[K2] RF Board: R115 resistance check

[IZ2NYY]

Hy to all, just finished the resistance check of RF Board (K2 #6995) as on page
62 of the manual. I've dne the check with two gears, an HP3478a and an Extech
470 (handheld dmm). I have different values as indicated down here:

HP
R115 160 ohms (ref.is >500ohms)
U6 PIN 8  290ohms (ref is >100 ohms)
U4 PIN 16 3,4 K (ref is >1k)
U11 PIN 8 0,7 K (ref is >250 ohms)
U10 PIN 8 5,19 K (ref is >500 ohms)
U12 PIN 1 0,58K (ref is >500 ohms)

EXTECH
R115 3,7K ohms (ref.is >500ohms)
U6 PIN 8  290ohms (ref is >100 ohms)
U4 PIN 16 3,4 K (ref is >1k)
U11 PIN 8 1,1 K (ref is >250 ohms)
U10 PIN 8 230 K (ref is >500 ohms)
U12 PIN 1 2,43 K (ref is >500 ohms)

You all can note the differences between the two instruments, the values are by
the way between the references given by the manual except the R115 value that on
the HP is only 160 ohms. I would like to assume that the HP is a better
instruments than the poor handeld dmm from Extech (excellent by the way), but in
this case i have perhaps the problem of a bad value of resistance on R115. Is
there anyone who can makes any comment about these differences and about the bad
value of R115???
IZ2NYY
Giuseppe "Pippo" Sorrentino
Milano ITALY


     
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[Don Wilhelm-4]

  Pippo,

Try reversing the leads of the HP3478a and re-measure.  Diode D12 is
connected, and the polarity of the HP when measuring resistance may be
such that the diode conducts.

73,
Don W3FPR

On 1/19/2011 5:36 AM, Giuseppe Sorrentino wrote:

> Hy to all, just finished the resistance check of RF Board (K2 #6995) as on page
> 62 of the manual. I've dne the check with two gears, an HP3478a and an Extech
> 470 (handheld dmm). I have different values as indicated down here:
>
> HP
> R115 160 ohms (ref.is>500ohms)
> U6 PIN 8  290ohms (ref is>100 ohms)
> U4 PIN 16 3,4 K (ref is>1k)
> U11 PIN 8 0,7 K (ref is>250 ohms)
> U10 PIN 8 5,19 K (ref is>500 ohms)
> U12 PIN 1 0,58K (ref is>500 ohms)
>
> EXTECH
> R115 3,7K ohms (ref.is>500ohms)
> U6 PIN 8  290ohms (ref is>100 ohms)
> U4 PIN 16 3,4 K (ref is>1k)
> U11 PIN 8 1,1 K (ref is>250 ohms)
> U10 PIN 8 230 K (ref is>500 ohms)
> U12 PIN 1 2,43 K (ref is>500 ohms)
>

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