Elecraft

Elecraft K2/10 Build and a lesson learned.

Classic

List

Threaded

4 messages Options

Cameron Francey

Elecraft K2/10 Build and a lesson learned.

Hi All,

I Just finished my Elecraft K2/10 build. I have lots of options to add but the basic K2/10 is now working and I'll let it settle in for a week or so to make sure its all ok before adding any options.

I started this build at the end of January, taking care to sort and identify all the parts, especially the fixed value capacitors so it made life much easier to select the correct values efficiently during the build.

Everything went well, got the phase 1 and 2 tests done, added the remainder of the components to finish phase 3 and then when I got to the transmitter alignment step I noticed that rather than about 2 watts out as expected it was over 20 watts! Gee, what was wrong I thought to myself? I had a quick look over everything, made 100% sure all the components were installed correctly etc, but couldn't find anything wrong. I even re-counted all the transformer winding's and made sure they were all installed correctly. Nothing looked out of place.

Having recently built two K1's and a K2/100 with KAT100 and nearly every option available I knew it had to be something I had done wrong. So I kept my logic head on and decided after my initial disappointment and re-checking my work that a break away from the bench was a good start.

Back to the bench this morning with a fresh mind I suspected that my issue was somehow with the components that either set or control the power level, and my reason for thinking that was because the issue was present on every band and the power control pot made no difference to the output power, and RX wise it was performing really well so that eliminated a lot of the sections. Thinking about ALC or the power control circuit on the control board I decided that was where to start and work outwards from there. I knew the transmit section of the main RF board was in good shape since it was capable of producing more than 20 watts into a dummy load!

So, I read the circuit diagram, pulled out the control board and started to trace the ALC circuit though the board.. That's when I found my problem, I couldn't believe how stupid I had been and missed soldering pin 2 of RP 3 on the Control Board, which is the ALC feedback loop. After soldering that and re-testing all was well, phew!!!

Where the lesson was learned was even though I'm close to obsessive compulsive when identifying and selecting each component and double checking twice before soldering anything, then checking with a magnifying glass that the joints look good I still somehow managed to let that un-soldered pin go unnoticed!

I don't think I have caused any adverse effects to the PA section driving it so hard. The short periods of transmitting at about 23 watts never caused them to heat up. Its interesting that the PA produced over 20 watts, so the 15 watts max output under normal conditions seems quite a conservative level for those 2SC1969's.

Just thought I'd share my stupid mistake with the readers here and that even being really careful things can still slip through the net!

Best Regards,

Cameron, AF7DK/GM7LQR

______________________________________________________________
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

Re: Elecraft K2/10 Build and a lesson learned.

Yes, you did good. One thing I learned when a friend had a project go south and could not find the reason. He brought it to me and it was an enameled wire that he had not striped the enamel off. The connection looked good but it did not burn through the enamel. Again DETAIL and double checks. Now where did I put my keys,,,,,,,
Mel, K6KBE

From: Ron D'Eau Claire <[hidden email]>
To: 'Cameron Francey' <[hidden email]>; [hidden email]
Sent: Saturday, February 25, 2017 3:41 PM
Subject: Re: [Elecraft] Elecraft K2/10 Build and a lesson learned.

Glad it turned out well in the end, Cameron. All "solder jockeys" know how a
joint sometimes magically "desolders" itself.

You were lucky after all. Often the unsoldered joint is making contact with
the thru-plated hole and everything works - until a little oxide builds up
and the resistance climbs until the circuit is open - often months or even
years later. Of course by then a component failure is the prime suspect and
many hours can be lost looking everywhere but the solder joints.

Enjoy your new K2. I built mine in 2000 and it is still a FB rig.

73, Ron AC7AC

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of
Cameron Francey
Sent: Saturday, February 25, 2017 3:03 PM
To: [hidden email]
Subject: [Elecraft] Elecraft K2/10 Build and a lesson learned.

Hi All,

I Just finished my Elecraft K2/10 build. I have lots of options to add but
the basic K2/10 is now working and I'll let it settle in for a week or so to
make sure its all ok before adding any options.

I started this build at the end of January, taking care to sort and identify
all the parts, especially the fixed value capacitors so it made life much
easier to select the correct values efficiently during the build.

Everything went well, got the phase 1 and 2 tests done, added the remainder
of the components to finish phase 3 and then when I got to the transmitter
alignment step I noticed that rather than about 2 watts out as expected it
was over 20 watts! Gee, what was wrong I thought to myself? I had a quick
look over everything, made 100% sure all the components were installed
correctly etc, but couldn't find anything wrong. I even re-counted all the
transformer winding's and made sure they were all installed correctly.
Nothing looked out of place.

Having recently built two K1's and a K2/100 with KAT100 and nearly every
option available I knew it had to be something I had done wrong. So I kept
my logic head on and decided after my initial disappointment and re-checking
my work that a break away from the bench was a good start.

Back to the bench this morning with a fresh mind I suspected that my issue
was somehow with the components that either set or control the power level,
and my reason for thinking that was because the issue was present on every
band and the power control pot made no difference to the output power, and
RX wise it was performing really well so that eliminated a lot of the
sections. Thinking about ALC or the power control circuit on the control
board I decided that was where to start and work outwards from there. I
knew the transmit section of the main RF board was in good shape since it
was capable of producing more than 20 watts into a dummy load!

So, I read the circuit diagram, pulled out the control board and started to
trace the ALC circuit though the board.. That's when I found my problem, I
couldn't believe how stupid I had been and missed soldering pin 2 of RP 3 on
the Control Board, which is the ALC feedback loop. After soldering that and
re-testing all was well, phew!!!

Where the lesson was learned was even though I'm close to obsessive
compulsive when identifying and selecting each component and double checking
twice before soldering anything, then checking with a magnifying glass that
the joints look good I still somehow managed to let that un-soldered pin go
unnoticed!

I don't think I have caused any adverse effects to the PA section driving it
so hard. The short periods of transmitting at about 23 watts never caused
them to heat up. Its interesting that the PA produced over 20 watts, so the
15 watts max output under normal conditions seems quite a conservative level
for those 2SC1969's.

Just thought I'd share my stupid mistake with the readers here and that even
being really careful things can still slip through the net!

Best Regards,

Cameron, AF7DK/GM7LQR

______________________________________________________________
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]

______________________________________________________________
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

Re: Elecraft K2/10 Build and a lesson learned.

In reply to this post by Cameron Francey

Cameron,

Don't feel bad, it happens to the best of us. I am glad you found the
problem.

Be careful to make certain pin 1 of the ICs and Rpaks is soldered. The
solder pad for pin 1 is a different shape than all the rest, and is
often missed by builders.

Congratulations on your troubleshooting skills. Good luck as you add
the options.

73,
Don W3FPR

On 2/25/2017 6:02 PM, Cameron Francey wrote:

> Hi All,
>
> I Just finished my Elecraft K2/10 build. I have lots of options to add but the basic K2/10 is now working and I'll let it settle in for a week or so to make sure its all ok before adding any options.
>
>
> I started this build at the end of January, taking care to sort and identify all the parts, especially the fixed value capacitors so it made life much easier to select the correct values efficiently during the build.
>
> Everything went well, got the phase 1 and 2 tests done, added the remainder of the components to finish phase 3 and then when I got to the transmitter alignment step I noticed that rather than about 2 watts out as expected it was over 20 watts! Gee, what was wrong I thought to myself? I had a quick look over everything, made 100% sure all the components were installed correctly etc, but couldn't find anything wrong. I even re-counted all the transformer winding's and made sure they were all installed correctly. Nothing looked out of place.
>
>
> Having recently built two K1's and a K2/100 with KAT100 and nearly every option available I knew it had to be something I had done wrong. So I kept my logic head on and decided after my initial disappointment and re-checking my work that a break away from the bench was a good start.
>
>
> Back to the bench this morning with a fresh mind I suspected that my issue was somehow with the components that either set or control the power level, and my reason for thinking that was because the issue was present on every band and the power control pot made no difference to the output power, and RX wise it was performing really well so that eliminated a lot of the sections. Thinking about ALC or the power control circuit on the control board I decided that was where to start and work outwards from there. I knew the transmit section of the main RF board was in good shape since it was capable of producing more than 20 watts into a dummy load!
>

______________________________________________________________
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]

Vic Rosenthal

Re: Elecraft K2/10 Build and a lesson learned.

In reply to this post by Cameron Francey

Many moons ago when there was a K2 but no KPA100 I wanted to drive an
amp with my K2 and I needed a few more watts. I made some modification
(I don't remember the details) that allowed it to produce more than 20
watts, which made a big difference in output from my amp. I operated for
a while like that until the KPA100 came out, and it didn't seem to hurt
anything.

73,
Vic, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/

On 26 Feb 2017 01:02, Cameron Francey wrote:

> Hi All,
>
> I Just finished my Elecraft K2/10 build. I have lots of options to
> add but the basic K2/10 is now working and I'll let it settle in for
> a week or so to make sure its all ok before adding any options.
>
>
> I started this build at the end of January, taking care to sort and
> identify all the parts, especially the fixed value capacitors so it
> made life much easier to select the correct values efficiently during
> the build.
>
> Everything went well, got the phase 1 and 2 tests done, added the
> remainder of the components to finish phase 3 and then when I got to
> the transmitter alignment step I noticed that rather than about 2
> watts out as expected it was over 20 watts! Gee, what was wrong I
> thought to myself? I had a quick look over everything, made 100%
> sure all the components were installed correctly etc, but couldn't
> find anything wrong. I even re-counted all the transformer winding's
> and made sure they were all installed correctly. Nothing looked out
> of place.
>
>
> Having recently built two K1's and a K2/100 with KAT100 and nearly
> every option available I knew it had to be something I had done
> wrong. So I kept my logic head on and decided after my initial
> disappointment and re-checking my work that a break away from the
> bench was a good start.
>
>
> Back to the bench this morning with a fresh mind I suspected that my
> issue was somehow with the components that either set or control the
> power level, and my reason for thinking that was because the issue
> was present on every band and the power control pot made no
> difference to the output power, and RX wise it was performing really
> well so that eliminated a lot of the sections. Thinking about ALC or
> the power control circuit on the control board I decided that was
> where to start and work outwards from there. I knew the transmit
> section of the main RF board was in good shape since it was capable
> of producing more than 20 watts into a dummy load!
>
>
> So, I read the circuit diagram, pulled out the control board and
> started to trace the ALC circuit though the board.. That's when I
> found my problem, I couldn't believe how stupid I had been and missed
> soldering pin 2 of RP 3 on the Control Board, which is the ALC
> feedback loop. After soldering that and re-testing all was well,
> phew!!!
>
>
> Where the lesson was learned was even though I'm close to obsessive
> compulsive when identifying and selecting each component and double
> checking twice before soldering anything, then checking with a
> magnifying glass that the joints look good I still somehow managed to
> let that un-soldered pin go unnoticed!
>
>
> I don't think I have caused any adverse effects to the PA section
> driving it so hard. The short periods of transmitting at about 23
> watts never caused them to heat up. Its interesting that the PA
> produced over 20 watts, so the 15 watts max output under normal
> conditions seems quite a conservative level for those 2SC1969's.
>
>
> Just thought I'd share my stupid mistake with the readers here and
> that even being really careful things can still slip through the
> net!
>
>
>
> Best Regards,
>
> Cameron, AF7DK/GM7LQR