrode like a KT66 can pass up to 100mA in anode current then as Cilla Black would have said 'that's a lorra, lorra electrons!'    I think this little fact demonstrates quite well that over a period of anywhere between 2000 and 8000 hours on average, a valve may loose a proportion of it's emissive properties.  During the early life of a valve, the effect of emission loss is realtively imperceptible but after...

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TUBES BOLDLY GO WHERE NO TUBE HAS GONE BEFORE

Posted by STEVE M on

TUBES BOLDLY GO WHERE NO TUBE HAS GONE BEFORE

Well, here we are again with part two of this scintillating blog, and I thought I had better change the title as we are talking about an American sci-fi series so our teminology needs to reference tubes instead of valves - that's right innit? Anyhow, we were discussing the 1964 pilot episode of Star Trek TOS, The Cage and the valves therein..... so... where were they then ...... well, they were in the communicator. And as proof, here we see Mrs Roddenberry, complete with futuristic 23rd century blue nail varnish wielding her communicator whilst standing next to Captain Pike.  ...

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VALVES BOLDLY GO WHERE NO VALVES HAVE GONE BEFORE...............

Posted by STEVE M on

VALVES BOLDLY GO WHERE NO VALVES HAVE GONE BEFORE...............

Well, we have all heard the stories of good old valve powered Collins R390A being used in Operation Desert Storm but whoever would have thought that valves would still be used in frontline space exploration in the 23rd century???     No, I am not a time traveller, just a keen fan of Star Trek and although I prefer TNG, I have a lasting appreciation of TOS too and so, let’s go back to the very start with the pilot episode, The Cage. "The Cage" , set in the year 2254, was completed in early 1965 by Gene Roddenberry but not broadcast on...

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CAN YOU TELL ME ABOUT MULLARD TROPICAL FISH CAPACITORS?

Posted by STEVE M on

CAN YOU TELL ME ABOUT MULLARD TROPICAL FISH CAPACITORS?

Again, I shall pause from my historical Mullard meanderings to answer a query I have received from a customer from Malaysia about the Mullard ‘Tropical Fish’ capacitors, so called due to their colourful body stripes which denote value – more on this later! These capacitors, introduced to the radio market in 1964 have a polyester dielectric which exhibits very low dielectric loss, high insulation resistance coupled with good temperature and moisture resistance, however, for physical integrity they are not perhaps as tough as the Mullard ‘Mustard’ capacitors.   All told though, they far exceed the efficiency of paper dielectric capacitors and...

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WOMEN - AN IMPORTANT MARKET FOR THERMIONIC DEVICES IN THE 1950S

Posted by STEVE M on

WOMEN - AN IMPORTANT MARKET FOR THERMIONIC DEVICES IN THE 1950S

Ah nostalgia, it's a great thing isn't it when we all look back with rose tinted spectacles to a golden age (how many metaphors can we get in this sentence?) when things were better.  A time when the mention of "boy jobs" and "girl jobs" didn't meet with the hysterical chuffing from a legion of permanently aggrieved and offended snowflakes, taking to their phones in an outpouring of their displeasure in hashtags, emojis and other associated drivel on Twitter;  happy days, happy days indeed. Anyhow, I thought we would have a quick look back to the fabulous fifties and study how...

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