Kurtt,
The KX1 should receive just fine with Q7 removed. Any other receiver
troubles are a different problem.
73,
Don W3FPR
Kurt Pawlikowski wrote:
Don, Et Al,
Looks like the unit may have had a static discharge through the
antenna. Q7, part of the receiver mute circuit was blown. I'll order
one tomorrow and go from there. Once I removed this component, 20
meters seems to be up there where it should be. Nothing else seems to
be receiving correctly right now, but I'll attribute that to either
this (now missing) part or some issue I accidentally introduced while
troubleshooting. We'll see!
Regards,
kurtt
Kurt Pawlikowski, AKA WB9FMC
The Pinrod Corporation
[EMAIL PROTECTED]
(773) 284-9500
http://pinrod.com
Don Wilhelm wrote:
Kurt,
From all you have said, I would believe that the problem is in the
KXB3080 low pass filter.
While I agree that your continuity test indicates no apparent problem
with the toroid lead tinning, check all the connections to be certain
there is a bit of solder on both sides of the board - if not, view
that connection with suspicion.
Make certain there is no contact with the green wire from L2 to the
lower connection of the red wire. The green wire must wrap around to
the back side of the LPF board and can inadvertently contact the #4
termination of the wire for the red winding.
The best LPF testing is visual - look for any suspicious solder
connections. Yes, you will see a 17 MHz cutoff on the LPF if you
measure it without regard to disconnecting it from the rest of the
circuit and failing to properly terminate the filter (it is not 50
ohms at the PA transistor side, but I have not ever calculated the
proper termination).
Perhaps it is helpful if I tell you that the green winding is the
only active portion on 40, 30 and 20 meters. The red winding is used
for 80 meters and SWB band below about 6 MHz only.
Caution: The sensitivity of the KX1 is not as great on 20 meters as
it is on 30 or 40 meters. Bringing a finger (or antenna) close to T2
or many of the receiver tuned circuits after the LPF will normally
result in an increase in receiver total output, but that is actually
an increase in broadband noise - under careful measurement
conditions, the desired signal strength will not increase even though
the overall noise level does. Spectrogram will show that is true.
73,
Don W3FPR
Kurt Pawlikowski wrote:
Hi,
First, thanks for reading. Hopefully, it won't be boring for those
lucky K3 guys and gals...
CONFIGURATION
KX-1, 3080 upgrade. ATU currently removed and antenna jumper
installed for testing.Using XG-2 as a signal source. I have confirmed
the XG-2 seems to be working about as expected with another receiver
(about S-10 at 50uv and S-0 (but still in the speakers) at 1uv).
SYMPTOM
With normal operation, receive levels appear normal on 80 and 40 (I
can make contacts), but the XG2 is not peaking the KX-1's meter (I used
the XG-2 to calibrate the meter). 20 meters has always seemed deaf to
me. I don't remember how well the XG-2 was received on 20 when I
calibrated it. Here's the real "kicker": On 20 meters, with the XG-2
attached, I hear *no* volume difference between 50 and 1uv (which means
the KX-1's receiver is picking up the signal by proximity, not through
the antenna connection). If I touch the RX antenna connection almost
anywhere between the low-pass filter and the input of the Rx Mixer (U6,
pin 1), 20 meters comes way up (from nothing to receiving moderately
weak signals and noise). Touching the RX antenna line on 80 and 40
appears to have little or no affect. Output power on 20 meters does not
register full power, but I'm not sure if this is a calibration problem
as I don't have an accurate power meter. Also, when I couple a grid dip
meter into the RX, when tuned to 30 or 20 meters, I get a marked "dip"
just at about 17 MHz.
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