[Elecraft] K2: Low Output Only on 160M

[mteberle at mchsi.com]

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" <w3fpr at embarqmail.com>
To: mteberle at mchsi.com
Cc: elecraft at mailman.qth.net
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
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