Hi all,
I have finally had a chance to help out with my friends K2. Using both the RF
signal generator and an AF generator, signals do get through on all bands but
is very weakly. Even with the signal generator on the IF frequency, the signal
is very weak, even at the input to the detector. We injected an AF signal at
the output of the detector and it is very robust ... great audio and volume.
What I have noticed ... The maximum strength on the S meter (still low) occurs
when the signal is zero beat, weather a signal is injected at the antenna or an
IF signal is injected at the input to the detector, the NE612. I am currently
suspecting a bad BFO output or an alignment somewhere. That is currently where
we stand. Any suggestions before we start again in the New Year? Thanks.
73, Mike WA5POK
On Friday, September 19, 2025 at 08:12:18 PM EDT, Mike Furrey via Elecraft
<[email protected]> wrote:
Don, Thanks for the note.
I am currently at my TX home and when I return to TN in DEC, I am taking my
test gear (have plenty) to help my friend that has the non-receiving K2. I have
a decent Leader signal generator here and I use a frequency counter to check
the frequency. I also just dug up enough parts to build a 10 mHz generator.
To get myself tuned up to working on the K2 I am going to go through mine here.
Been working on too many old boat anchors lately.
73, Mike WA5POK
On Friday, September 19, 2025 at 07:24:37 PM EDT, W3FPR
<[email protected]> wrote:
Mike,
If you do not yet have a proper signal generator, try this - connect a
dummy load to the working K2, and set the power below 12 watts. On the
dead receiver, attach a short wire (not coax) as an antenna about 1 foot
long), and place it close enough to the working K2's dummy load to
produce the proper voltage at the bad K2 input (do not move the wire
after that, and do not change the powering K2's power level). Then
proceed with the receiver signal tracing as indicated in the manual.
You can use the TUNE button to set the working K2 to transmit a signal)
You should remove the KPA100 completely (Physically and electrically)
from the non-working K2 and use the lower panel BNC as the antenna input.
Again, let me know the first stage where the output is decidedly below
normal - stop and tell me where that point is and we can troubleshoot
that stage to the component level. I do not need/want any information
beyond that first failing point because it is not relevant until that
stage is repaired.
73,
Don W3FPR
On 9/8/2025 12:26 AM, Mike Furrey wrote:
> Hi Mike and Don,
>
> Thanks for the replies. We took out the 160 meter board and bypassed
> it with clip leads.It has s/n 36XX (trying to remember as Jim took it
> with him) We also pulled the KPA100 amp and used the BNC antenna jack
> to connect to a dummy load to check power output ... around 10 to 12
> watts, then to an antenna to listen for signals. I will talk with Jim
> tomorrow and we will start developing a plan on the bench. Most of my
> all of my test gear is at my TX home and we are currently in TN. I
> have a scope here and a test probe and might have enough stuff to
> build the crystal oscillator here ... once again plenty of stuff ...
> not in TN. Hi.
>
> Now that I just finished in the TNQP we will start a methodical look
> at the front end.
>
> We will keep y'all posted
>
> Thanks es 73,
>
> Mike WA5POK
>
> On Sunday, September 7, 2025 at 04:33:37 PM EDT, W3FPR
> <[email protected]> wrote:
>
>
> Mike,
>
> What is the serial number of that K2? If below 100, it is a Field Test
> model and is slightly different that those above that SN.
>
> I would not recommending "shotgunning" the problem, there is a
> methodical way to go about it which will lead to the problem area
> without guesswork.
>
> The best way to troubleshoot a dead receive problem with the K2 is first
> to remove the KPA100 completely, and then test the base K2 from the
> lower panel BNC connector.
> See the Troubleshooting section of the K2 manual (Appendix E). Since you
> do not have a signal generator, you could build up the crystal
> oscillator shown on page 9 of the Appendix. If you do not have a
> 'scope, you can use the RF probe also shown on page 9. It does not have
> to be 'pretty' for this job, pushing the component leads though
> cardboard and soldering them together will work fine for the frequencies
> involved here.
>
> The troubleshooting steps begin on the right column of page 10 and
> continue thru the left column of page 12. With the proper input level,
> you are looking to find the first stage that that has lower than
> expected output.
> Once you locate that stage, let me know and I can help you with
> component by component checks to solve the problem. Dave Van Wallingan
> W8FGU can also assist since he is the current /major repair person for
> the K2 and other legacy gear that I used to repair.
>
> 73,
> Don W3FPR
>
>
> On 9/7/2025 1:07 PM, Mike Furrey via Elecraft wrote:
> > At a hamfest a week ago there were two k2s for sale from an estate.
> I bought one and a friend (not on here yet) bought the other. His
> receiver is dead. The transmitter has full output (110 watts) on all
> bands. The receiver ... AF gain works, side tone works, filters work,
> and RF gain works. This can be heard in the change of the pitch/volume
> of the noise emitted.
> > ATTN and Preamp do not work/function. We see no codes. We made a
> cursory disassembly and unseated and reseated all the boards. It has
> the 160 meter option in, and we bypassed it. Unfortunately I sold my
> old signal generator at the hamfest in anticipation of getting a more
> up-to-date unit. Hmmm mabe use my old Model 59 GDO as a generator. We
> are thinking relay ... haven't yet gone into it that far. One thing
> that puzzles me is the RF gain control (R4). Where is it in the
> circuit? I see it connected to J1. I see it coming off of P1 and that
> is it where it ends!!?? I see R5, R6, R7, etc but I can't find where
> R4 connects? I am thinking a relay somewhere in there? loose jumper or
> plug I have overlooked? Maybe someone can throw me a bone as to a hint
> as to where to look for the missing RF to the receiver.
> > Many Thanks, Mike WA5POK
> > ______________________________________________________________
> >
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