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K1 RF Board - Resistance Checks

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Joseph M. Durnal

K1 RF Board - Resistance Checks

I'm working on the RF board and I've reached the first chance to do
resistance checks in the manual and I have some questions and one
major concern.

There are a few checks that when I first touch the meter to it will
flash a few ohms and within a second go to the desired value.

For example (from PG 29):
With the meters negitave lead on the ground near J7,
P1 pin 8 reads about 150 ohms (it varies slightly from test to test)
for less than a second then goes over 100k ohms

U3 pin 3 shows 46 with the VOM set to 200K. I really don't know what
that means, I'm thinking that is 46,000 ohms, which is less than 200k
U3 pin 5 is shows 20 with the VOM set to 20K, again, I'm assuming that
is 20k, which is greater than 10k

Now for my major concern,
U4 pin 4 reads only 0.4 ohms - I think I have a problem here, but I
have no idea what it could be, the manual said it should be > 50k.
The schematic seems to show it as a ground.

I'm glad I started with a K1 - I don't think I was really ready for
it. I can't even figure out how to read my VOM (although I'm going to
go practice on some known value resistors while waiting for replies to
this e-mail). Still, when I get this radio to work, I'm sure going to
enjoy making QSOs. Then comes the K3 but I also hope to build a K2
down the road as well.

Thanks & 73 de Joseph Durnal NE3R
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crstrode

RE: K1 RF Board - Resistance Checks

U4 pin 4 reads only 0.4 ohms - I think I have a problem here, but I have no idea what it could be, the manual said it should be > 50k.
The schematic seems to show it as a ground.

You should be checking U4 Pin 3
Pin 4 is indeed ground.

Carl Strode
WA7CS
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Joseph M. Durnal

Re: K1 RF Board - Resistance Checks

Well that is a big help! Thanks. At least this time I know how to
count the pins on an IC, when I built the Filter board, I didn't but
assumed I did and was very confused.

Pin 3 starts at about 20k for a second or less then jumps to well over 50k.

Thanks & 73 de Joseph Durnal NE3R

On Jan 30, 2008 2:09 PM, Strode, Carl R <[hidden email]> wrote:

>
>
> U4 pin 4 reads only 0.4 ohms - I think I have a problem here, but I have no idea what it could be, the manual said it should be > 50k.
> The schematic seems to show it as a ground.
>
> You should be checking U4 Pin 3
> Pin 4 is indeed ground.
>
>
> Carl Strode
> WA7CS
>

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Joseph M. Durnal

Re: K1 RF Board - Resistance Checks

It is a DMM - sorry. $3 hamfest special, no brand, but it says model
DM-301 on it!

Thanks - you've sort of answered my question about the waiting about a
second to get a reading too.

73 de Joseph Durnal NE3R

On Jan 30, 2008 2:44 PM, Don Wilhelm <[hidden email]> wrote:

> Joseph,
>
> You said you were using a VOM to measure resistance, and that may be your
> problem. Many VOMs use a battery voltage when measuring resistance that is
> high enough to turn on solid state devices and can even destroy them.
>
> Use a DMM for better results. Even the $5 to $10 ones perpetually 'on sale'
> at Harbor Freight Tools will give good results - cheap DMMs are accurate,
> they do take more time for the readings to settle down than the expensive
> ones, but if you wait about a second, they will tell you the correct story.
>
> 73,
> Don W3FPR
>
> Joseph M. Durnal wrote:
>
> Well that is a big help! Thanks. At least this time I know how to
> count the
> pins on an IC, when I built the Filter board, I didn't but
> assumed I did and
> was very confused.
>
> Pin 3 starts at about 20k for a second or less then
> jumps to well over 50k.
>
>
> Thanks & 73 de Joseph Durnal NE3R
>
> On Jan 30, 2008
> 2:09 PM, Strode, Carl R <[hidden email]> wrote:
>
>
>
> U4 pin 4 reads only 0.4 ohms - I think I have a problem here, but I have no
> idea what it could be, the manual said it should be > 50k.
> The schematic
> seems to show it as a ground.
>
> You should be checking U4 Pin 3
> Pin 4 is
> indeed ground.
>
>
> Carl Strode
> WA7CS
>
>
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> http://www.elecraft.com
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>