K2 low power

classic Classic list List threaded Threaded
4 messages Options
Reply | Threaded
Open this post in threaded view
|

K2 low power

Conway Yee
I have found low power on initial transmitter tests of my K2 construction.
I am unable to get above about 1 Watt before I get High Current.

I can not find any obvious error in winding T1-4. I reflowed all the
joints involved in the toroids.

Q6 is warm.  I am unable to assess the temperature of Q7 or Q8 because of
the heatsink.

No errors noted in the resistors in measuring power output.

tnx.
Conway Yee, N2JWQ

______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K2 low power

Don Wilhelm-4
Conway,

Does the same thing occur on all bands?  If so, re-check the turns on T4
and be certain it is not mounted backwards - the 'links' go only from
the front of the core to the back (each one goes through only one hole).
If the low power and high current are only on 160, 80, 40, 20, 15, and
10 meters, then check the number of turns on the Low Pass Filter
toroids.  Count the number of times the wire passes through the center
of the core.  On a toroid, a straight wire through the center is one
turn, a complete wrap around the core id two turns.

There are a few other possibilities, but they are less frequent and more
obscure than the ones I have mentioned.

If you feel Q6 is too warm, increase the value of R46 to 330 ohms (you
could do that arbitrarily and it will cause no problem).

73,
Don W3FPR

Conway Yee wrote:

> I have found low power on initial transmitter tests of my K2 construction.
> I am unable to get above about 1 Watt before I get High Current.
>
> I can not find any obvious error in winding T1-4. I reflowed all the
> joints involved in the toroids.
>
> Q6 is warm.  I am unable to assess the temperature of Q7 or Q8 because of
> the heatsink.
>
> No errors noted in the resistors in measuring power output.
>
> tnx.
> Conway Yee, N2JWQ
>  
>
______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K2 low power

Conway Yee
> If the low power and high current are only on 160, 80, 40, 20, 15, and
> 10 meters, then check the number of turns on the Low Pass Filter
> toroids.

It appears to be 80,40,10,12 only.  15 and 20 are OK.  I am in the middle
of checking the turns.

tnx.
Conway Yee, N2JWQ

______________________________________________________________
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
Reply | Threaded
Open this post in threaded view
|

Re: K2 low power

Don Wilhelm-4
Let me know if the LPF turns are the problem.  If not, I will have to
ask you to use an RF Probe (or preferrably an oscilloscope) to make some
comparative Signal Tracing reading between a band that works and one
that does not.

73,
Don W3FPR

Conway Yee wrote:

>> If the low power and high current are only on 160, 80, 40, 20, 15, and
>> 10 meters, then check the number of turns on the Low Pass Filter
>> toroids.
>>    
>
> It appears to be 80,40,10,12 only.  15 and 20 are OK.  I am in the middle
> of checking the turns.
>
>  
>
______________________________________________________________
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