K2 RF board part C72 Identity

[Tim Logan]

I'm having trouble locating this part. Manual says it should be labeled
271. I have a small blue cap that is labeled 2.7C. Could this be C72?
Thanks for any help.
73/Tim NZ7C
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[John Lonigro]

Tim:

I am using my Rev E manual for reference.  It might be slightly
different in yours.  There is a 2.7 pf capacitor (C22) listed and I'm
wondering if you have identified that when you did your inventory.  I
suspect the blue 2.7C cap you found might be that one.  Also, there is a
27 pf capacitor (C198) which in my manual is erroneously described in
the parts list as "27" or "271", but I believe it should have said "27"
or "270".  The really confusing aspect of it all is a 270 pfd capacitor
should be labelled "271", so you have the case where something marked
"270" isn't a 270 pfd capacitor.  I found all of this while doing
inventory and made sure I marked them unambiguously so I wouldn't get
them mixed up when it was time to install them.

Good luck and 73's,

John AA0VE


Tim Logan wrote:

> I'm having trouble locating this part. Manual says it should be
> labeled 271. I have a small blue cap that is labeled 2.7C. Could this
> be C72? Thanks for any help.
> 73/Tim NZ7C
>
>
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[G3VVT]

 
In a message dated 23/01/05 12:19:41 GMT Standard Time,  
[hidden email] writes:

The  really confusing aspect of it all is a 270 pfd capacitor
should be  labelled "271", so you have the case where something marked
"270" isn't a  270 pfd capacitor.


---------------------------------------------------------------------
 
The problem with marking small capacitors is providing the value on them so  
that it is more easily readable. What the manufacturers of the bulk of the  
capacitors now used by Elecraft is that the last digit of the three  provided is
the multiplier. This is just the same as with resistor color  codes.
 
Following this a capacitor marked 271 is 27 with a multiplier of 10 = 270  pF
(27 x 10 = 270). For a 27pF capacitor this would be marked  270 = 27 with a
multiplier of 1. (27 x 1 = 27)
This can be useful when higher values of capacitor are used. For example  
0.1uF = 100nF = 100,000pF and would be marked 104. This is 10 with a  multiplier
of 10,000 (10 x 10000 = 100,000pF).
 
After a while reading the capacitor values becomes automatic just as one  
learns to read the resistor color code. Not really sure which way I read the  
values of resistors, but suspect I look at the last digit first to see the  
multiplier and then the value within that multiplier. Now do the same with the  
capacitors that Elecraft use.
 
The problem arises with this capacitor marking system with values below  10pF
cannot be accommodated and manufacturers either resort to just providing  the
value direct or adding a *p* where the decimal point should be. Philips use  
the *p* or the *n* for marking their capacitors. This means a 2.7pF  capacitor
would be marked 2p7 and a 0.1uF or 100nF capacitor would be marked  100n.To
be sure I check all the values of the capacitors in doubt with the  capacitance
measuring facility in my DVM. A large proportion of the DVM seem to  have
this facility provided even down to the low cost versions and at  least my $50
DVM will measure down to single digit pF values with reasonable  accuracy.
 
Bob, G3VVT
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[Don Wilhelm-3]

John, Tim and all,

Usual capacitor markings are not really hard to interpret - they are just
like resitor color codes but using numbers instead of colors.  They use 3
digits - 2 significant digits followed by a multiplier.  The multiplier
tells us how many zeros to add - so 470 would be a 47 pf capacitor, 471 is
470 pf, 472 is 4700 pf, etc.

The exception is that values in the range 0 to 9.9 pf are usually marked
with their actual value (and usually followed by a letter) - and values from
10 pf to 99 pf can be marked with just their value (but it will have only 2
digits, not 3).  If the marking contains only one or two numbers, that
number is the capacitor value, and if it contains a decimal point, that
marking is most certainly the value.

Yes, there are several ways that capacitors can be marked, just look at the
component data section of an ARRL handbook to become familiar with the
variety, but for the most current production capacitors, the marking rules
indicated above will hold true.

73,
Don W3FPR

----- Original Message -----
From: "John R. Lonigro" <[hidden email]>
Cc: "Elec-Reflector" <[hidden email]>
Sent: Sunday, January 23, 2005 7:29 AM
Subject: Re: [Elecraft] K2 RF board part C72 Identity

> Tim:
>
> I am using my Rev E manual for reference.  It might be slightly different
> in yours.  There is a 2.7 pf capacitor (C22) listed and I'm wondering if
> you have identified that when you did your inventory.  I suspect the blue
> 2.7C cap you found might be that one.  Also, there is a 27 pf capacitor
> (C198) which in my manual is erroneously described in the parts list as
> "27" or "271", but I believe it should have said "27" or "270".  The
> really confusing aspect of it all is a 270 pfd capacitor should be
> labelled "271", so you have the case where something marked "270" isn't a
> 270 pfd capacitor.  I found all of this while doing inventory and made
> sure I marked them unambiguously so I wouldn't get them mixed up when it
> was time to install them.
>
> Good luck and 73's,
>
> John AA0VE
>
>
> Tim Logan wrote:
>
>> I'm having trouble locating this part. Manual says it should be labeled
>> 271. I have a small blue cap that is labeled 2.7C. Could this be C72?
>> Thanks for any help.
>> 73/Tim NZ7C
>>
>>
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>

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[Michael Pfeuffer]

Hi Tim,

I just finished the inventory on K2 #4693 yesterday.  The cap you have is
C22.  C72 is very similar, but is marked with a small triangle followed by
271J.

GL,
--Mike WQ5C

At 11:17 PM 1/22/2005, Tim Logan wrote:

>I'm having trouble locating this part. Manual says it should be labeled
>271. I have a small blue cap that is labeled 2.7C. Could this be C72?
>Thanks for any help.
>73/Tim NZ7C
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
>http://mailman.qth.net/mailman/listinfo/elecraft
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

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