Help: K2/100 # 2469

[Dan Holloway]

Hello all,

While checking my K2/100 before heading off on an IOTA trip (to OC-206
in August), to my amazement, I discovered that the receiver was dead.  I
have tried to resolve the problem but so far have failed to fix it.

I appeal to the very knowledgeable folks here for assistance.

Symptoms:  Transmit is normal, with the KPA100 and without (QRP);
sidetone, spot and keying are normal.
Receive: Only a hiss is audible.  I can very faintly hear the XG1 on
7040 kHz (RF and AF gain full).  With an antenna connected, I can very
faintly hear WWVH's tones on 10 MHz.  I first suspected the switching
diodes D2, D3 and D4 on the RF board but their voltages are normal as is
the 8V output of U4 on the RF board.  I recently built and installed the
KNB2.  I have only removed and reinstalled it.  I have not removed it
and reinstalled W5.  The NB display is as expected.  Turning it on/off
has no noticeable effect on the receiver.  This rig also has the K160RX
installed and I have removed and reinstalled it.  I have gone through
the Primary and Secondary menu options and have discovered nothing that
affects the receiver.

Prior to installing the KNB2, all was well; in fact, the rig managed to
work QRPDXCC so the rx was good then.

I suspect that this is a very simple fix.  Can someone help me?  I won't
be surprised if I am the problem and just can't see the forest for the
trees!

Thanks in advance and 72/73,

Dan
VK8AN
K2/100 # 2469

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[Don Wilhelm-3]

Dan,

As an easy quick check, put the antenna on the Receive Ant jack and see if
the receiver perks up - if it does, then you have Rant set on in the menu.

Since you said it worked before installing the KNB2, check there first.
Remove the KNB2 and jumper between pins 1 and 5 of J12 (the knb2 header).
If that does not bring the receiver back, check the R88, R89, and R90
locations.  The R89 position should have a jumper wire and either the R88 or
R90 should have a 2.7k resistor.

After you have done that, if you still do not hear normal receive, the
problem is somewhere other than the KNB2.  Try doing the Receiver Signal
Tracing steps detailed in the Troubleshooting appendix of the K2 manual.

73,
Don W3FPR



> -----Original Message-----

> Hello all,
>
> While checking my K2/100 before heading off on an IOTA trip (to OC-206
> in August), to my amazement, I discovered that the receiver was dead.  I
> have tried to resolve the problem but so far have failed to fix it.
>
> I appeal to the very knowledgeable folks here for assistance.
>
> Symptoms:  Transmit is normal, with the KPA100 and without (QRP);
> sidetone, spot and keying are normal.
> Receive: Only a hiss is audible.  I can very faintly hear the XG1 on
> 7040 kHz (RF and AF gain full).  With an antenna connected, I can very
> faintly hear WWVH's tones on 10 MHz.  I first suspected the switching
> diodes D2, D3 and D4 on the RF board but their voltages are normal as is
> the 8V output of U4 on the RF board.  I recently built and installed the
> KNB2.  I have only removed and reinstalled it.  I have not removed it
> and reinstalled W5.  The NB display is as expected.  Turning it on/off
> has no noticeable effect on the receiver.  This rig also has the K160RX
> installed and I have removed and reinstalled it.  I have gone through
> the Primary and Secondary menu options and have discovered nothing that
> affects the receiver.
>
> Prior to installing the KNB2, all was well; in fact, the rig managed to
> work QRPDXCC so the rx was good then.
>
> I suspect that this is a very simple fix.  Can someone help me?  I won't
> be surprised if I am the problem and just can't see the forest for the
> trees!
>
> Thanks in advance and 72/73,
>
> Dan
> VK8AN
> K2/100 # 2469

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