[Elecraft] [K2] Ooof.. Update

[Don Wilhelm]

  Larry,

You are trying to analyze too much in the KNB2 without looking at the 
schematic.  The signal always passes through the Bandpass Filter.  It 
only goes to the amplifier to detect noise.
So check the toroids L1 and L2, C3, C4, C6, C7, R8 and R8.
The RX signal should pass through the KNB2 with only those components in 
place and working.
Also check the soldering of P1 and its mating header on the K2 RF Board 
= make certain pin 1 has been soldered on both.

73,
Don W3FPR

On 3/21/2011 1:21 AM, L Kendall wrote:
> I'm having a similar problem after installing the KNB2.
>
> So, I triple checked component location and applicable polarity and all
> solder joints for bad joints or bridged/shorted solder pads; removed,
> checked and re-installed the 2 bandpass toroid chokes, checked the ID
> number on the caps.
>
> Checked the K2 RF board J12, and checked the mods to R88, R89&  R90.
>
> ...and the K2 is still nearly deaf as a post.
>
> Next, I jumpered 1&  6 on J12 and could then hear stations all over 40
> meters.
>
> Checked WWV @ 10 MHz and I thought it was going to blow the speaker
> before I could turn down the AF gain.
>
> So it looks like I did not screw up the K2 itself. That is a relief.
>
> I'm guessing the next thing to do is check U2 for correct voltage
> output, and if that's OK see what I can measure on the RF amp. It's an
> SMD and mounted on one of those SMD piggy back things for PCBs made for
> the old school DIP ICs.
>
> Kinda frustrating, but it happens.
>
> Larry
> K5END
>
>
>
>
>
>
>
>
>
> On Tue, 2011-01-18 at 22:43 -0500, Don Wilhelm wrote:
>
>
>> Try jumpering  (with a piece of bent wire) between pins 1 and 6 of the
>> J12 header.  If receive comes back to life, you have a problem on the
>> KNB2 board.
>>
>> Let us know the results.
>>
>> 73,
>> Don W3FPR
>>
>>
>> On 1/18/2011 10:26 PM, Brian Denley wrote:
>>> I am beginning to think I may have wacked or damaged the PIN diode for the
>>> T/R switch while adding the resistor for the KNB2.  That might explain no
>>> receive or transmit  that I am getting now.  Does that make sense?
>>> Brian
>>> KB1VBF
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