[Elecraft] Items you think you can depend on

[Don Wilhelm]

ch,

I believe you will find that Elecraft designs are conservative.
To use a 15 volt rated capacitor on a 15 volt rail would be foolish.
You will find those capacitors rated at 25 or 50 volts.

73,
Don W3FPR

On 9/4/2017 9:05 PM, Christopher Hoover wrote:
>>
>> I hope you are saying that the derating for the components was based on a
>> 15V max input.    If there are 15V rated parts on the input rail, that's
>> not good.
> 
> 
> I just took a glance at the K3S schematics to see if I could tell.  Result
> was inconclusive.
> 
> Notes:
> 
> 
> C3 (10 uF), C8 (10 uF) and C22 (470 uF) on the PA I/O board have no voltage
> ratings specified on the drawings.
> 
> C85 (10 uF) on the DSP power supply has no voltage rating on the drawing.
> 
> C52 is 1000 uF / 10V on a regulated 8V rail.   That wouldn't have gotten
> past the design reviews I have been subjected to.   Most of the other caps
> on the 8V rail(s) are rated for 25V.
> 
> All but the 10 uF parts are likely tants or electrolytics.  10 uF could be
> those or ceramic.
> 
> C102 (10u, 10V) is ceramic and may be unsufficiently derated.  (See the
> recent thread on the loss of LCD segments; known problem to Elecraft
> support.)
> 
> Very few of the low value caps (which are all are probably MLCCs) have a
> voltage specified on the drawings.
> 
> 
> I probably missed something as It  is hard to do schematic review with
> PDFs, but we're lucky to have those.  Thank you, Elecraft!
> 
> -ch
> 
> 
> 
> On Mon, Sep 4, 2017 at 5:12 PM, Christopher Hoover <ch at murgatroid.com>
> wrote:
> 
>> I can answer that one. It is in the equipment manuals. 15V max.
>>> Some components are rated at that level.
>>
>>
>> I hope you are saying that the derating for the components was based on a
>> 15V max input.    If there are 15V rated parts on the input rail, that's
>> not good.
>>
>> 73 de AI6KG
>>
>>
>>
>>
>> On Mon, Sep 4, 2017 at 4:49 PM, Jack Brindle <jackbrindle at me.com> wrote:
>>
>>> I can answer that one. It is in the equipment manuals. 15V max.
>>> Some components are rated at that level.
>>>
>>> You really don’t want to go too high or you lose a lot of power
>>> dissipated in linear voltage regulators inside the equipment.
>>> Of course too low and the transmitters can have issues. Things like the
>>> KRC2, W2 and other peripherals should be able to
>>> work pretty well las low as 8 or 9 volts, but they are most happy at the
>>> same level as the transceivers.
>>>
>>> - Jack, W6FB
>>>
>>>
>>>
>>>> On Sep 4, 2017, at 4:31 PM, Phil Kane <k2asp at kanafi.org> wrote:
>>>>
>>>> On 9/4/2017 3:29 PM, Jim Brown wrote:
>>>>
>>>>> For several decades, 120/240 VAC became the Standard for single-phase
>>>>> distribution in North America. Those of us who call call it "110" are
>>>>> showing our age. :)
>>>>
>>>> And how many sources refer to it as "115 V" or worse "117 V".
>>>>
>>>> That raises the (on topic)  question of what is the acceptable
>>>> excursion/tolerance  standard for equipment designed to run on "12 V DC"
>>>> in light of the LiFePO4 battery discussion here recently.
>>>>
>>>> 73 de K2ASP - Phil Kane
>>>> Elecraft K2/100   s/n 5402
>>>>
>>>>  From a Clearing in the Silicon Forest
>>>> Beaverton (Washington County) Oregon
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>>
>>
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