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...is the answer 42?Much less than a metre
...is the answer 42?Much less than a metre
are we talking about a front end, pi tank, 5/8ths whip etc or diameter?How much wire is there in a 2 metre coil ? ( hint.. trick question )
..is the answer 42?
Well, in the world I used to spend a lot of playing in, a "2 meter coil" would actually be a "144 MHz coil" (well, actually, a 144 Mc/s coil back then!) - or, more precisely, the coil of a 144 MHz tuned circuit .... and the 'coil' of a 144 MHz tuned circuit would be made of only a few inches of wire!How much wire is there in a 2 metre coil ? ( hint.. trick question )
I can't add a pic by editing my previous post - so, here a "2m coil" which ""I made (nearly 55 years!) earlier" - with a bit of paper for clarity, and a 20p piece for scale.Well, in the world I used to spend a lot of playing in, a "2 meter coil" would actually be a "144 MHz coil" (well, actually, a 144 Mc/s coil back then!) - or, more precisely, the coil of a 144 MHz tuned circuit .... and the 'coil' of a 144 MHz tuned circuit would be made of only a few inches of wire!
Blimey, that resonates with me . My old college lecturer taught us this bonkers ‘resonant frequency’ mnemonic: “Down in the jungle having a look see,..1 over 2pi root LC”I can't add a pic by editing my previous post - so, here a "2m coil" which ""I made (nearly 55 years!) earlier" - with a bit of paper for clarity, and a 20p piece for scale.
View attachment 163180
Kind Regards, John
You're welcome.Thanks John, I was looking unsucessfully for an image to explain the answer,
Indeed. It's nice/nostalgic to see a 1kΩ resistor which is big enough and with a light enough background to be able to read the 'rings' without struggling! The close-up photography, 50+ years on, does not say a lot for my soldering proficiency 'back then'!The good old days.......
In context, the problem with that mnemonic is that, in relation to the first pic I posted, that there is no explicit "C", the capacitance of the tuned circuit just being the stray capacitance.Blimey, that resonates with me . My old college lecturer taught us this bonkers ‘resonant frequency’ mnemonic: “Down in the jungle having a look see,..1 over 2pi root LC”
https://www.hamradio.co.uk/aerials-...super-antenna/mc2-2m-coil-for-mp1-pd-7187.phpThanks John, I was looking unsucessfully for an image to explain the answer,
The good old days.......
You’ve have to at least give me some credit for remembering that formula from my youth,...almost 2 centuries later ;...or perhaps it just feels that long ago.In context, the problem with that mnemonic is that, in relation to the first pic I posted, that there is no explicit "C", the capacitance of the tuned circuit just being the stray capacitance.
In the second pic I've just posted, there is an explicit "C" (in addition to the stray capacitance), but it's just an improvised one (just two copper disks, one of which can be moved relative to the other) - so, without some calculations (which are unlikley to be very accurate!), one doesn't know the value of its capacitance!
Kind Regards, John
I recently asked exactly the same myself. I know that my eyesight is not what it was decades ago, but that's certainly not the entire answer.What is it with resistors these days, do they print the band's on them in less definable colours, or is it just my eyesight, really struggle with them now
Oh, sure, you get full credit.You’ve have to at least give me some credit for remembering that formula from my youth,...almost 2 centuries later ;...or perhaps it just feels that long ago.
I recently asked exactly the same myself. I know that my eyesight is not what it was decades ago, but that's certainly not the entire answer.
The resistors are, of course, generally a lot smaller than they used to be - which (from the point-of-view of 'reading' them) is not a good start. However, I think it's the actual colours they now use which is the main problem these days - coupled with the background colour. The ones (which are very common) that drive me most mad are those with dark blue backgrounds. With those, I often find it difficult (or impossible) to work out what colours the bands are meant to be.
As I recently wrote, with resistors like that, these days I very often find myself reaching for my meter 'to check' (or even 'find out' in some cases!) the resistance - something I would never have had to do a few decades ago.
Given that a high proportion of commercial/industrial assembly of electronic things is now done by 'robots', I wonder if the problem is that they are now prioritising 'machine readability', rather than 'human readability'?
Kind Regards, John
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