Elecraft

K2: Low Output Only on 160M

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Michael Eberle

K2: Low Output Only on 160M

Hi,

I am having problems with my output power on 160M. It will only put out
about 1.5 watts when set for 10 watts. On all the other bands I am
getting between 9.4 and 10.3 watts.
I have double checked capacitors in the BPF section, double checked
capacitors and counted turns on toroid inductors on the low pass filter
board and found nothing obviously wrong.
relay K3 is switching properly and I really don't know what else to
check. It is my guess that someone on here will know exactly what I did
wrong or some other things to check.

Thanks,
Mike
KI0HA
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Don Wilhelm-4

Re: K2: Low Output Only on 160M

Mike,

The easiest way to troubleshoot that problem is to isolate the problem
to the failing stage.
Use the RF Probe and measure the points given for the transmit path
starting halfway down the left column on page 14
Making those measurements on 40 meters will not be meaningful for your
problem, but if you switch between 80 meters (or another working band)
and 160 meters, you can compare the amount of RF voltage at each stage.
Make the measurements in the order listed. The first point where the RF
voltage is significantly lower on 160 meters is a likely suspect.

Possible problem spots are:
1) The Transmit Buffer - are C94 and C150 the correct values and well
soldered?
2) The Bandpass Filter - are C13 and C14 the correct value (1200 pF
marked 122) and well soldered?

Check the VFO frequency at TP1 with the internal counter probe when
tuned to 1800 Hz. It should be near 6715 kHz. If it is not, check the
value and soldering of C75 (470 pF marked 471).

Low pass filter problems usually result in both low power out and high
current draw, but check the soldering of the K160RX toroids again. Make
certain the toroid leads are in the correct holes.

73,
Don W3FPR

On 5/11/2013 10:57 AM, Michael Eberle wrote:

> Hi,
>
> I am having problems with my output power on 160M. It will only put
> out about 1.5 watts when set for 10 watts. On all the other bands I
> am getting between 9.4 and 10.3 watts.
> I have double checked capacitors in the BPF section, double checked
> capacitors and counted turns on toroid inductors on the low pass
> filter board and found nothing obviously wrong.
> relay K3 is switching properly and I really don't know what else to
> check. It is my guess that someone on here will know exactly what I
> did wrong or some other things to check.
>
> Thanks,
> Mike
> KI0HA
> ______________________________________________________________
> 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
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Michael Eberle

Re: K2: Low Output Only on 160M

In reply to this post by Michael Eberle

Don, thanks for your reply. I do not understand your reference to page 14.
Page 14 in my manual is nothing but resistors being installed.

I have noticed that it is drawing 3.3 amps when set for 2 watts and displays Hi-Cur.

I have checked all the components you mentioned and everything appears to be correct.
Checking the TP1, I get 6714 khz.

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: [hidden email]
Cc: [hidden email]
Sent: Saturday, May 11, 2013 2:57:55 PM GMT -06:00 US/Canada Central
Subject: Re: [Elecraft] K2: Low Output Only on 160M

Mike,

The easiest way to troubleshoot that problem is to isolate the problem
to the failing stage.
Use the RF Probe and measure the points given for the transmit path
starting halfway down the left column on page 14
Making those measurements on 40 meters will not be meaningful for your
problem, but if you switch between 80 meters (or another working band)
and 160 meters, you can compare the amount of RF voltage at each stage.
Make the measurements in the order listed. The first point where the RF
voltage is significantly lower on 160 meters is a likely suspect.

Possible problem spots are:
1) The Transmit Buffer - are C94 and C150 the correct values and well
soldered?
2) The Bandpass Filter - are C13 and C14 the correct value (1200 pF
marked 122) and well soldered?

Check the VFO frequency at TP1 with the internal counter probe when
tuned to 1800 Hz. It should be near 6715 kHz. If it is not, check the
value and soldering of C75 (470 pF marked 471).

Low pass filter problems usually result in both low power out and high
current draw, but check the soldering of the K160RX toroids again. Make
certain the toroid leads are in the correct holes.

73,
Don W3FPR

On 5/11/2013 10:57 AM, Michael Eberle wrote:

Don Wilhelm-4

Re: K2: Low Output Only on 160M

Sorry, that page 14 is at the back of the manual in the Troubleshooting
Appendix.

73,
Don W3FPR

On 5/12/2013 5:50 AM, [hidden email] wrote:

> Don, thanks for your reply. I do not understand your reference to page 14.
> Page 14 in my manual is nothing but resistors being installed.
>
> I have noticed that it is drawing 3.3 amps when set for 2 watts and displays Hi-Cur.
>
> I have checked all the components you mentioned and everything appears to be correct.
> Checking the TP1, I get 6714 khz.
>
> ----- Original Message -----
> From: "Don Wilhelm" <[hidden email]>
> To: [hidden email]
> Cc: [hidden email]
> Sent: Saturday, May 11, 2013 2:57:55 PM GMT -06:00 US/Canada Central
> Subject: Re: [Elecraft] K2: Low Output Only on 160M
>
> Mike,
>
> The easiest way to troubleshoot that problem is to isolate the problem
> to the failing stage.
> Use the RF Probe and measure the points given for the transmit path
> starting halfway down the left column on page 14
> Making those measurements on 40 meters will not be meaningful for your
> problem, but if you switch between 80 meters (or another working band)
> and 160 meters, you can compare the amount of RF voltage at each stage.
> Make the measurements in the order listed. The first point where the RF
> voltage is significantly lower on 160 meters is a likely suspect.
>
> Possible problem spots are:
> 1) The Transmit Buffer - are C94 and C150 the correct values and well
> soldered?
> 2) The Bandpass Filter - are C13 and C14 the correct value (1200 pF
> marked 122) and well soldered?
>
> Check the VFO frequency at TP1 with the internal counter probe when
> tuned to 1800 Hz. It should be near 6715 kHz. If it is not, check the
> value and soldering of C75 (470 pF marked 471).
>
> Low pass filter problems usually result in both low power out and high
> current draw, but check the soldering of the K160RX toroids again. Make
> certain the toroid leads are in the correct holes.
>
> 73,
> Don W3FPR
>
> On 5/11/2013 10:57 AM, Michael Eberle wrote:
>> Hi,
>>
>> I am having problems with my output power on 160M. It will only put
>> out about 1.5 watts when set for 10 watts. On all the other bands I
>> am getting between 9.4 and 10.3 watts.
>> I have double checked capacitors in the BPF section, double checked
>> capacitors and counted turns on toroid inductors on the low pass
>> filter board and found nothing obviously wrong.
>> relay K3 is switching properly and I really don't know what else to
>> check. It is my guess that someone on here will know exactly what I
>> did wrong or some other things to check.
>>
>> Thanks,
>> Mike
>> KI0HA
>> ______________________________________________________________
>> 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
>>
> ______________________________________________________________
> 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
>