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KX3: Hi SWR on 20m & 30m after KX3-2M install

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Ed Hamlin

KX3: Hi SWR on 20m & 30m after KX3-2M install

Hi

I just recently installed the 2M transverter in my KX-3. I’m now noticing high (11 to 25) SWR readings on 20m and I wondered if this might be related (I don’t recall such high readings before). I’m using an off-center fed dipole that has worked quite well in the past. The KX3 autotuner worked so well in the past, and I’ve seen it tune on relatively short random wires, so inability to tune on a good antenna seems rather odd.

Part of the installation required displacing L40 and L43 on the main RF board to make room for the SMA connector. It’s possible to break one of the leads on the inductor while doing this. L40 (as I recall) felt pretty tight and I may have inadvertently pushed it too hard.

What would be the symptoms of an open circuit on either of those inductors? Other than high SWR on 20m and 30m, I haven’t seen any anomalous behavior.

73s
Ed
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ve3ibw

Re: KX3: Hi SWR on 20m & 30m after KX3-2M install

I had a similar situation with my KX3 just after the RTTY round-up at the
beginning of January. I also have the 2M module installed and experienced
the same challenges with the inductors. SWR values after 2M module install
seemed to be ok on HF. I actually can't recall if they were high as I
didn't check. But, the auto-tuner had no trouble achieving less than 1.5:1
matches with a regular ATU cycle (not the aggressive cycle) into my G5RV
shorty. After the round-up, I couldn't achieve less than 3 on most bands
(ATU assisted) and in some cases an SWR of 75:1!! I tried measurements
into two different dummy loads that I had around the shack. I bypassed the
ATU and measured on all bands. I had high SWR on all HF bands into both
dummy loads.

The sad ending to my tail is that I had to send the KX3 back to Elecraft
for warranty repair.

The report back, from the Elecraft tech looking at my rig, was that 5 of
the RF board's ICs were blown. Probable cause: near field lightning strike
or greater than 100+ watts of RF energy into the KX3. It is winter where I
am (snow, cold :-) and we don't get lightning at this time of year. Also,
I don't know how 100+ watts would have slipped into the KX3. It isn't near
any other RF source with that kind of power.

It is interesting, Ed, that you are reporting something similar to my
situation. I hope you resolve your problem without having to send your KX3
back.

P.S. I struck up a nice email conversation with the folks at Elecraft
support and they guided me through some tests and asked for measurements.
They too didn't want me to have to send the rig back. But, the results of
the SWR measurements told them that something bad was wrong and the KX3
needed servicing.

regards,
Brian
VE3IBW

On Wed, Jan 28, 2015 at 1:59 PM, Ed Hamlin <[hidden email]> wrote:

> Hi
>
> I just recently installed the 2M transverter in my KX-3. I’m now noticing
> high (11 to 25) SWR readings on 20m and I wondered if this might be related
> (I don’t recall such high readings before). I’m using an off-center fed
> dipole that has worked quite well in the past. The KX3 autotuner worked so
> well in the past, and I’ve seen it tune on relatively short random wires,
> so inability to tune on a good antenna seems rather odd.
>
> Part of the installation required displacing L40 and L43 on the main RF
> board to make room for the SMA connector. It’s possible to break one of the
> leads on the inductor while doing this. L40 (as I recall) felt pretty tight
> and I may have inadvertently pushed it too hard.
>
> What would be the symptoms of an open circuit on either of those
> inductors? Other than high SWR on 20m and 30m, I haven’t seen any anomalous
> behavior.
>
> 73s
> Ed
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Regards,
Brian
VE3IBW

Frank Krozel

Re: KX3: Hi SWR on 20m & 30m after KX3-2M install

Brian,

Can’t help wondering if ESD or similar build-up occurred with low humidity in the winter.

Frank KG9H

On Jan 28, 2015, at 3:26 PM, Brian Waterworth <[hidden email]> wrote:

> I had a similar situation with my KX3 just after the RTTY round-up at the
> beginning of January. I also have the 2M module installed and experienced
> the same challenges with the inductors. SWR values after 2M module install
> seemed to be ok on HF. I actually can't recall if they were high as I
> didn't check. But, the auto-tuner had no trouble achieving less than 1.5:1
> matches with a regular ATU cycle (not the aggressive cycle) into my G5RV
> shorty. After the round-up, I couldn't achieve less than 3 on most bands
> (ATU assisted) and in some cases an SWR of 75:1!! I tried measurements
> into two different dummy loads that I had around the shack. I bypassed the
> ATU and measured on all bands. I had high SWR on all HF bands into both
> dummy loads.
>
> The sad ending to my tail is that I had to send the KX3 back to Elecraft
> for warranty repair.
>
> The report back, from the Elecraft tech looking at my rig, was that 5 of
> the RF board's ICs were blown. Probable cause: near field lightning strike
> or greater than 100+ watts of RF energy into the KX3. It is winter where I
> am (snow, cold :-) and we don't get lightning at this time of year. Also,
> I don't know how 100+ watts would have slipped into the KX3. It isn't near
> any other RF source with that kind of power.
>
> It is interesting, Ed, that you are reporting something similar to my
> situation. I hope you resolve your problem without having to send your KX3
> back.
>
> P.S. I struck up a nice email conversation with the folks at Elecraft
> support and they guided me through some tests and asked for measurements.
> They too didn't want me to have to send the rig back. But, the results of
> the SWR measurements told them that something bad was wrong and the KX3
> needed servicing.
>
> regards,
> Brian
> VE3IBW
>
>
>
> On Wed, Jan 28, 2015 at 1:59 PM, Ed Hamlin <[hidden email]> wrote:
>
>> Hi
>>
>> I just recently installed the 2M transverter in my KX-3. I’m now noticing
>> high (11 to 25) SWR readings on 20m and I wondered if this might be related
>> (I don’t recall such high readings before). I’m using an off-center fed
>> dipole that has worked quite well in the past. The KX3 autotuner worked so
>> well in the past, and I’ve seen it tune on relatively short random wires,
>> so inability to tune on a good antenna seems rather odd.
>>
>> Part of the installation required displacing L40 and L43 on the main RF
>> board to make room for the SMA connector. It’s possible to break one of the
>> leads on the inductor while doing this. L40 (as I recall) felt pretty tight
>> and I may have inadvertently pushed it too hard.
>>
>> What would be the symptoms of an open circuit on either of those
>> inductors? Other than high SWR on 20m and 30m, I haven’t seen any anomalous
>> behavior.
>>
>> 73s
>> Ed
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Don Wilhelm-4

Re: KX3: Hi SWR on 20m & 30m after KX3-2M install

In reply to this post by ve3ibw

Folks,

Do not be complacent about static coming in from the antenna in the winter.
Even though there may be no lightning - wind, rain or snow can build up
a very large static charge.

I am not saying that was Brian's situation, but be aware that
possibility does exist.

Make certain there is a DC path across your feedlines to bleed off a
static charge. A non-inductive resistor with a value between 5k and 50k
will do the job. If you use an antenna switch, that is a good place to
add those resistors. If you have no other choice, mount the resistor in
a PL-259 body and put it on one side of a TEE adapter - the rig goes on
one other side and the last side goes to the antenna.

73,
Don W3FPR

On 1/28/2015 4:26 PM, Brian Waterworth wrote:
> It is winter where I
> am (snow, cold :-) and we don't get lightning at this time of year.

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