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KX1 died. Where to start?

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Oscar, WB5GCX

KX1 died. Where to start?

I built my KX1 about a year ago (#2199). Everything tested out and worked fine. It's been on the shelf until about two weeks ago. I finally got going on cw this past few months (I love my K3), then this past few weeks made a few contacts with my KX1 (what a thrill that was!). It's a wonderful radio!

When I went to turn it on today, it appears to be dead. I can hear some white noise in the earphones, but no display, no keyer/transmit sidetone, no relay sounds, etc. Same with internal 6 AA and external 12v. Only option installed is KXAT1.

I suppose I need to take out the board and start doing some of the troubleshooting shown in Appendix E -- but thought I'd check to see if someone else has had this happen and had a suggested (quick and easy :) solution - or a recommendation on where to start on troubleshooting.

Don Wilhelm-4

Re: KX1 died. Where to start?

Oscar,

Remove the board from the KX1 top cover and check to see if the MCU chip
is firmly seated in its socket. The narrow portion of the leads should
be fully engaged with the socket. It takes a bit of pressure to seat
this IC. Use your thumbs on the top of the chip and your fingers under
the board - press firmly.

73,
Don W3FPR

On 11/12/2010 7:26 PM, Oscar, WB5GCX wrote:

> I built my KX1 about a year ago (#2199). Everything tested out and worked
> fine. It's been on the shelf until about two weeks ago. I finally got
> going on cw this past few months (I love my K3), then this past few weeks
> made a few contacts with my KX1 (what a thrill that was!). It's a wonderful
> radio!
>
> When I went to turn it on today, it appears to be dead. I can hear some
> white noise in the earphones, but no display, no keyer/transmit sidetone, no
> relay sounds, etc. Same with internal 6 AA and external 12v. Only option
> installed is KXAT1.
>
> I suppose I need to take out the board and start doing some of the
> troubleshooting shown in Appendix E -- but thought I'd check to see if
> someone else has had this happen and had a suggested (quick and easy :)
> solution - or a recommendation on where to start on troubleshooting.

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Oscar, WB5GCX

Re: KX1 died. Where to start?

Don,
Removed and re-seated the MCU. No change in operation. Also closely inspected for no/bad solder -- all looks good.

Kept thinking about if I could have done anything to cause this. I remembered I had both the KX1 and my K3 connected via 18" jumpers to a coax A/B switch to share my main HF antenna. Was doing some receiver comparisons between the two, and have used this configuration to easily use the KX1 indoors with the main antenna. Always before I have always disconnected the coax from the KX1 before transmitting with the K3 (as well as moving the A/B switch to the K3 position).

The last time I had the KX1 hooked up this way, I may not have removed the coax from the KX1 before using my K3 on 40m cw, and 80m SSB. I'm not sure I tried/used the KX1 after doing this.

Could strong RF from the K3 maybe have "fried" the KX1 MCU (or other component)? Perhaps the A/B switch isolation is not so good -- or stray RF, etc.?

Oscar, WB5GCX

Don Wilhelm-4

Re: KX1 died. Where to start?

Oscar,

If your coax switch was connected properly, no harm should have been
done to the KX1.

OK, now that the MCU chip has been verified as fully seated, you are in
for some in-depth troubleshooting.
The first thing that should be checked is the DDS frequency - but if you
do not have a frequency counter, that is difficult.
I assume you do have another HF receiver (the K3 if nothing else) - if
so, operate the KX1 into a dummy load and couple the other receiver near
the dummy load with a short antenna - you should hear the KX1 transmit
quite close to the frequency on the KX1 dial.

If the KX1 transmit frequency is close to the frequency the KX1 is tuned
to, that part is good, and we can rule out the KX1 MCU and DDS for transmit.

Next, try a "quick and dirty" check of the KX1 receiver - connect the
center conductor of your antenna (using a jumper wire) to U6 pin 1 - do
you hear signals as you tune? If not, you are in for some greater "in
depth" signal tracing (tell me what equipment you have available) - but
if you do, then the problem is in the Low Pass Filter of your KX1.

73,
Don W3FPR

On 11/13/2010 8:27 PM, Oscar, WB5GCX wrote:

> Don,
> Removed and re-seated the MCU. No change in operation. Also closely
> inspected for no/bad solder -- all looks good.
>
> Kept thinking about if I could have done anything to cause this. I
> remembered I had both the KX1 and my K3 connected via 18" jumpers to a coax
> A/B switch to share my main HF antenna. Was doing some receiver comparisons
> between the two, and have used this configuration to easily use the KX1
> indoors with the main antenna. Always before I have always disconnected the
> coax from the KX1 before transmitting with the K3 (as well as moving the A/B
> switch to the K3 position).
>
> The last time I had the KX1 hooked up this way, I may not have removed the
> coax from the KX1 before using my K3 on 40m cw, and 80m SSB. I'm not sure I
> tried/used the KX1 after doing this.
>
> Could strong RF from the K3 maybe have "fried" the KX1 MCU (or other
> component)? Perhaps the A/B switch isolation is not so good -- or stray RF,
> etc.?
>
> Oscar, WB5GCX

Oscar, WB5GCX

Re: KX1 died. Where to start?

Don,

You said "you should hear the KX1 transmit quite close to the frequency on the KX1 dial"

But the display is not working on the KX1, so I don't know what band or frequency it's on...

The only signs of life are: 1) some white noise through the earbuds when I turn on the KX1, and 2) the white LED will come on when I switch it on.

I have no test equipment other than a decent VOM, so if it's not something pretty obvious I might have to send to Elecraft...

thanks,

Oscar, WB5GCX