HISTORY:
Sustainability is the name of the game! Anything (that has been tested and still functioning properly) should be repurposed creating saving in wasted Ee and reducing the poisoning our environment when items are buried in the earth at the local tip needlessly.
Never heard of Ee? It is a concept that creates a measurement of ALL things (not just electronics) that humans have made and the energy used in obtaining the raw material, processing the materials right through to a finished product and even should include the shipping of the item to the distributors/retailers.
If you would like to know more about Ee values, please take a look HERE
Oldies but goodies!
This Silver Mica capacitor is BRAND NEW but OLD Stock
These Silver Mica capacitors are highly desired due to their high accuracy, temperature co-efficient, low capacitance variation with changing voltages, high Q resulting in very small power factors. Due to the highly accurate, stable small capacitance values, these were often used in RF circuits.
ITT (International Telephone And Telegraph Company) is an American company, founded in 1920 and eventually expanding into many different divisions, one of which was components - capacitors being one of these. They had manufacturing facilities throughout the world and these silver mica capacitors I am offering were UK manufactured. ITT worked closely with STC (Standard Telephone And Cable UK) and a lot of the databook information I have about these silver mica capacitors was extracted from an STC component databook from the 1970's. The silver mica capacitor section actually has ITT stamped at the bottom of each page!. STC & ITT did have a LARGE joint manufacturing facility at Paignton/Devon UK, which at it's peak employed over 5000 staff!
The silver mica capacitors I am offering were actually from my very early days in electronics, the days of radio communication experimentation in the late 1970's to early 1980's
It is VERY IMPORTANT to read my notes below regarding testing ... the manufacturer ID marks did not make a lot of sense (to begin with) but after a lot of research I think I have now nailed exactly what these capacitors are ....
Read on for details of my quest in identifying these capacitors
ITT (USA) - Silver Mica Capacitor
273 Series
The package does not indicate the type of capacitor but I seem to recall that originally some of these were on tape (my own taped product has long ago been used in projects) so I did a bit of hunting around online ....
I found someone who also has the same capacitors and still has them on the tape! Nice ... this confirms my memory of these being Silver Mica.
It is important to never trust what you read online about things like this, the photographs tell the story. I even saw a seller online stating these are polypropylene capacitors! Absolute rubbish!
From the STC component databook (1970's), these silver mica capacitors have Ruby mica plates with silver electrodes internally, terminal wires connected internally using high melting point solder
Moulded in thermosetting resin
Tolerance: 1%
400V DC
Nominal Value: 435pF ** Read below about this value determination
Termination: Axial wire leads (2x 34mm length)
Dimensions: 12.2mm Wide x 11.45mm Height x 3.1mm Thick
Weight: 1g
** It's all about the value!
The Black resin body has the following printed text
(TOP)
n453F
(SIDE 1)
400V -
8011
(SIDE 2) - Stamped into the resin
ITT
273
Nowhere is the tolerance stated in numerals and that topside part number is confusing! The component databook indicates these were 1% tolerance but the part number is tricky because my databook only references the STC part numbers used, not ITT (although ITT is acknowledged as the manufacturer of the product, at Devon)
The 8011 is the manufacturing batch code.
These silver mica capacitors were produced in a value range of 5pF steps e.g 400pF - 405pF - 410pF and so on ... So what on earth is this n453 all about? They are certainly NOT 453pF and I proved this by testing EVERY SINGLE CAPACITOR (Yes I know, unbelievable but I wanted to solve this mystery)
The test results below clearly prove these are indeed 1% tolerance (actually that is what the F stands for in the part number) AND the nominal capacitance is 435pF not 453pF - weird numbering system, to have three numbers and take the last number and place it in the middle of the value. I have not seen this before.
So I tested each and every "little beastie", all 187 of them, and these measurements have been made as a "guide only" to give a "picture" of the pF value spread
Here are the results:
478pF
1 piece
476pF
1 piece
475pF
2 pieces
474pF
1 piece
473pF
1 piece
471pF
1 piece
440pF
5 pieces
439pF
11 pieces
438pF
16 pieces
437pF
32 pieces
436pF
THIS VALUE IS NOW SOLD OUT (26 pieces)
435pF
THIS VALUE IS NOW SOLD OUT (31 pieces)
434pF
THIS VALUE IS NOW SOLD OUT (4 pieces)
433pF
THIS VALUE IS NOW SOLD OUT (16 pieces)
410pF
1 piece
These results clearly show the bulk (around 80%) of the 435pF capacitors are measuring within 0.5% of the nominated value. A very "bell like" curve of values with 435pF being nominated value and you can see there has been a VERY SLIGHT shift upwards in value from 435pF but MOST still remaining well and truly within the 1% tolerance.
After this little exercise I now have these little packets, each marked with the specific value, of silver mica capacitors in the quantities indicated above. Although this advertisement for the value of 435pF, if you wish to have a more precise value from the tested capacitors then please let me know which specific value you would like in the range 478pF ~ 410pF
COSMETIC CONDITION:
BRAND NEW
OLD Stock (around 50 years old!)
CLEAN
The tinned leads remain readily solderable although the "shine" is now a dull silver colour but no serious oxidisation!
Now stored in sealed, labelled, clear plastic packets of each value in the range 410 ~ 478pF
*** Where the photograph shows multiple components, this advertisement is for ONE capacitor only - not all that are shown! Seems obvious but some people actually ask me this!
