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K2 RF Board Resistance Checks

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Al Gold

K2 RF Board Resistance Checks

Hi All,

I have a partially built K2 circa serial number 5000 and have completed
Assembly Stage II of the RF Board. All of the resistance numbers are fine
with the exception of U6 Pin 8 which reads 42.5 ohms and should be greater
than 100 ohms. I have checked everything on the board visually for two
days and checked the resistances of the resistors to no avail. No shorts,
no cold solder joints, no unsoldered pins. I have seen in the archives
where many people have had this same problem, but I have not found one with
an actual solution to the problem. If there is anyone out there that has
fixed their resistance problem on U6 can you please let me know what your
solution was.

Thanks and 73's,

Allan KB1CLB
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Don Wilhelm-4

Re: K2 RF Board Resistance Checks

Al,

The first thing to try is reversing your meter leads. Often ohmmeters
use a higher voltage which can make some solid state devices conduct.

Is the Control Board plugged into the RF Board? If so, remove it and
remeasure.

Is U8 oriented correctly? How about Q18 and Q19?
Check the values of R15 (33 ohms) and R9 (100k ohms)

If it still is low, tell us what you found with those checks and ask again.

73,
Don W3FPR

On 2/20/2011 5:37 PM, Al Gold wrote:

> Hi All,
>
> I have a partially built K2 circa serial number 5000 and have completed
> Assembly Stage II of the RF Board. All of the resistance numbers are fine
> with the exception of U6 Pin 8 which reads 42.5 ohms and should be greater
> than 100 ohms. I have checked everything on the board visually for two
> days and checked the resistances of the resistors to no avail. No shorts,
> no cold solder joints, no unsoldered pins. I have seen in the archives
> where many people have had this same problem, but I have not found one with
> an actual solution to the problem. If there is anyone out there that has
> fixed their resistance problem on U6 can you please let me know what your
> solution was.
>

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AC7AC

Re: K2 RF Board Resistance Checks

In reply to this post by Al Gold

CONTENTS DELETED

The author has deleted this message.

David Christ

Re: K2 RF Board Resistance Checks

What is the maximum safe voltage? It must be less than 1.5 v as that
is what the Simpson and Triplett VOMs use in their lower ranges, but
how much less?

David K0LUM

At 3:47 PM -0800 2/20/11, Ron D'Eau Claire wrote:

>
>
>I trust you are using a DMM and not a VOM (like the old Simpsons, etc. -
>just about anything with a "wiggly needle" meter ;-) All of the older
>meters applied a dangerous amount of voltage to the circuit for today's
>solid state components
>
>Good luck!
>
>Ron AC7AC
>

AC7AC

Re: K2 RF Board Resistance Checks

CONTENTS DELETED

The author has deleted this message.

Don Wilhelm-4

Re: K2 RF Board Resistance Checks

In reply to this post by David Christ

David,

If the voltage is over 0.6 volts, and is applied to the base of a
transistor (assuming the emitter is grounded), the transistor will
conduct. So my answer it less than 0.6 volts. OTOH, if the voltage is
less than 0.3 volts, you will not be able to make diode forward
conduction tests with the ohmmeter (those meters will usually have a
diode test setting).

73,
Don W3FPR

On 2/21/2011 5:15 PM, David Christ wrote:

> What is the maximum safe voltage? It must be less than 1.5 v as that
> is what the Simpson and Triplett VOMs use in their lower ranges, but
> how much less?
>
> David K0LUM
>
> At 3:47 PM -0800 2/20/11, Ron D'Eau Claire wrote:
>>
>> I trust you are using a DMM and not a VOM (like the old Simpsons, etc. -
>> just about anything with a "wiggly needle" meter ;-) All of the older
>> meters applied a dangerous amount of voltage to the circuit for today's
>> solid state components
>>
>> Good luck!
>>
>> Ron AC7AC
>>
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> Elecraft mailing list
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>
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> Please help support this email list: http://www.qsl.net/donate.html
>