Yes, when HiCur is detected, the power will be reduced to the level
permitted by the value in the CAL CUR setting = and that value will be
stable.
If HiCur happens on 40 meters (but not 60 meters), and 20 meters (but
not 30 meters), 15 meters (but not 17 meters), and 10 meters (but not on
12 meters), check for an extra turn on the Low Pass Filter toroids.
73,
Don W3FPR
On 10/6/2014 1:44 AM, KY7K wrote:
Don,
Thank you for your recommendations.
D9 is a 1N5711 and checks OK.
A full reset made no difference.
Setting CAL CUR to 3.5 reduces the frequency of the HI-CUR messages, however
with the power control maxed it will still show up sometimes. Note that when
the HI-CUR occurs it is only for a second, after which the power drops down to
some random stable level.
Base of Q7 and Q8 are between .60 and .64 volts
While adjusting the power control with the radio in receive the power shown on
the display changes very smoothly as it should. However, if the power control
is adjusted while transmitting the power shown on the LCD display and the LED
bar graph jumps all over the place. The bar graph does show that the power is
increasing and decreasing overall as it should, what I mean by that is the bar
graph shows 4-5 bars of “noise” while adjusting the power in transmit, but the
overall direction of the “noise” goes up or down in the correct direction if
you were to average the “noise”.
Another test I made, however I’m not sure it is valid, was to control VPWR
manually by lifting R22 where is meets C45 and inserting a control voltage on
the lifted end of R22. In this mode the power is stable and varies smoothly as
the external control voltage is varied.
The power output is also stable from tune cycle to tune cycle in this test.
I question the validity of this test because VPWR and VALC are already setup
and stable prior to transmitting, unlike they normally would.
Steve - KY7K
k...@arrl.net
Get OUT and play radio!
On Oct 5, 2014, at 6:35 AM, Don Wilhelm <w3...@embarqmail.com> wrote:
Steve,
If "hooked up backwards" means that the DC power was connected with
reverse polarity, that will normally cause no harm to the K2 because
there is a series reverse voltage protection diode in the input power
line. The burned trace on the mic jack pin 5 suggests that something
different happened to it.
Try replacing D9 with a 1N5711 diode and see what happens. The power
output into a good dummy load will normally be within 0.2 watts of the
set power if all is working right. You older K2 has a 1N34 diode at D9
and it is not as accurate over the full frequency range as the 1N5711.
If you have not done so already, record the menu settings, especially
the filter settings and do a Master Reset (hold the 4, 5, and 6 buttons
in while powering the K2 on). Then run CAL PLL and restore the menu
settings. The fact that the problem goes away if you swap control
boards suggests that there may be some problem with the EEPROM contents,
and a Master Reset should 'clean it out'.
Set CAL CUR to 3.50 instead of 2.50 and see if the HiCur messages go
away. If they continue, you may have to replace the PA transistors.
Another thing to check is the DC voltage at the base of Q7 and Q8 during
a TUNE - it should be in the range of 0.60 to 0.64 volts. If not,
replace Q11 and Q13.
73,
Don W3FPR
On 10/5/2014 1:36 AM, KY7K wrote:
I forgot to mention that all testing is into a known good DL1 dummy load that
I’m also using for my external power readings.
Any wise insights are most welcome!
Steve - KY7K
k...@arrl.net
Get OUT and play radio!
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