Lee,
Yes, I would change that capacitor - there is a chance that it will
increase the output of the DDS and solve your power output problem.
There is a difference in some KX1s due to care during construction,
component tolerances, and a host of other factors.
Make certain you counted the toroid turns correctly - a straight wire
through the core is one turn, a full wrap around the core is 2 turns.
Count the turns that go through the core center.
If all else fails, you can install the KX1 power mod. If you have a
good stock of 1/4 watt resistors you may not need to order the kit.
Change R11 to 4.7 ohms and R30 to 33 ohms.
If those steps do not solve the power output situation, send me an
off-list email and we can make comparison measurements with my KX1.
The KX1 audio is not 'earbusting', but is normally adequate. Yes, you
may want to try headphones or earbuds with a higher SPL rating.
The "Quick Reference" is the only place in the KX1 manual where SLO,
SHI, and CAL are mentioned - I guess someone overlooked updating that
portion of the manual since the VERY early days of the KX1. Look at the
listing of menu items on page 65 and you will see DDS, BFO, and SIG to
make those settings.
This has been true since firmware rev 1.01. 1.02 is the latest version.
73,
Don W3FPR
On 6/17/2015 10:58 AM, KG5VU wrote:
Hi,
I just finished building KX1 Serial Number 2879 which is the standard
20M/40M version. It's a great little rig but, I have a few issues, one
major and two minor:
A) On final testing I only had about 2.5W on 20M and 2.0W on 40M with power
supply at 13.8V. I tried to compress the winding on L2, as suggested, but
this only degraded the output slightly (2.2W on 20M and 1.8W on 40M).
Checked the components on the board against the schematic and everything
checked out OK. Any ideas on what else I should try? Any idea what RF
voltage levels I should see at each stage? (I have several decent
oscilloscopes for testing if need be.)
B) The receiver is sensitive (I can hear 0.1 microvolt RF signal on 20 & 40)
but the audio level (particularly for weak signals) is pretty low unless I
advance the AF Gain control to full clockwise. Is this normal? Do I just
need to experiment with different sets of ear-buds?
C) The firmware on my KX1 is version 1.02. The Menu on my unit is different
than the Manual. It does not include SLO, SHI or CAL. Instead there are
SIG, DDS and BFO. Are support documents for revised version available?
For background, I had no difficulty during assembly. The KX1 passed all
tests except the transmit power output.
I did make one mistake during assembly however. I mistakenly inserted a .1
microfarad capacitor at C30 instead of a .01 microfarad capacitor. Since
everything seemed to be working, so I have not corrected this issue. Think
this could be significant?
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