Stan Gibbs wrote
Don, I tried your experiment but it had no effect. I just grounded point A
because it is damn hard to jumper Q7. R28 measures good and is well
soldered. It has -0.25V or so on the base side and 5.5V on the other
during transmit.
I also tried reducing the drive pot and,
Ian,
IanMW wrote
Just to recap my earlier thoughts, I think your Q7 is fine, the negative
voltage is a red herring. It's due to the RF that is being grounded via Q7
(its task).
...
In the mean time, I'd get up a hill!
Thanks for taking the time to check out your rig for comparison.
Stan,
Another thing to check carefully is the 20 meter low pass filter
following the DDS - L4, L5, C50, C51 and C52. Check for good soldering
and proper values. Since L4 and L5 now being supplied do not fit the
holes, be certain the bent under leads are not touching another solder
pad or
Don,
I took a look at all those components, their values and installation, and
everything looks normal. It may be that one of those components is bad, or
that the DDS is exceeding its spec harmonic output for some reason.
I'm not certain that these harmonics are not somehow an artifact of my
Stan,
Looking at your KX1's 20m Tx spectrum shown in your picture, my impression
is that the wide pedestal in the bottom part could be due to phase noise. I
will return to this later. However as I do not own a P3, which I think you
are using, I am not familiar with how signals look on the P3
Here is a shot of my KX1's 40m signal:
http://elecraft.365791.n2.nabble.com/file/n7539479/KX1_40m.jpg
Clearly, the signal is much cleaner than 20m.
Here is another shot of the 20m signal at a 2 KHz span:
http://elecraft.365791.n2.nabble.com/file/n7539479/KX1_20m.jpg
Anybody have an idea for
Stan,
Check the low pass filter components carefully. It is possible that it
is letting harmonics through.
Make certain that Q7 is working. Capacitor CA is one of the low pass
filter components that must be in the circuit on transmit. Q7
effectively grounds one side of that capacitor on
Don Wilhelm-4 wrote
Make certain that Q7 is working. Capacitor CA is one of the low pass
filter components that must be in the circuit on transmit. Q7
effectively grounds one side of that capacitor on transmit.
As I said in my original post, Q7 is the place where my DC troubleshooting
Hello Stan,
If Q7 is not conducting and is not in effect grounding one side of CA, then
a loop is created between the input (Q1 Gate) and output stage of the
transmitter. Part of this loop contains the Rx RF Gain pot R1, the Rx's
input tuned circuit, and the coupling between pins 1 and 6 of
Actually, there is an easier test - just put a temporary jumper between
the connector and emitter of Q7. Do not expect it to receive with that
jumper in place, but observe what happens to the sidebands when you
transmit. If it cleans things up with the jumper in place, replace Q7
and make
But that requires the use of solder :-)
73,
Geoff
LX2AO
On May 09, 2012 at 02:02 +0200, Don Wilhelm wrote:
Actually, there is an easier test - just put a temporary jumper between
the connector and emitter of Q7. Do not expect it to receive with that
jumper in place, but observe what
Sooo??? - the KX1 is a solder type kit. It is the KX3 that is no
solder.:-)
I meant to say collector instead of connector - please forgive -
actually my excuse is that the letters are wearing off my keyboard and I
am not fully a touch typist - only halfway there, so you pardon the
mistypes.
Don, I tried your experiment but it had no effect. I just grounded point A
because it is damn hard to jumper Q7. R28 measures good and is well
soldered. It has -0.25V or so on the base side and 5.5V on the other during
transmit.
I also tried reducing the drive pot and, while the signal
The 20m waveform on my P3 seems very broad, but I don't think that it is due
to any kind of oscillation. The signal is 20 KHz wide at about 40 dB down.
I don't know if this is normal or not, but I did manage to make 20m and 40m
QSOs last evening with good signal reports for both.
I made the
Stan Gibbs wrote
The signal is 20 KHz wide at about 40 dB down.
I meant to say 2KHz wide, not 20...
Here is a picture for those who might be interested:
http://elecraft.365791.n2.nabble.com/file/n7537460/KX1_20m.jpg
-
73, Stan - KR7C
--
View this message in context:
Stan,
Do you have the proper number of turns on the LPF toroids. Count them
and count again. I suspect you may have one extra turn giving you the
lower power on 40 meters.
I am not sure why you get the wide signal on 20 meters, because an extra
turn on the toroids would reduce the cutoff
Hi Don,
All of the toroidal inductors and transformers have the correct number of
turns.
-
73, Stan - KR7C
--
View this message in context:
http://elecraft.365791.n2.nabble.com/New-KX1-low-power-and-20m-oscillation-tp7531133p7537532.html
Sent from the Elecraft mailing list archive at
Stan,
Thanks for checking.
Try spreading the turns out evenly over the full diameter of the core.
You should be able to achieve 3 watts or more on each band with a 13m8
volt power supply.
73,
Don W3FPR
On 5/7/2012 10:19 PM, Stan Gibbs wrote:
Hi Don,
All of the toroidal inductors and
Don Wilhelm-4 wrote
Try spreading the turns out evenly over the full diameter of the core.
Which core are we talking about? The manual says to squeeze the windings
of L2 if the 40m power is lower than 20m. I tried that and it did seem to
raise the 40m power, though still not as high as 20.
Stan,
Without a 'scope or Spectrum Analyzer connected to your KX1, I don't
know haw to answer, but my best guess is that you have a 20 meter low
pass filter that has a cutoff frequency that is lower than normal
(spreading the LPF turns will help with that, while the LPF cutoff for
40 meters
I may have been a bit hasty in concluding that there were oscillations on
20m; after I disconnected my K3's 20m antenna, the 20m signal looks fine.
So I may have just been overloading the K3's front end. Not sure why the
40m signal didn't suffer the same issue, though.
Still have a very low
Stan,
I was not available yesterday, so could not respond to your initial post.
The problem is most likely in the Low Pass Filter, so count the turns on
L1 and L2 very carefully - count the number of times the wire passes
through the center of the core. Double check the capacitors in the LPF
Just finished building the KX1 and the transmit testing is not going well. My
only bench tool is a DVM.
Power supply is a 13V battery. Ant is a 50 ohm dummy load. The receiver
seems to work fine. All DC voltages on RX are nominal.
On 40m TX, I get about 1.5W out. The signal is clean
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